Using magneto transport, we probe hopping length scales in the variable range hopping conduction of carbonized polyacetylene and polyaniline nanofibers. In contrast to pristine polyacetylene nanofibers that show vanishing magneto conductance at large electric fields, carbonized polymer nanofibers display a negative magneto conductance that decreases in magnitude but remains finite with respect to the electric field. We show that this behavior of magneto conductance is an indicator of the electric field and temperature dependence of hopping length in the gradual transition from the thermally activated to the activation-less electric field driven variable range hopping transport. This reveals magneto transport as a useful tool to probe hopping lengths in the non-linear hopping regime. For disordered systems, Mott6 first pointed out that the hopping conductivity of the Miller-Abraham’s resistance network, taking into account both tunneling between localized wave functions and thermal activation, can be expressed as7,rhop is the temperature-dependent average hopping length, E is the width of the energy interval near the Fermi level where hopping takes place, and kBT is the thermal energy. In the high temperature limit, transport is dominated by thermally activated nearest neighbor hopping, which results in Arrhenius-like conductivity. However, at lower temperatures, it might be energetically favorable for electrons to hop distances that in average are larger than the nearest-neighbor distance. In this conditions, the average hopping length follows a temperature dependence s = 1/(d + 1) for d dimensional systems, β is a numerical constant and 8. In particular, for the Efros-Shklovskii systems (ES), where the Coulomb interaction is involved in the VRH conduction, the density of states at the Fermi level is modified by the formation of a soft Coulomb gap and the exponent s takes the constant value 1/2 regardless of dimensions10. Further lowering temperature, the conduction reaches to the activation-less regime, where the current-voltage (I-V) is temperature independent and highly non-linear15. In this low temperature regime, the average hopping length follows an electric field F dependence 16. Yet, at the crossover between the thermally activated to the activation-less, electric field driven transport, the hopping length is a function of both the temperature and electric field, and thereby it cannot be determined solely from Variable range hopping (VRH) conduction has been investigated widely in non-crystalline and crystalline materials including amorphous carbonsH = 14 T as a function of bias voltage and temperature. The carbonized nanofibers become essentially amorphous carbon fibers after pyrolysis of polymer nanofibers at 800 °C22 and show characteristics of the ES-VRH conduction in the temperature and electric field dependence of conductivity14. These nano-materials are advantageous14 to study the crossover from thermal to electric field driven transport due to the possibility of applying very large electric fields in realistic experimental conditions. Additionally, because their polymer chain structure is modified during pyrolysis, polymer nanofibers serve as a test bed to explore the effects of polymer structural changes on MC. For PA and PANI nanofibers, pyrolysis at 800 °C results in dehydrogenation and cross-linking of adjacent polymer chains, yielding quasi amorphous, graphite-like carbon fibers22. In its pristine form, polyaniline (PANI) nanofibers display a finite and negative MC independent of the magnitude of the applied electric field. In sharp contrast, pristine polyacetylene (PA) nanofibers display a vanishing magnetoresistance (VMR) at high electric fields, which is attributed to charge being predominantly carried by spin-less topological solitons emerging from the peculiar backbone of PA 28. Therefore, the VMR, (i.e. zero magnetoresistance at high electric fields) of PA nanofibers probes the spin-charge inversion of this material28, which is also important for exploring intrinsic conduction mechanism of conducting polymers33. In contrast to pristine PA nanofibers, both CPA and CPANI nanofibers display a negative MC that decreases in magnitude but remains finite with respect to the electric field. After carbonization of polymer chains, the non-trivial behavior of MC can be understood in the context of VRH, and we find that the electric-field and temperature dependence of MC can be used to probe the electric field and temperature dependence of hopping length. As it will be shown later, the weaker MC at high bias is not merely a consequence of Joule heating. Instead, we show that our measurements can be understood in the context of the wave function shrinkage model9, in which the negative MC is the result of magnetic confinement of localized states.In this paper, we show that the effect of the magnetic field in transport can be used to probe the hopping lengths in ES-VRH systems in the crossover from the thermally activated to the activation-less electric field driven transport, and to quantify the relative effects of temperature and electric field to the average hopping distance. We focus on carbonized polyacetylene (CPA) and polyaniline (CPANI) nanofibers as ES-VRH model systems and investigate their magneto conductance (MC) up to I-V) characteristic at different temperatures of the CPA and CPANI nanofibers devices under study. The typical diameters (length) of the carbonized fibers are 15–80 nm (~10 μm), and their disordered graphite structure has been determined by Raman20 and XRD20 spectra. In the low temperature limit, for temperatures T < ~30 K (~10 K) for CPA (CPANI), the I-V characteristic follows the ES-VRH conduction for bias voltages above the transport gap V = ~2 V (~1 V) for CPA (CPANI), with 15. For the high temperature limit, T > ~30 K (~10 K) for CPA (CPANI), the temperature dependence of transport properties is recovered due to the transition from the field-assisted ES-VRH to thermally activated VRH, with 15. The disordered graphite structure of the carbonized nanofibers, determined by Raman spectra20 and XRD20, supports our interpretation of temperature dependence of currents because the amorphous structure allows the field driven hopping between localized states near Fermi level in a wide range of electric fields without breakdown.Figure I/I = [I (H) − I (0)]/I (0), with I the current through the device and H the applied perpendicular magnetic field. The MC of all our devices is finite and negative in the range of our measurements, with a parabolic magnetic field dependence visible at large magnetic fields. The MC has electric field dependence as well as temperature dependence: at fixed temperatures, the magnitude of MC decreases as the source-drain electric field increases and conversely, at a fixed bias, the magnitude of MC decreases as the temperature increases.Figure 4, polymer nanofibers25, organic semiconductors34, and InSb nanowires35. This behavior has been interpreted within completely different theoretical frameworks depending on materials: for PANI nanofiber networks, decrease of activation energy at high electric field4; for polymer nanofibers, spin-less topological solitons associated with the electron-phonon interaction within the polymer chains25; for organic semiconductors, interactions between charged and uncharged species34; for InSb nanowires, breaking of spin-charge separation in Luttinger liquid in a magnetic field35.The decreasing magnitude of MC with increasing bias voltages has been reported frequently in low dimensional systems such as network of PANI nanofibersI-V hopping regime as well. We consider the wave function shrinkage effect as the effect that explains the behavior of MC taking into account the ES-VRH conduction shown in these systems . The localization lengths in the temperature range 1.5 K ≤ T ≤ 20 K are found to be T0 = 7500 K, and F0 = 1.2 9 V/m from the temperature and electric field dependence of conductivity in the fit to 14. In the CPANI nanofiber, the localization lengths in the range 1.5 K ≤ T ≤ 20 K are of the order of T0 = 2900 K and F0 = 2.5 8 V/m14. The localization lengths except at 1.5 K were almost temperature independent, P < 1 at 1.5 K at low voltages. The obtained values of T0 and localization length translate into higher density of states and easier thermal activation for CPANI compared to CPA. This is consistent with the lower resistance and the lower temperature threshold (~10 K) of the CPANI compared to that of CPA (~30 K) in Fig. I-V appears. We estimated P  – I (1.5 K)]/I (1.5 K), and that of the normalized change of MC at 14 T between 10 K and 1.5 K, – [MC (10 K) – MC (1.5 K)]/MC (1.5 K), of CPA is completely different. The former, [I (10 K) – I (1.5 K)]/I (1.5 K), decreases monotonically as a function of bias; However, the latter, – [MC (10 K) – MC (1.5 K)]/MC (1.5 K), is almost independent of bias. We repeat this for the CPANI nanofiber in Fig. I-V at high bias are not due to Joule heating.As alternative explanations to the observed MC in ES-VRH systems one might consider the spin dependent hopping model, in which the hopping length increases as a consequence of spin alignment in the presence of magnetic fieldIn conclusion, we report temperature and electric field dependence of MC in carbonized polymer nanofibers and analyze it within the model of wave function shrinkage in the ES-VRH conduction. In contrast to the VMR of PA nanofibers, the MC of carbonized polymer nanofibers decreases but remains finite at high electric fields due to the profound change of chain structure after carbonization. The behavior of MC of carbonized polymer nanofibers is explained by the transition in the transport regimes, from thermally activated to field driven transport as the electric field increases, manifested by the variation of the hopping length as a function of electric field and temperature. We evaluate both the localization length and the hopping length and show that the hopping length is electric field dependent in the non-linear regime, resulting in the electric field dependence of MC. Therefore, the measurement of MC at different bias and temperatures in the non-linear VRH is a useful tool to probe the hopping length as a function of electric field and temperature.14. In summary, an aligned PA film was synthesized by exposing acetylene gas of six-nine grade to an aligned nematic liquid crystal containing the Ziegler-Natta catalyst, Ti(O-n-Bu)4/AlEt3 by the gravity-flow method38. PANI nanofibers were synthesized by the rapid-mixing method using aqueous acidic solution of ammonium peroxydisulfate (0.8 mmol in 10 mL 1 N hydrochloric acid) as an oxidant and aqueous acidic solution of aniline (3.2 mmol in 10 mL of 1 N hydrochloric acid) and catalytic amount of p-phenylenediamine (5 mg) as a monomer and promoter for fiber growth, respectively39. The aligned PA film was dispersed in N,N-Dimethylformamide (DMF) with ultra-sonication and drop casted on 6 × 6 mm2 Si/SiO2 (300 nm) substrates and doped by gaseous iodine for one hour which prevents the PA film from decomposition during pyrolysis18. PANI nanofibers were dispersed in solution as synthesized and dropped on Si/SiO2 (300 nm). Pyrolysis of fibers for both PA and PANI nanofibers on Si/SiO2 (300 nm) substrates took place in a tube furnace at 800 °C for one hour under nitrogen flow with 1 °C/min of heating and cooling rate. Ti/Au (5/95 nm) contacts were defined by conventional e-beam lithography for electrical measurements. Magneto transport measurements were performed using an Oxford 14 T superconducting magnet with a Keithley 6517 electrometer in two-probe geometry. Temperature was controlled using a Neocera LTC-21 temperature controller together with a Variable Temperature Insert (VTI).Synthesis, carbonization of PA and PANI nanofibers, and fabrication of the contacts are described in detail in our previous reportThe datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.Supplementary information


Visual inspection with acetic acid (VIA) and Lugol’s iodine (VILI) are used to screen women for cervical cancer in low-resource settings. Little is known about correlates of their diagnostic accuracy by healthcare provider. We examined determinants of VIA and VILI screening accuracy by examiner in a cross-sectional screening study of 1528 women aged 30 years or older in a suburb of Kinshasa, Democratic Republic of Congo.We used a logistic regression model for sensitivity and specificity to estimate the diagnostic accuracy of VIA and VILI, independently performed by nurse and physician, as a function of sociodemographic and reproductive health characteristics.Nurses rated tests as positive more often than physicians . Women’s age was the most important determinant of performance. It was inversely associated with sensitivity  but positively associated with specificity . Increasing parity adversely affected sensitivity and specificity, but the effects on sensitivity were significant for nurses only. The screening performance of physician’s assessment was significantly better than the nurse’s .Age and parity influence the performance of visual tests for cervical cancer screening. Proper training of local healthcare providers in the conduct of these tests should take into account these factors for improved performance of VIA and VILI in detecting cervical precancerous lesions among women in limited-resource settings. Cervical cancer is the third most common cancer diagnosed among women worldwide and ranks seventh among all causes of death, with an estimated 529,000 new cases and 275,000 deaths in 2008 ,2. NearlThe diagnostic performance of VIA and VILI for cervical cancer screening, and determinants of their positivity have been extensively evaluated ,6–12. HoA detailed description of the design, study population, eligibility criteria, data collection methods, and study outcomes of the Congo Community-Based Screening Study is provided elsewhere ,13,14. FWomen were screened by conventional cytology , HPV DNA testing (Hybrid Capture 2), VIA, VILI, and colposcopy. Cytological diagnoses were based on the Bethesda system , i.e., nWe used a method originally derived by Cornfield (1962) to estimate a subgroup risk of coronary heart disease , and latWe chose predictors based on a backward stepwise selection procedure, using an arbitrary p-value of 0.15 and the likelihood ratio test, to accommodate important covariates. We also used judgment based on biological plausibility for variables that could potentially influence the performance of VIA and VILI, e.g., menopausal status. The final models included age , age at first sexual intercourse , number of lifetime sexual partners , history of sexually transmitted diseases , parity , menopausal status (pre vs. post), healthcare provider , history of Pap test , HPV DNA test results , and cytology test results . The disease status variable was based on the results from the colposcopy supplemented with histological verification if a biopsy had been taken . Eight vA non-parametric test developed by Cuzick (1985)  was usedThe mean age of participants was 42.7 years (range: 30–85 years). Among the 1528 women enrolled, nurses reported a positive VIA for 555 (36.3%) and a positive VILI for 401 (26.2%), whereas VIA and VILI positivity according to the physician’s assessment were recorded for 462 (30.2%) and 385 (25.2%) women, respectively. Tables In general, there was a significant difference in performance between the physician and the nurse. For VIA, the sensitivity of the physician’s assessment was 13% higher in absolute terms than the nurse’s (95% CI: 0.09–0.16). The physician scoring was also more specific than the nurse’s . The same was observed for VILI: difference in sensitivity: 16% ; difference in specificity: 1% , favoring the physician assessment. The differences observed across most characteristics show that the physician tended to be more accurate than nurses, with few exceptions.We used the Coughlin’s model approach  to estim+ diagnosis and HPV positivity with a higher viral load were found to be determinants of VIA positivity [Although previous studies have investigated predictors of VIA positivity –11, theysitivity .Our results show variation in nurse- and physician-based VIA and VILI positivity rates, that were also higher, especially for VIA, than previously reported figures –11. VariStudies of inter-rater agreement on the performance of visual inspection techniques for precancerous lesions of cervical cancer are very limited, but good concordance is generally reported. Moderate to substantial agreement for VIA performance was found between test providers ,23,24, wSubjectivity in the interpretation of visual test results by different test providers and high false positive rates are acknowledged limitations of visual inspection screening tests ,12,25. IThe main strength of our study is that it is the first report to use a statistical approach (the Coughlin model) to calculate sensitivity and specificity of VIA and VILI tests while accounting for potential patient characteristics that can influence test accuracy. Moreover, ours is the first to investigate whether the accuracy of VIA and VILI tests depends on the test provider, while simultaneously controlling for other patient characteristics. Other strengths of this study include its population-based design, high response rate, the fact that cytopathologists and pathologists were blinded to the results of the screening tests, and that all women underwent colposcopy, thus minimizing the likelihood of verification bias which arises when the only individuals to undergo the reference standard test for verification of disease are those who have screened positive ,27.The diagnostic accuracy of VIA and VILI tests performed by nurse and physician were significantly related to being younger, having high parity, pre-menopausal status, HPV positivity, and cytology with an ASC-US cut-off status. Our results suggest that improved training of healthcare providers (prior to their being deployed as screeners) to take these determinants into account will enhance the performance of VIA and VILI in detecting cervical precancerous lesions among women in low-resource settings. To improve their diagnostic accuracy, more training of the nurse on case definition and interpretation of definite aceto-white cervical epithelium of VIA test is also warranted.S1 Table(XLSX)Click here for additional data file.


The purpose of this study was to investigate the usefulness of intracystic MRI features for detection of severe cyst infection that is usually refractory to antibiotic therapy alone in patients with autosomal dominant polycystic kidney disease.Seventy-six patients (88 episodes) with positive cyst cultures treated from January 2006 to December 2013 were enrolled as the cases for this case–control study, while 147 patients who continued to attend our hospital from January 2011 to December 2013 and did not have cyst infection diagnosed during that period were enrolled as the controls. Intracystic MRI findings were investigated.3). A cyst diameter > 5 cm was useful for detecting severely infected cysts that needed drainage, and specificity was increased by combining the other four MRI findings with a cyst diameter > 5 cm.At least one of four intracystic MRI features  on diffusion-weighted images (DWI), fluid-fluid level, wall thickening, or gas) was found in all of the cases, but such findings were also detected in some controls. Intracystic gas was specific for cyst infection, but its sensitivity was only 1.1 %. A high intracystic SI on DWI showed a sensitivity of 86.4 %, but its specificity was lower at 33.3 %. Both the specificity and sensitivity of a fluid-fluid level or wall thickening were about 80 %. However, the specificity of these MRI features decreased as total liver and kidney volume (TLKV) increased, falling to 65.8 % in patients with organomegaly  contains supplementary material, which is available to authorized users. Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited renal disorder and the most common monogenetic cause of end-stage renal disease (ESRD) . Cyst inThis retrospective case–control study was reviewed and approved by the ethics committee of Toranomon Hospital. All clinical information was obtained from the medical database of Toranomon Hospital . We evaluated the sensitivity and specificity of the four intracystic MRI features in our criteria for detecting infected cysts by comparing their frequency between the cases and controls. We also analyzed the MRI features of the cysts in four groups based on total liver and kidney volume (TLKV) quartiles that approximated the quartiles of the controls. We also counted the number of cysts with a diameter >5 cm, because antibiotic therapy is less effective and drainage is more likely to be required for infected cysts with a diameter exceeding 5 cm , 5.Only adult patients (20 or more than 20 years old) were enrolled in this study. All patients admitted to Toranomon Hospital with a diagnosis of cyst infection from January 2004 to March 2014 were identified by entering the key words cyst infection for the diagnosis at discharge or the complication during hospitalization. Among them, all patients who underwent cyst drainage and had positive cyst fluid cultures were enrolled as cases in this study. As a result, all of the patients enrolled might have had severe cyst infection since bacteria were not eliminated by prior antibiotic therapy . In order to exclude recurrence of previously undertreated or suppressed cyst infection, we excluded episodes that occurred within 3 months after discontinuing antibiotics for both positive cyst culture Fig. . All ADP2; slice thickness, 9 mm; gap, 1 mm. T2WI were obtained with the half Fourier single shot turbo spin-echo (HASTE) sequence using the following parameters: repetition time/echo time, 1,000 ms/83 ms; flip angle, 75°; acquisition time, 15 s; number of signals acquired, 1; matrix, 256 × 256; field of view, 81.25 cm2; slice thickness, 9 mm; gap, 1 mm. DWI were acquired by the single-shot echo-planar imaging sequence with a parallel imaging technique and the following parameters: repetition time/echo time, 2,400 ms/90 ms; acquisition time, 15 s; number of signals acquired, 1; matrix, 350 × 400; field of view, 87.5 cm2; slice thickness, 9 mm; gap, 1 mm.Abdominal MRI was performed in all patients with suspected cyst infection. In the controls, abdominal MRI was usually performed to evaluate organ volume. We obtained T1-weighted images (T1WI), T2-weighted images (T2WI), and diffusion–weighted images (DWI) in the transverse and sagittal projections in all patients. None of the patients underwent gadolinium-enhanced MRI because of the high prevalence of renal dysfunction. MRI was performed with a 1.5-T apparatus  and a body phased-array coil. Patients remained in the supine position throughout the examination and all images were obtained with breath holding. T1WI were obtained with the fast low angle shot (FLASH) sequence using the following parameters: repetition time/echo time, 168 ms/2.26 ms; flip angle, 75°; acquisition time, 15 s; number of signals acquired, 1; matrix, 325 × 400 voxels; field of view, 81.25 cmThe MRI findings were analyzed by three different readers  who each had more than 10 years of experience. Judgment of the intracystic SI on DWI, the presence of a fluid-fluid level, the cyst wall thickness, intracystic gas, and intracystic changes was done by complete consensus of all three readers. Because the readers had different specialty backgrounds, we did not calculate kappa statistics in this study. The width of each cyst wall was measured and wall thickening was defined as being present when the width was ≥3 mm. Intracystic high SI on DWI was counted even if it was a small cyst whose diameter < 5 mm. Comparison of the SI ratio between infected cysts and skeletal muscle was done as reported previously . If draiAcute abdominal pain/back pain, gross hematuria, and high intensity on T1WI are suggestive of acute intracystic bleeding. In patients with such symptoms/findings, we usually performed abdominal CT to more clearly differentiate between cyst infection and intracystic hemorrhage. We did not perform drainage of cysts with acute hemorrhage.a × b × c × π/6), where a is the maximum length of the kidney and b and c are the maximum widths in two transverse dimensions. MR images obtained at a slice interval of 1 cm were analyzed using Synapse software (Fujifilm Company) to measure the liver area (cysts plus parenchyma), and the liver volume was calculated as the sum of the hepatic area on each slice. Then the TLKV was calculated as the sum of the kidney volume and the liver volume.Renal volume was calculated on MR images by using the formula for an ellipsoid  analysis. Internal validity for area under curve (AUC) of ROC analysis for each diagnostic feature was assessed by calculating the 95 % confidence interval (95 % CI) by the bootstrap resampling technique .Results are expressed as the mean ± SD for data analyzed by parametric tests and as the median with interquartile range for data analyzed by non-parametric tests. A probability (P) value of less than 0.05 was considered to indicate significance. For quantitative variables, differences between groups were assessed by Student’s All statistical analyses were performed with the SPSS Statistics 18.0 statistical software package .A total of 279 patients were admitted to our hospital with a diagnosis of cyst infection 615 episodes) during the period from January 2006 to January 2014 Fig. . Drainag episodesOur MRI diagnostic criteria for cyst infection were highly sensitive because at least one of the four imaging features was seen in every patient with cyst infection. Intracystic gas was specific for cyst infection, so we can make a diagnosis of infected cyst whenever intracystic gas is detected. In addition, when an intracystic fluid-fluid level or wall thickening is seen, the specificity or sensitivity for diagnosis of infected cyst is about 80 % Table . ROC ana3, the specificity of a fluid-fluid level or wall thickening was only 65.8 %, so these features alone are not useful for diagnosis of cyst infection. In these patients with a TLKV > 8500 cm3, the sensitivity of a fluid-fluid level or wall thickening was 72.2 %, for cysts with a diameter > 5 cm, but the specificity was lower at 76.3 %  had more than 5 cysts with at least one of the four features of infection Fig. .Fig. 4CoAn intracystic high SI, fluid-fluid level and sequential changes were only seen on DWI but not on T1WI and T2WI in some cases. One of the reasons for this difference might be that contrast ratio of DWI is higher than that of T1WI or T2WI. Because DWI are useful for evaluating intracystic findings, we suggest DWI should be added to routine MRI in patients with ADPKD. Enhanced CT is associated with exposure to radiation, renal toxicity, and allergy, while enhanced MRI using gadolinium-containing contrast medium is associated with nephrogenic systemic fibrosis, so these imaging methods are not suitable for routine screening. Because it avoids these disadvantages, plain MRI might be suitable as a routine screening method in ADPKD patients with huge kidneys. If we detect abnormal cysts, we should consider diagnoses such as cyst infection, intracystic hemorrhage, or neoplasm. This protocol could potentially improve the outcome of ADPKD patients, but a prospective multicenter study is needed to confirm its usefulness. The optimum interval between abdominal MRI examinations is also controversial, and an appropriate interval should be determined. The present study revealed that intracystic changes on MRI are more likely to occur as the organ volume becomes larger, so we should probably perform MRI more often as organ volume increases.A limitation of this study is that this was a retrospective study performed at a single center. We enrolled controls who were without cyst infection during the study period according to our medical records, but some of these patients might have been treated for this condition at other hospitals. In addition, selection bias might have occurred because the attending physicians decided whether or not to perform abdominal MRI in the controls. A positive result of cyst contents culture was needed for enrollment of the cases in this study, so our subjects might have had severe cyst infection since bacteria were not eliminated by prior antibiotic therapy. However, it is clinically important to be able to correctly identify the infected cyst in patients with severe cyst infection, because drainage should be performed. The frequency of cysts with a diameter >5 cm was much higher among cases than controls, possibly due to selection bias, since infection may be more likely to become severe if the cyst is large and it could be more technically difficult to drain cysts with a diameter < 5 cm. We determined the cyst/skeletal muscle ratio, but this is less accurate than an apparent diffusion coefficient (ADC) map. However, a longer time is needed to make an ADC map, which is often difficult in patients with ADPKD who can only remain in the supine position for a brief period due to their organomegaly. The MRI protocol that we employed was relatively convenient for the patients, but obtaining 10 mm slices may have reduced the sensitivity of imaging. Finally, the number of patients was not so large, so further investigation is needed.3). A cyst diameter >5 cm was useful for detecting infected cysts that needed drainage, and specificity was increased by combining a cyst diameter > 5 cm with the four MRI features of cyst infection. We could identify most cases of severe cyst infection that required drainage by combining the four MRI features with abdominal pain at the same location plus changes from previous MRI findings and a cyst diameter >5 cm. Thus, MRI with DWI is useful for detecting severely infected cysts in ADPKD patients.A fluid-fluid level or wall thickening on MRI were useful for detecting severely infected cysts in ADPKD patients, showing a sensitivity and specificity of about 80 %. However, the specificity decreased as TLKV increased and was only 65.8 % in patients with massive organomegaly (TLKV > 8500 cm


Background. Birth preparedness program was designed to enhance skilled birth attendance and postpartum checkups of women in a developing country to reduce the three delays that lead women and neonates to death and disability. However, the relationship between birth preparedness with skilled birth attendance and postpartum checkups among mothers is not well studied. Therefore this study is intended to assess the association between birth preparedness and skilled birth attendance and postpartum checkups. Methods. A community based cross-sectional study was conducted from March to April 2014. Eight out of 22 Kebeles were selected using probability proportional to size sampling method. Seven hundred and forty-five mothers were selected randomly from the sampling frame, generated from family folders obtained from health posts. Data was collected using pretested questionnaire by face-to-face interview. Data was entered into EpiData version 3.1 database and analyzed by SPSS version 16. Result. Out of 745 sampled mothers 728 (97.7%) participated in the study. One hundred and twelve (15.4%) and 128 (17.6%) mothers got skilled birth attendance and received postpartum checkups for their last child, respectively. Birth preparedness, educational status of women and their husbands, and antenatal care visits of mothers were found to be predictor of skilled birth attendance and postpartum checkups. Mothers well prepared for child birth were 6.7 times more likely to attend skilled birth attendance [AOR = 6.7 (2.7–16.4)] and 3 times more likely to follow postpartum checkups [AOR = 3.0 (1.5–5.9)] than poorly prepared mothers, respectively. Travel time to reach the nearest health facility was found as predictor for postpartum checkups of mothers; mothers who travel ≤ 2 hours were three times more likely to follow postpartum checkups than mothers who travel > 2 hours (AOR (95% CI) = 3.4 (1.5–7.9)). Conclusion and Recommendation. Skilled birth attendance and postpartum checkups were low. Encouraging women to attend recommended antenatal care visits and providing advice and education on birth preparedness and obstetric danger signs are important interventions to increase skilled birth attendance and postpartum checkups. Child birth is an event celebrated for many thousands of women each day, yet child bearing is an event of maternal and neonatal death and injury occurrence as a result of sudden and unpredictable acute obstetric problems –5. GlobaThaddeus and Maine outlined three delays that lead to maternal death and disability; the first delay lies in deciding to seek care when complication occurs; the second is delay in reaching care and the third delay is in receiving care . NonetheThe International Conference on Population and Development (ICPD) 1994), the Fourth World Conference on Women in Beijing 1995), and the Millennium Development Goals (MDG) (2000) recommend skilled birth attendant and postpartum checkups as key intervention to reduce maternal mortality –15. WHO 994, the , and theMaternal and Neonatal Health (MNH) Program of JHPIEGO an affiliate of John Hopkins University developed birth preparedness program to tackle the three delays that lead to maternal death. Birth preparedness is the process of planning for normal birth and anticipating the actions needed in case of an emergency. It is a strategy that anticipates, promotes, and motivates women for timely use of SBA and PPC. Timely use of SBA reduces delays in obtaining care and possible occurrence of birth complication and if complication occurs it will be immediately managed. A birth preparedness plan includes identification of the following elements: identifying a skilled birth attendant; identifying the location of the closest appropriate care facility; funds for birth related and emergency expenses; transport to a health facility for the birth and obstetric emergency; arranging clean material for safe delivery and foods; and identification of compatible blood donors in case of emergency complication , 27–34.To the best of our knowledge there was no study conducted that assesses the association between birth preparedness and skilled birth attendant and postpartum period in Ethiopia. This study aimed to assess birth preparedness and its association with skilled birth attendance and postpartum checkups among mothers in south Ethiopia. We hypothesize that well-birth-prepared mothers are more likely to attend skilled birth attendant and follow postpartum care than those poorly prepared.A community based cross-sectional study was conducted in Gibe Wereda, South Ethiopia. Eight rural Kebeles were selected from 22 using probability proportional to size sampling method. Sampling frame was developed from family folder found at health post from each selected Kebele and all women who gave birth in the last 6 months prior to the study were registered; then sample was allocated proportionally to their size of source population. Finally 745 mothers were selected randomly and interviewed from March to April 2014.Sample size was calculated using two population proportion formulae using Epi Info version 7 Software based on the following assumptions: expected proportion of skilled birth attendance among birth prepared and non-birth-prepared women were 76.3% and 63.7%, respectively (20), confidence interval 95%, power = 80%, and ratio of 4 : 1 non-birth-prepared to birth prepared mothers. This study included mothers who are permanent residents of the selected Kebeles and mothers who gave birth 6 months preceding the study.A structured questionnaire was adapted from the survey tools. The questionnaire was developed in English version; then it was translated into Amharic and Hadiyissa versions and back-translated to check its consistency in translations by different individuals. Questionnaire was pretested on 38 mothers and findings and experiences from the pretest were utilized to modify the tools. Sociodemographic and reproductive characteristics of mothers were collected using face-to-face interviews by five health extension workers (HEW) in the study participants' homes and two diploma graduate nurses supervising day-to-day activities.Skilled Birth Attendance. WHO defines a skilled birth attendance as delivery attended by an accredited health professional—such as a midwife, doctor, or nurse—who has been educated and trained to proficiency in the skills needed to manage normal (uncomplicated) pregnancies, child birth, and the immediate postnatal period and in the identification, management, and referral of complications in women and newborns; any birth attended by traditional birth attendant, relative or friend, or any other person who is not a health professional with midwifery skills based on the respondent's description was classified as unskilled birth. Postpartum Checkups. At least a single postpartum checkup during postpartum period, periods beginning after the delivery of the placenta and continuing until 42 days after child birth, is considered as women attended postpartum checkup. Birth Preparedness Index. Principle Component Analysis (PCA) was used to construct birth preparedness index by using various components suggested by MNH Program of JHPIEGO , arranged food, and other arrangements). Birth preparedness level was measured based on eight variables, each variable was assigned a weight (factor score) generated through principal component analysis, and the resulting birth preparedness scores was standardized in relation to a normal distribution with mean zero and standard deviation one. The score distribution was used to categorize birth preparation into poor, moderate, and well. The new variable (birth preparedness index) scale is varying from “poor” to “well” preparedness and further analysis was carried out by this variable. Knowledge of Obstetric Danger Sign. Women were considered as well knowledgeable about obstetric danger signs related to pregnancy and child birth if they scored equal and above the mean of 17 knowledge questions and if less than mean they were considered as poorly knowledgeable. Wealth Index. It is a composite measure of the cumulative living standard of a household. The wealth index is calculated using easy-to-collect data on a household's ownership of selected assets, such as television, radio, livestock, furniture, and farm land. Generated with a statistical procedure known as principal components analysis, the wealth index places individual households on a continuous scale of relative wealth. Each household asset for which information is collected is assigned a weight or factor score generated through principal components analysis. The resulting asset scores are standardized in relation to a standard normal distribution with mean zero and standard deviation one. These standardized scores are then used to create the break points that define wealth index as lowest, second, middle, fourth, and highest.P < 0.05.Data was cleaned and entered into EpiData version 3.1 database and analyzed using SPSS version 16.0 statistical Software. Bivariate and multivariable logistic regression analysis was used and strength of statistical association was assessed by adjusted odds ratios and 95% confidence intervals and statistical significance were considered at The study was financially supported and ethical clearance was obtained from Jimma University College of Public Health and Medical Science and permission was also obtained from the local administrative units. Informed verbal consent was obtained from all the study participants.A total of 728 participated in the study with response rate of (97.7%). The majority of respondents were between 25 and 34 years of age, married, followers of protestant religion, housewives, and Hadiya by ethnicity and housewives. More than half (53.6%) of the mothers did not attend formal education; 248 (34.1%) attended primary and 90 (12.4%) attended secondary and above education. Almost all respondents (723 (99.3%)) travel on foot and 589 (80.9%) travel greater than two hours to reach the nearest health center. Regarding respondents' husbands' educational and occupational status, 299 (42.1%) did not attend formal education and 542 (76.4%) were farmers. Equal proportion (19.6 to 20.2%) of mothers were in lowest, second, middle, fourth, and highest wealth groups .Regarding previous obstetric characteristics of the mothers, 115 (15.9%) had one and more stillbirth experience and 322 (52.2%) of mothers had experienced at least single obstetric complication. Regarding birth space 368 (59.7%) of mothers were two and less than two years of birth interval between previous and last child and 259 (35.6%) had 2-3 times pregnancies. With respect to previous mode of delivery, 600 (97.1%) had normal delivery .Concerning the last pregnancy characteristics, more than half 423 (58.2%) of mothers planned their last child pregnancy. The majority (563 (77.3%)) attended antenatal visits, but 164 (22.5%) did not attend; 501 (68.8%) of mothers were advised about birth preparedness tools by health professional during their ANC visits and about 118 (16.2%) mothers experienced pregnancy complication. The majority, 613 (84.2%), of mothers delivered at home and 89 (12.2%), 23 (3.2%), and 3 (0.4%) of mothers delivered at health center, hospital, and health post, respectively, and 311 (42.7%) decided their place of delivery by themselves. Out of 728 mothers, 112 (15.4%) of deliveries were assisted by skilled birth attendant , and 128 (17.6%) of mothers attended at least one postpartum checkup after their last delivery .As to knowledge on obstetric danger signs, more than half 415 (57.0%) and 313 (43.0%) of the mothers had good knowledge and poor knowledge about danger signs that occur during pregnancy, delivery, and postpartum period, respectively .Pertaining to birth preparedness status of mothers, As shown in As shown in Husband's educational status was also significantly associated with postpartum checkups of mothers. Mothers whose husbands' educational status secondary and above were 2.1 times more likely to follow postpartum checkups than whose their husbands' educational status was informal education [AOR = 2.1 (1.1–3.3)].Mothers who attended four or more antenatal care visits and had knowledge of danger signs during pregnancy and child birth were more likely to follow postpartum checkups than mothers who did not attend antenatal care and had poor knowledge [AOR = 3.9 (1.5–10.2)] and [AOR = 1.9 (1.1–3.3)], respectively. Those mothers who travelled ≤ 2 hours from their home to health center were 3.4 times more likely to follow postpartum checkups than those who travelled more than two hours [AOR = 3.4 (1.5–7.9)].This study assessed the association of birth preparedness with skilled birth attendance and postpartum checkups of mothers in rural area. Birth preparedness becomes predictor of skilled birth attendance and postpartum checkups of mothers. Well-prepared mothers for child birth were more likely to attend skilled delivery and follow postpartum checkups than those poorly prepared. This implies that the birth preparedness components, saving money, arranging transport, identifying skilled birth attendant, and arranging blood donors, are important factors to get health facility. Saving money is important for costs incurred. Arranging transport is important in place where people living rural and far from health facility. Identifying skilled attendant is also important for the psychological confidence and arranging blood donors is also important during emergency bleeding. Therefore, this readiness and preparation for child birth will make mother utilize health service. The plausible reason might be the fact that also when mothers do not prepare well, they bother as labor begins in identifying skilled provider, identifying place of delivery, searching for money for incurred cost, finding transportation, and other things which may contribute to high home delivery. This finding was consistent with the study conducted in Nepal, rural Uganda, and in Madhya Pradesh, India, that revealed prepared mother's use of health facility to get child birth , 31, 32.Educational status of the mothers was significantly associated with skilled birth attendance and postpartum checkups of the mothers. This study was consistent with research done in Ethiopia and Nepal , 22, 25.Another predictor of skilled birth attendance and postpartum checkup was antenatal care of mothers. This could be due to the fact that as mothers attended ANC visits repeatedly they had enough contact time with health professionals which creates good opportunity for advice on birth preparation and on importance of birth preparation, SBA, and PPC. This will empower mothers to seek health service. This study revealed that ANC visit was about 77.7%, but SBA and PPC were very low; it can be considered as missed opportunity; this may indicate that the information, advice, and service delivered to mothers at health institution during ANC visit may be in doubt. This finding was in line with study conducted in parts of Ethiopia , 25, 26.When mothers made decision of place of delivery in consultation with their husbands, the probability of getting birth assisted by a skilled birth attendant was high. However, when women made the final decision alone, the likelihood of getting birth assisted by SBA was low. This might be due to the fact that when mothers decide their place delivery with consultation of their husband, they may get financial and psychological support. Ensuring women's autonomy in deciding place of delivery alone may not guarantee maternal health service utilization. Similarly this finding was consistent with the study done in Southwestern Uganda in 2011 , 26.Husbands' educational status was significantly associated with skilled birth attendance and postpartum checkups. Women whose husbands had secondary and above education were more likely to attend skilled birth attendant and postpartum checkups than those who did not attend formal education. This may be possibly a result of the fact that educated husbands might be aware of the danger events occurring during child birth and importance of skilled birth attendance and attending postpartum checkups. This finding was parallel with that of a study done in Munisa Wereda, Oromia region .Knowledge of danger signs during pregnancy and child birth of the mothers was found to be significantly associated with postpartum checkups. Mothers who had good knowledge were more likely to follow postpartum checkups than mothers who had poor knowledge even after controlling the possible confounder. This may be due to the fact that, when mothers were aware of danger signs during pregnancy, they know the possible adverse event happening during postpartum period; this encouraged mothers to follow PPC. This finding was consistent with the study conducted Arsi Zone, Oromia region, in 2011 and Bahirdar, Amhara region, in 2012 , 26.Travel time to reach the nearest health institution was found statistically significant. Mothers who travel ≤ 2 hours were more likely to follow postpartum checkups than mothers travelling > 2 hours to reach the nearest health center. The possible explanation for this is that postnatal period is a period where women's body is sensitive and weak; as a result, physical proximity of health institution was determining factor in case of this study where most of study participants (99%) were travelling on foot. Mothers living in closer proximity to modern health services were more likely to receive services from health personnel for the treatment of life-threatening and high-risk conditions during the postnatal period. This finding was in line with EDHS, 2011, report .Mothers with history of stillbirth were more likely to attend skilled birth attendant than mother who did not experience stillbirth in the study area, even it was statistically significant. This might be due to the fact that mothers who had experienced stillbirth may not want suffering and pain of life loss during child birth; for this reason the possibility of mothers to get skilled birth attendant would be increased among women who had experienced stillbirth than those who had not experienced stillbirth. This result was consistent with the study conducted in in Dodota Wereda, Oromia region .The potential limitations of this study should be considered. The community based sampling strategy, high response rate, and large sample size reduced the possibility of selection bias. Since this study was cross-sectional study there could be temporality bias. However, in preparation of the data collection tool and during interviews, mothers were asked to tell history of exposure status before the occurrence of the outcome. Second, since this study inquires past exposure status of mothers, there could be recall bias. To minimize inaccurate reporting, study participants were selected within six months after delivery. Third, validation of self-report information was not done by comparison to medical records due to inaccessibility of individual files from health facilities. Finally, the influence of specific birth preparedness components on the outcomes was uncertain since, birth preparedness was composite variable derived by PCA.In this study percentage of skilled birth attendance and postpartum checkups was very low. However, more than three-fourth of mothers attended antenatal cares. This may create good opportunity by health professionals and health institutions to advise mothers to prepare for child birth and danger signs, attend SBA, and follow PPC. Therefore it is recommended to use this golden opportunity to advocate the importance of skilled delivery and postpartum checkups, and further study should be done on maternal health service providers and health institution characteristics.


The best method of gestational age assessment is by ultrasound in the first trimester; however, this method is impractical in large field trials in rural areas. Our objective was to assess the validity of gestational age estimated from prospectively collected date of last menstrual period (LMP) using crown-rump length (CRL) measured in early pregnancy by ultrasound.n = 353) were enrolled for ultrasound follow-up to measure CRL. We compared interview-assessed LMP with CRL gestational age estimates and classification of preterm, term, and post-term births.As part of a large, cluster-randomized, controlled trial in rural Bangladesh, we collected dates of LMP by recall and as marked on a calendar every 5 weeks in women likely to become pregnant. Among those with a urine-test confirmed pregnancy, a subset with gestational age of <15 weeks (P < 0.05). Lin’s concordance correlation coefficient was good at ultrasound [0.63 ] and at birth [0.77 ]. Validity of classifying preterm birth was high but post-term was lower, with specificity of 96 and 89 % and sensitivity of 86 and 67 %, respectively. Results were similar by parity.LMP-based gestational age was higher than CRL by a mean (SD) of 2.8 (10.7) days; differences varied by maternal education and preterm birth  contains supplementary material, which is available to authorized users. Globally, an estimated 14.9 million preterm births occurred in 2010 . Key limStudies comparing LMP to ultrasound dating have been typically reported in high-income countries where the resources exist for screening most women –7; howevIn rural northwestern Bangladesh, we conducted a large cluster-randomized trial of antenatal micronutrient supplementation to examine outcomes of low birth weight, preterm birth, and small-for-gestational age . Becausen = 44,567)  by LMP and 73.3 (12.9) days [10.5 (1.8) weeks] by CRL (.5 days [n = 333) and at live birth was 2.5 (10.5) days (n = 315).Using validity measures, gestational age by LMP was in good agreement with CRL at the ultrasound visit, with a Pearson’s correlation of 0.63, bias correction factor of 0.98, and Lin’s concordance correlation of 0.63 Table . For valWe examined the difference in gestational age estimates (LMP-CRL) by maternal and infant characteristics and observed a range of differences from −1.6 to 4.3 days across characteristics , the preterm birth rate was closer to that seen in the parent trial at 13.9 %. Other differences such as higher education, etc., in this validation group may also explain the difference between preterm birth rates with the larger study.This study validates the use of prospectively collected LMP for estimating gestational age in a low-income, rural setting in Bangladesh, with preterm birth and SGA rates among the highest globally . UniquelOverall, the characteristics of women in the substudy were similar to the whole trial. Exceptions include that literacy was higher and households having electricity was lower in the substudy compared to the parent study. We were unable to explore all the potential reasons for this paradox; however, availability of schools does not necessarily correlate with availability of electricity to households, and a mother’s education would have occurred while at her parent’s household and not her (current) husband’s household. A final concern was that the sensitivity and specificity for post-term births was found to be somewhat low, and its prevalence was highly inflated when using LMP to estimate gestational age. It is not clear why this occurred, other than the difficulty of predicting a very narrow classification range .The goal of this research was to investigate the use of LMP as an accurate estimate of gestational age in large field trials such as ours, especially using rigorously collected menstrual dates in a free-living populations, and with the use of a calendar as an aid. Although conducted in a small sample, we also found that the use of a durable, portable, battery-operated ultrasound machine was feasible in a rural setting with limited access to electricity. There was wide acceptance of the measurements by the community, and the study participants considered the procedure safe.Our sensitivity and specificity estimates of LMP were similar to or better than those reported in two US studies and one in Brazil. In a state-wide study of births in California, Dietz et al. reported a sensitivity of 64 % and a positive predictive value of 59 % for classifying preterm using LMP compared to ultrasound . SimilarFirst trimester CRL, as used in this study, is considered the best measurement for gestational age determination , as it iWe expected that measurements could also be different based on maternal characteristics, especially those that could impact a woman’s record of LMP. We found that LMPs reported by better educated women had better agreement with CRL, which agrees with another US study . PerhapsOur community-based, prospectively collected LMP was a valid measure for estimating gestational age and preterm rates in a low-income, low-education, rural setting. This result is important as our parent trial found a significant reduction in the LMP-based preterm birth rate with multiple micronutrient supplementation . As well


The distribution of birth intervals can be used to draw attention to important characteristics of dynamics of fertility process. The main objective of this paper is to examine the effects of socioeconomic, demographic and proximate determinants on the length of birth intervals of women of Bangladesh and also to see whether the effects are changed over the years.Birth intervals can be considered as correlated time-to-event data because two or more birth intervals could correspond to a single mother. Moreover, women from the same neighborhood usually share certain unobserved characteristics, which may also lead to correlated time-to-event data . A parametric random effect (frailty) model is used to analyze correlated birth interval data obtained from three Bangladesh Demographic and Health Surveys .The results show that alongside different socioeconomic, demographic determinants, unobserved community and mother effects have considerable impact on birth interval in Bangladesh. However, the effects of different factors on birth interval changes in a small scale over the duration of 2004–2011.Efficient policy is a priority for promoting longer birth spacing and achieving a decline in fertility. Fertility is a principal component of population dynamics that determines the structure of the population of a country. Analysis of birth interval (time between two successive live births) is more susceptible method for measuring fertility compared to the other methods , 2 and iBirth intervals can be considered as correlated time-to-event data because a mother could experience repeated occurrence of the same event (childbirth). Duration between two successive live births, and that is between the last live birth and the interview date are considered as closed (event time) and open (censoring time) birth intervals, respectively.Among the very few published papers on birth interval dynamics in Bangladesh, Zenger  studied Different demographic and socioeconomic characteristics are found to be associated with the distribution of the length of birth interval. For example, mother’s age at the birth and the birth order (parity) of the index child have potentially different effects on birth intervals . SurvivaThe main objective of this paper is to identify important factors for the distribution of the length of time intervals and also to examine whether these effects are changed over time. This will help understanding the birth interval dynamics as well. Two different parametric frailty models have been considered for modeling the birth interval: one models cluster effects in mother and another in community level to explore the unobserved heterogeneity. The paper is organized as follows: Section “tij be the birth interval corresponding to the jth child in the ith cluster and δij is the corresponding censoring indicator . For the jth subject of the ith cluster, the hazard function at time t is defined according to a proportional hazards model with a random effect (frailty) as Let h0(t) is the baseline hazard function, ui is the unobserved frailty term, and Xij is the p-dimensional vector of covariates and β is the corresponding p-dimensional vector of regression coefficients.where u’s) are considered as missing observations. On the other hand, for some specific choices of parametric model for the baseline hazrd function, the frailty model (h0(t)=γtγ−1/αγ, α>0, γ>0. The parametric baseline hazard function not only makes the estimation of model parameters easier, but also describes explicitly the effect of the frailty on hazard ratios over time.As in the proportional hazards model, the form of the baseline hazard function can either be unspecified or be modeled using a parametric function. The method of estimating frailty model  depends ty model  can be eThe choice of the frailty distribution is very important and different frailty models have been suggested in the literature , 23. ThoE(U)=1 and Var(U)=θ. The frailty distribution parameter θ provides information on the variability of the population of clusters and a large value of θ indicates that there is a higher degree of heterogeneity among the clusters, and a strong association among the observations within a cluster. This association can be quantified by Kendall’s tau, which can be expressed as a function of frailty distribution parameter θ as τ=θ/(θ+2).with ui, the likelihood function for the ith cluster is then given by In the parametric setting, estimation of parameters is based on the marginal likelihood in which the frailty terms have been integrated out by averaging the conditional likelihood with respect to the distribution of frailty. Condition on the frailty hij(· | ·) is defined in (h0(t) has already been is defined as a function of the vector of parameters ϕ=′. It follows that, the marginal likelihood function for the ith cluster is where the hazard function fined in , the corLm,i in  correspond to the maximum of the marginal log-likelihood function lm is defined in  of the years 2004, 2007 and 2011 have been analyzed in this paper. Demographic and Health Surveys (DHSs) have been conducted in many developing countries of the world for some years now, and different national and sub-national indicators obtained from such surveys have been used by the respective governments for planning short- and long-term policies. These surveys are implemented through a joint efforts of the respective government, Macro International, and USAID, and a multistage stratified cluster sampling was used to select sampling units for each of these surveys. For Bangladesh, each of the administrative divisions is divided into 12 strata  and each of the stratum consists of a number of clusters. At the first stage of the sampling, 361 clusters were selected from the available strata and in the second stage, about 30 households were selected from each of the selected clusters using a systematic random sampling method. A total of 10,523, 10,461 and 17,511 households were occupied in the samples from the sampled households of the years 2004, 2007, and 2011, respectively. A total of 11,440, 10,996, and 11,832 ever-married women from the sampled households were interviewed to collect data for the years 2004, 2007, and 2011, respectively. Information on fertility, awareness of and use of family planning methods, nutritional status of women and young children, childhood mortality, maternal and child health, among others were collected from these surveys.In this study, women who have at least one birth in preceding five years of the respective survey years were selected from the BDHS  data and all birth intervals corresponding to the selected women were used in the analysis. As mentioned in the Section 1, birth intervals could be either open-ended (duration between last birth and interview date) or closed (duration between two successive live births). By considering open-ended and closed birth intervals as censored and event time, respectively, birth intervals are considered as time-to-event data in this paper. Among the important covariates for modeling birth intervals that were reported in earlier studies , those aTables In addition, the proportion of mothers from the poor socioeconomic class remained almost the same over the survey years (about 40 %) and the proportion of poor mothers with four or more children decreased about 10 % (from 36 to 26 %) over 2004–2011. The proportions of mothers from the urban region were 31 %, 36 %, and 32 %, respectively for the years 2004, 2007, and 2011. For the rural region, proportion of mothers with four children decreased from 17 to 10 % over the survey years. The results reveal that the percentage of mothers with more than four children decreased in all six administrative divisions over the study periods.The exploratory analysis described in the previous section provides the differentials observed in the various socioeconomic and demographic characteristics associated with the women selected in this study. To assess the effects of random frailty term in identifying important factors for correlated birth intervals of Bangladeshi women, three parametric proportional hazards models are considered: Model I (without any frailty term), Model II (mother as the only frailty term), and Model III (community or cluster as the only frailty term). The same set of covariates, namely mother’s age at first birth, parity, family composition, survival status of previous child, mother’s education, wealth index, residence, administrative division, and survey year, are considered for each of the three models. To examine the time trend of the effects of different covariates on birth interval, the interaction of survey year with mother’s age at first birth, family composition and survival status are considered for each of the three models. Moreover, both the linear and squared term of the mother’s age at first birth is considered in all three models. The Models I–III are estimated using the pooled data obtained from three BDHS surveys of the years 2004, 2007, and 2011.Table The fit of Model II shows that both the linear and squared effects of the maternal age at first birth are significant, which indicate that initially the likelihood of next birth increases as the mother’s age at first birth increases and after a certain age at first birth, this likelihood starts decreasing. The estimated age at the first birth corresponding to the maximum risk of the next birth are 17.58, 17.83, and 18.08 years for 2004, 2007, and 2011, respectively. Parity is found to be significant and the likelihood of the next birth decreases as parity increases.The birth interval tends to be significantly longer for higher educated mothers compared to mothers with primary or less education, which indicates that maternal education is an important determinant to explain the birth interval differentials. More specifically, mothers with no formal education tend to have shorter intervals between successive births  than their counterparts with higher education. Moreover, mothers with primary education have 44 % more likelihood of the next birth compared to the higher educated mother. The effect of year indicates that the likelihood of successive birth is decreasing with the change of time.Family composition is an important predictor for the distribution of the duration of birth intervals. Mothers with one child (either a boy or a girl) are more likely to have the next birth compared to the mothers with a balanced number of children (one girl and one boy) over the study period. For the three surveys, mothers with one boy (girl) have 17 % (28 %) more likelihood of the next birth compared to the mothers with one girl and one boy. There is no significant difference in the likelihood of next birth between mothers with two boys, and that of with one girl and one boy. However, mothers with two girls are more likely to have shorter intervals compared with the mothers with a boy and a girl (HR: 1.089). Moreover, a significant interaction between family composition and survey year describes the change in the birth spacing behavior of mothers having different number of children relative to the balanced number of children over time. The interaction suggests that the mothers with one child (boy or girl) and two girl children still have shorter birth interval, though the likelihood is decreasing over the years.In all the models considered for analysing birth intervals, it has been found that the survival status of the index child has a significant effect on the likelihood of having the next child. Effect of child survival status on the timing of births is in the expected direction, and mothers with previous children alive has 60 % less likelihood of the next birth compared to the mothers who lost their previous child (Model II). A significant interaction between the survival status of the previous child and the survey year reveals that the effect of the survival of the previous child on birth spacing decreased over time.Examining the other covariates, it is clear that mothers from the middle and rich households are less likely to have shorter birth interval compared to that of from the poor households. Moreover, the pattern of birth intervals changes according to the place of residence and administrative division. Table τ are 0.170 (mother level) and 0.027 (community level) for the frailty models.Variance of frailty can help to select an appropriate model for fitting the birth interval data. Moreover, small frailty variance indicates no significant heterogeneity among the clusters, where a large variance implies greater heterogeneity. The estimated standard errors are found to be smaller for the models without frailty (i.e. Model I) compared to that of estimated from the frailty models (Models II and III). This is expected as the frailty models account for the extra variance associated with unobserved risk factors. From our analysis, estimates of the frailty variance are 0.411 (mother level) and 0.055 (community level) indicates that the lengths of birth intervals varies largely with mother compared to the community. In addition, estimates of Kendall’s Birth interval is a major determinant of fertility of a high populous country as well as an important indicator of socioeconomic development. According to BDHS (2011) policy brief, total fertility rate is declining over the time, and declination must be continued to achieve population stability in mid century with TFR 1.6 . The incFamily composition is a very important determinant of birth interval because the length of birth interval depends on whether a mother has a son or a daughter. Mothers who already have a son tends to have a longer birth interval compared to that of without a son. The estimated effect of family composition on the length of birth interval is similar to the findings of Mahmood et al. , Maitra Women’s involvement in education is one of the most beneficial measures to increase birth interval and reduce fertility , 19. ThiOn the other hand, women from wealthy families have significantly long birth interval due to education and lifestyle, which is compatible with the findings of Kamal and Khalid . Women fIn methodological point of view, parametric proportional hazards model without frailty underestimates the standard error of parameter estimators because the model does not consider the correlation among observations from the same cluster. In the current study, parametric frailty models are used to estimate the effects of covariates on birth interval after adjusting for the cluster variation in mother and community level. A significant variation among mothers and communities is found, which is consistent with the findings of Mahmood et al. . FurtherNote that the main objective of this paper is to identify potential determinants of birth intervals and examine how the impact of the important determinant changes over time after controlling the heterogeneity due to mother or community. In this paper, design weights have not been used in the analysis because objective of this paper is to estimate the effects of important determinants for birth interval, not to provide national level estimates of some indicators , 31.The current analysis provides evidence that socioeconomic and demographic variables do affect the distribution of birth spacing of women in Bangladesh. It could be suggested that a general social change is probably in place in Bangladesh, but we are not optimistic that this process of change has the tendency yet to induce people to opt for longer birth spacing and smaller family sizes due to smaller effect of some covariates over time. Specifically, this study emphasizes the need for gender composition and child mortality related studies in planning public health programs as per needs of the country. Further, female education also demonstrated an important protective role for increasing birth interval, so stronger strategies to ensure female education should be continued. In overall, interventions related to family planning should be stronger to keep birth interval longer and the fertility rate at the desired level. Moreover, there is a need of efficient policy for the promotion of longer birth spacing.


Postpartum depression and preterm birth (PTB) are major problems affecting women's health. PTB has been associated with increased risk of postpartum depressive symptoms (PDS). However, it is unclear if PTB in women with a prior history of PTB is associated with an incremental risk of PDS. This study aims to determine if PTB in women with a prior history of PTB is associated with an incremental risk of PDS. Data come from the 2009–2011 national Pregnancy Risk Assessment Monitoring System. Study sample included 55,681 multiparous women with singleton live births in the index delivery. Multiple logistic regression was used to examine the association between PTB and PDS. The risk of PDS was 55% higher in women with PTB in both deliveries  and 74% higher in women with PTB in the index delivery only , compared to women with term deliveries. Preterm birth is a risk factor for PDS. PTB in women with a prior history of PTB is not associated with an incremental risk of PDS. Routine screening for PDS should be conducted for all women and closer monitoring should be done for high risk women with PTB. Depression is a major medical problem affecting women's perinatal health. Approximately 10% to 15% of women experience postpartum depression after childbirth . In addiPoor birth outcomes such as preterm birth have been reported to increase the risk of postpartum depressive symptoms in women –7. O'briThe increased risk of postpartum depressive symptoms observed in women with preterm birth may be due to stress –12. MothPrevious preterm birth has been reported as one of the strongest determinants of a subsequent delivery of a preterm baby in women , 18. HowThis study utilized data from the 2009–2011 national Pregnancy Risk Assessment Monitoring System (PRAMS) and linked birth certificate data. PRAMS is a self-reported survey conducted by the Centers for Disease Control and Prevention (CDC) and state health departments. It is administered to a sample of recently delivered mothers within 2 to 6 months after delivery of a live infant and collects information on maternal behaviors, attitudes, and experiences before, during, and immediately after pregnancy. A complex multistage sampling design was utilized and data were weighted to account for sampling design, nonresponse, and noncoverage. Data were collected using mailed questionnaires and nonrespondents were contacted by telephone. Additionally, the PRAMS survey data were linked to birth certificate data to capture birth outcome and pregnancy history data. More details on the PRAMS methodology have been previously published  and are n = 1,728; 2.9%) and those who did not provide valid responses to questions on postpartum depressive symptoms in the current postpartum period  were excluded from the analysis. This yielded a total sample size of 55,681 women.The study sample for this analysis included multiparous women  with singleton live birth in the index delivery. Women with multifetal births  or whom multifetal birth status could not be ascertained and primiparous women were excluded from the study. Women with multifetal birth were excluded from the study because multifetal birth is known to increase the risk of postpartum depressive symptoms . This yiα = 0.82) based on an algorithm developed by Ohara et al. [The dependent variable, postpartum depressive symptoms, was measured using three items on the PRAMS questionnaire  successive preterm births (preterm births in both the penultimate and index deliveries), (2) preterm birth in penultimate delivery but no preterm birth in index delivery, (3) no preterm birth in penultimate delivery but preterm birth in index delivery, and (4) no preterm birth in both penultimate and index deliveries . Preterm birth in the penultimate delivery was measured using an item on the PRAMS questionnaire which asked mothers “Was the baby just before your new one born more than 3 weeks before his or her due date?” and preterm birth in the index delivery was determined using the clinical estimate of gestation at birth documented on the birth certificate. Further, preterm birth in the index delivery was categorized into very preterm (<32 weeks) and moderate-to-late (32–<37 weeks) preterm birth.2) and categorized based on the World Health Organization (WHO) classification into underweight (<18.50), normal weight (18.50–24.99), overweight (25.00–29.99), and obese (≥30.00). Stressful life events were assessed using a set of 13 questions that asked women to indicate whether they had experienced stressful events in the 12 months before giving birth  and were categorized based on the number of stressful experiences . Problems with breastfeeding was measured as an abrupt termination of breastfeeding in women who commenced breastfeeding of their babies. It was categorized into 3 categories—no breastfeeding problems, breastfeeding problems, and never breastfed. Previous live births (1 and ≥2) and marital status (married and not married) were obtained from the birth certificate.Covariates including sociodemographic factors, risky behaviors, and medical and obstetric factors were examined as potential confounders. Sociodemographic factors such as age , education (high school or less and college or higher), income , and prenatal insurance  were assessed. Race/ethnicity was categorized as non-Hispanic (NH) White, NH Black, Hispanic, and NH other. Non-Hispanic other consisted of other Asian, American Indian, Chinese, Japanese, Filipino, Hawaiian, other non-White, Alaska Native, and mixed race. Risky behaviors such as alcohol drinking and cigarette smoking were assessed using a woman's use in the last two years prior to the index pregnancy and categorized as dichotomous variables (yes or no). Medical morbidities  in the index pregnancy (yes or no) were also assessed. Pregnancy intention (intended or unintended) and intimate partner violence during the index pregnancy (yes or no) were measured as dichotomous variables. Prepregnancy body mass index (BMI) was calculated as weight in kilograms divided by height in meters squared . To determine if respondents who were excluded from the analysis due to missing data (4.3%) were different than those included in the analysis, we examined the distribution of preterm birth in the index delivery . Findings show that both groups were not significantly different . A significance level of α = 0.05 was used for all analyses. All results presented are based on analyses of weighted data.Statistical analysis was conducted using SAS-callable SUDAAN  utilizing appropriate weights to account for the complex survey design. Descriptive analyses were conducted to assess the distribution of participants' characteristics. Prevalence of postpartum depressive symptoms was calculated and factors associated with postpartum depressive symptoms were determined. Multiple logistic regression analysis was conducted to compute the risk ratios (RRs) and 95% confidence intervals (CIs) of the association between preterm birth and postpartum depressive symptoms using the average marginal prediction as described by Graubard and Korn . AverageSociodemographic characteristics of the study population are shown in The prevalence of postpartum depressive symptoms was higher in unmarried women, women who experienced stressful life events, women who were victims of intimate partner violence, those who never breastfed or had problems in breastfeeding, obese women, women who engaged in risky behaviors such as smoking cigarettes and drinking alcohol, and those whose pregnancies were unintended . The preThe present study shows that women with preterm birth in the index delivery only and those with preterm births in both the penultimate and index deliveries have an increased risk of experiencing postpartum depressive symptoms. These findings are consistent with those from previous studies that reported increased risk of postpartum depressive symptoms in women with preterm birth , 7–9. AlFurther, the study shows that women with preterm births in both the penultimate and index deliveries did not have greater risk of postpartum depressive symptoms than women with preterm birth in the index delivery only. A nonsignificant association between preterm birth and postpartum depressive symptoms in women with preterm birth in the penultimate delivery only, coupled with the lower risk of postpartum depressive symptoms observed in women with preterm births in both the penultimate and index deliveries than with women with preterm birth in the index delivery only, suggests that the risk of postpartum depressive symptoms may be driven by the experience of preterm birth in the index delivery. Furthermore, the risk of postpartum depressive symptoms in the index delivery was shown to only be significantly elevated in women with very preterm birth  and was not significantly elevated in women with moderate-to-late preterm birth (32–<37 weeks of gestation). This may suggest that even though preterm birth in the index delivery increases the risk of postpartum depressive symptoms, the risk may only be evident in women with very preterm birth. This may be due to greater level of stress in women with very preterm birth , as highOur findings were in contrast to the study hypothesis. The absence of a greater risk of postpartum depressive symptoms in women who had preterm births in both the penultimate and index deliveries over women who had preterm birth in the index delivery only may be explained by the acquisition of parenting skills and the development of self-efficacy in women with preterm birth in the penultimate delivery. Randomized controlled trials (RCTs) have demonstrated that interventions which addressed sources of maternal stress effectively reduced the level of stress in mothers , 35. MelIn keeping with the recommendations of the ACOG  and otheThis study provided important evidence regarding the relationship between preterm births in the penultimate and index deliveries and postpartum depressive symptoms. Despite the cross-sectional design of the study, temporal sequence of the exposure and outcome was established and this enabled us to calculate the risk of postpartum depressive symptoms utilizing robust statistical methods. Findings of this study should, however, be viewed in the light of some limitations. First, postpartum depressive symptoms were self-reported by women in PRAMS. There is the possibility that postpartum depressive symptoms may have been underreported due to social desirability or the stigma attached to postpartum depression. Second, we were unable to measure some important factors such as prior history of depression or depression in pregnancy, social support, and quality of mother's relationship with partner, due to nonascertainment of these factors in the PRAMS survey. Third, history of previous preterm birth was self-reported and not clinically measured. There is the possibility of recall bias in women who had their previous delivery several years back. Fourth, due to limitations of the data, we could not distinguish between spontaneous and iatrogenic preterm birth, and, lastly, study findings are not nationally generalizable as not all states in the US participate in PRAMS.This study showed that women with preterm births in the index delivery only and women with preterm births in both the penultimate and index deliveries have an increased risk of experiencing postpartum depressive symptoms. While preterm birth, particularly, very preterm birth, in the index delivery is associated with postpartum depressive symptoms, a prior history of preterm birth does not present an incremental risk in postpartum depressive symptoms. Routine screening for postpartum depressive symptoms should be conducted for all women using standardized, validated tools, and closer monitoring should be done for high risk women with preterm birth. Further, the birth of a preterm baby could serve as a teachable moment to educate women about preterm birth, appropriate maternal-infant interactions that can reduce the level of stress experienced by the mother, and identification of postpartum depressive symptoms. This will enable mothers of preterm babies to develop self-efficacy in the care of their babies, as well as recognize and seek immediate care for symptoms of postpartum depression.


We included 209 infants  who were born in university hospitals between 2014 and 2015 without apparent cardiac disease. We compared the ECG variability indices in 28 infants born before 37 gestational weeks  and 181 infants born at the average number of gestational weeks . There was a negative correlation between the QTVI and gestational weeks . QTVI values in preterm infants were larger than those in the controls . In conclusion, the QTVI is negatively correlated with gestational age. The QTVI can serve as an index of the maturity of the cardiac autonomic nervous system and myocardial depolarization.Reduced heart rate (HR) variability in preterm infants compared with full-term infants suggests that autonomic cardiac control is developmentally delayed. However, the association between developmental changes in myocardial repolarization and gestational age remains unknown. This study investigated the association between the myocardial repolarization lability index, namely the QT variability index (QTVI) = log Japan is currently the country with the lowest neonatal mortality rate in the world , 2. HoweHeart rate variability (HRV) reflects the complex interplay of sympathetic and parasympathetic innervation of the heart , 7. HRV Action potential duration, as reflected by the QT interval, is modulated by a previous cardiac cycle, and the QT interval varies according to the RR interval , 11. HowWe have previously reported developmental changes in the QTVI using body surface ECG in subjects from infants to school age . In thisWe screened 230 infants who were born at Fujita Health University Hospital between October 2014 and November 2015 and underwent 1-month outpatient examinations. In this study, 20 infants (1 preterm infant and 19 controls) were excluded because terminal T portion and P wave were overlapped due to extremely high heart rates (> 180 beats/min) and the end of T wave could not be accurately measured. One infant (control infants) with patent ductus arteriosus was also excluded. The remaining 209 subjects were enrolled. The subjects’ mean age was 32.9 ± 4.0 days, and their mean gestational age (GA) was 38.4 ± 1.6 weeks. The parents or guardians provided written informed consent.10 [(QTv/QTm2)/(HRv/HRm2)], Berger et al. [ECGs were recorded using a CM5 lead and a Biopac biological polygraph recording device model MP-150 . The recordings were performed between 2 and 3 pm in the afternoon before breastfeeding in the supine position while the subjects were quiet and awake. The RR intervals for the recordings of 60 heartbeats with stable baselines were automatically analyzed using the analytical software AcqKnowledge version 3.9 (Biopac Systems Inc.). Primary differentiation processing and absolute value processing were then performed using ECG waveforms. T-wave endpoints were determined, and RR and QT intervals for the same heart rates (HRs) were measured. The means and variances were calculated for the target HRs for each time point. We then calculated QTVI  usiBased on the recommendations of the American College of Obstetricians and Gynecologists , we defiχ2 test. Comparisons between the two groups of data were made using the unpaired Student’s t test or Wilcoxon ranked test as appropriate. Correlations between the variability indices and the number of gestational weeks were evaluated using linear regression analysis. A p level of < 0.05 was considered statistically significant.The statistical software package JMP  was used for the analyses. Data are presented as the mean ± standard deviation. The event frequencies were compared using the Table There were no significant differences in any of the ECG parameters between the two groups Table .r = − 0.46, p = 0.035) between the QTVI and GA (weeks) was observed . The QTVI was significantly higher in preterm infants than in controls (p = 0.023).Table In this study, we analyzed ECGs of 1-month-old infants and evaluated ventricular repolarization variability using the QTVI. We found that the QTVI was impaired in preterm infants and it was inversely related to GA.We have previously reported that the QTVI might indicate postnatal autonomic nerve development and ventricular repolarization maturity , 16. OurDysfunction of the autonomic nervous system is one of the causes of SIDS . VictimsThe QTVI is used for predicting cardiac events in adults with pathological hearts , 18. In The first limitation of this study is that all ECGs were recorded in the supine position while infants were awake and alert. Therefore, whether results were the same while subjects were asleep is unknown. Second, we did not have any information of fetal factors, placental/umbilical factors, and maternal factors, which might have affected the results. Third, we did not have any ECG data at birth. Therefore, we do not know whether QTVI is already impaired at birth in preterm infants and/or development is delayed after birth. Furthermore, because we only have ECG data of 1-month-old infants, we do not know whether there was a catch-up phenomenon . This is important because preterm infants may have, at least theoretically, an increased risk for SIDS until the time of catch-up because of immaturity of autonomic function. This possibility should be investigated in a future study.The QTVI in 1-month-old infants is impaired in those who are born preterm and is inversely related to GA. The QTVI could serve as an index of the maturity of cardiac autonomic nerves and myocardial repolarization in infants.