gestational diabetes mellitus ( gdm ) is defined as glucose intolerance 1st recognized during pregnancy with a prevalence of 2% to 14% in all pregnant women .
gdm is associated with maternal , fetal , and neonatal adverse outcomes such as cesarean delivery , preeclampsia , shoulder dystocia , macrosomia , neonatal hypoglycemia , and perinatal death .
although yet to be proven , screening and treating gdm may contribute to prevent adverse outcomes .
the most commonly used screening and diagnostic methods of gdm are flawed because they give relatively poor negative and positive predictive values .
the 2-step diagnosis method , the 1-hour 50-g glucose challenge test ( gct ) , and the 3-hour 100-g oral glucose tolerance test ( ogtt ) are currently used in the united states , and the single - step 2-hour 75-g ogtt is used in european countries . in korea , the 2-step diagnosis approach has been used predominantly as in the united states , but several hospitals have adopted new guidelines for the diagnosis of gdm . it is also necessary to change the current counseling and treatment approaches for gdm patients because perinatal outcomes tend to differ according to glucose levels .
patients with 50-g gct within 140 to 199  mg / dl had 2.5-fold increasing risk of large for gestational age ( lga ) and 2.9-fold increasing risk of macrosomia .
langer et al demonstrated that every 10  mg / dl increment in fasting blood glucose ( fbg ) resulted in 15% increase in adverse composite outcomes .
the purpose of this study is to evaluate the association between perinatal outcomes and 50-g gct values as well as fbg among gdm women .
a retrospective analysis of 3434 pregnant women who had 50-g gct was carried out between march 2001 and april 2013 at severance hospital , seoul , korea .
women with fetal anomalies , multiple gestations , overt diabetes mellitus ( dm ) , and hypertension were excluded from the study .
a total of 2631 pregnant women received the normal 50-g gct and 803 received the100-g ogtt because their 50-g gct value was greater than 140  mg / dl .
as a result , 307 patients were diagnosed with gdm ( gdm group ) and 496 showed false - positive result ( impaired glucose tolerance group ) .
a false - positive result was defined as showing positive in the 1-hour 50-g gct but negative in the 3-hour 100-g ogtt .
gdm was defined as showing 2 or more abnormal duration ( hours ) of 100-g ogtt values : fbg of 95  mg / dl or more ; 180  mg / dl or more for 1-hour ; 155  mg / dl or more for 2-hours ; and 140  mg / dl or more for 3-hours .
a total of 171 patients had normal fbg ( < 95  mg / dl ) and 136 patients had abnormal fbg ( 95  mg / dl ) ( fig .
the 1-hour 50-g gct result was also divided into 20-unit increments , and these subgroups were used to evaluate maternal and perinatal outcomes .
a total of 307 pregnant women ( the same number as gdm patients ) were randomly selected from the normal 1-hour 50-g gct group ( n = 2631 ) to be the control .
the risks of adverse maternal and perinatal outcomes for subgroups of the gdm group were then analyzed and compared against the control group .
maternal composite adverse outcomes included cesarean delivery and preeclampsia , while fetal composite adverse outcomes included lga , apgar score , intensive care unit admission , neonatal hypoglycemia , and hyperbilirubinemia .
preeclampsia was diagnosed according to the criteria of the acog practice bulletin : new onset of blood pressure of 140/90  mm  hg or more on 2 separate readings taken 6  hours apart after 20 gestational weeks ; and proteinuria of 300  mg/24  hours or more .
lga was defined as birth weight greater than the 90th percentile compared with gestational age .
neonatal hypoglycemia was defined as blood glucose level of less than 40  mg / dl , and hyperbilirubinemia was defined as bilirubin level of more than 5  mg / dl . for statistical processing , the chi - square test or fisher exact test
was used for categorical variables and the 2-sample t test or the wilcoxon rank sum test was used for continuous variables .
multiple logistic regression analysis was performed to estimate the odds ratios ( ors ) of adverse outcomes with adjustment for confounders .
cary , nc ) and statistical significance was considered for p - values  < 0.05 .
based on the results of the 50-g gct , the clinical characteristics and perinatal outcomes of the impaired glucose tolerance ( igt ) group and the gdm group ( table 1 ) were compared .
significant differences were observed between the 2 groups in terms of their maternal age , body mass index ( bmi ) before pregnancy and at delivery , and family history of dm . for perinatal outcomes ,
the gdm group showed higher incidence of cesarean delivery , macrosomia , lga , and neonatal hypoglycemia .
comparison of characteristics of igt and gdm groups . among gdm patients , maternal characteristics and perinatal outcomes
study findings show statistical significance in bmi before pregnancy and at delivery , rate of cesarean section , prevalence of gestational hypertension , gestational insulin therapy , and hba1c at diagnosis .
incidence of macrosomic newborn ( 3.5% for normal glycemic vs 22.1% hyperglycemic group , p  <  0.001 ) and lga newborn ( 10.5% for normal glycemic vs 36.0% hyperglycemic group , p  < 
0.001 ) was higher in the fasting hyperglycemic group , meeting the carpenter and coustan criteria .
moreover , the prevalence of neonatal hypoglycemia was 9.4% , and 15.4% in the normal glycemic and hyperglycemic groups , respectively ( p  <  0.001 ) . to compare perinatal outcomes between the 2 groups , the odds ratio was calculated after controlling for confounding factors ( table 3 ) .
the odds ratio for perinatal outcomes was 6.72 ( 95% ci : 2.5917.49 , p  <  0.001 ) with macrosomia , 3.75 ( 95% ci : 1.977.12 , p  <  0.001 ) with lga , and 1.65 ( 95% ci : 0.793.43 , p = 0.183 ) with neonatal hypoglycemia .
the maternal and perinatal outcomes of pregnant women with 50-g gct result of over 140  mg / dl were further stratified into 20-unit increments ( table 4 ) .
the findings showed significant differences in bmi before pregnancy and at delivery , incidence of gestational hypertension and gestational insulin therapy , hba1c at diagnosis of gdm , macrosomia , lga , and neonatal hypoglycemia .
the 50-g gct results were categorized and the perinatal outcomes were compared with 50-g gct normal group after adjusting for confounders ( table 5 ) . increased 50-g gct values in subgroups showed relevance with higher risk of perinatal outcomes .
the ors of macrosomia ( up to 20.31-fold ) , lga ( up to 6.15-fold ) , and neonatal hypoglycemia ( up to 84.00-fold ) were higher in subgroups with higher 50-g gct values . among gdm patients ,
the group with 50-g gct level of 140 to 159  mg / dl was found to be associated with macrosomia ( or : 4.31 , 95% ci : 1.4213.13 , p = 0.010 ) and neonatal hypoglycemia ( or : 17.27 , 95% ci : 2.03147.12 , p = 0.009 ) when compared against the normal group .
however , lga ( or : 0.84 , 95% ci : 0.401.73 , p = 0.628 ) did not show statistical significance .
the subgroup in the 160 to 179  mg / dl range showed significant or for macrosomia ( or : 5.95 , 95% ci : 1.9218.49 , p = 0.002 ) and neonatal hypoglycemia ( or : 53.72 , 95% ci : 6.78425.70 , p  <  0.001 ) .
lga ( or : 1.48 , 95% ci : 0.733.03 , p = 0.279 ) showed the tendency to increase but there was no statistical significance .
also , the subgroups in the 180 to 199  mg / dl and the 200  mg / dl ranges showed a strong association with all adverse perinatal outcomes .
therefore , risks of adverse perinatal outcomes increased as the values of 50-g gct results increased .
maternal characteristics and perinatal outcomes according to fasting glucose values in gdm patients . or of perinatal outcomes for fasting glucose level 95  mg / dl in gdm group . maternal and perinatal outcomes according to 50-g glucose challenge test in gdm patients . or of perinatal outcomes according to 50-g glucose challenge test values in gdm patients .
this study investigated the maternal and perinatal outcomes according to fbg and 50-g gct values in gdm pregnant women .
the risks of macrosomia , lga , and neonatal hypoglycemia increased with fasting hyperglycemia and higher 50-g gct values .
study findings also showed that the association between fasting hyperglycemia and adverse perinatal outcomes remain to be significant after adjustment for potential confounders .
previous studies have found that postprandial hyperglycemia was associated with excessive fetal growth in gdm patients requiring insulin therapy or pregestational diabetes patients .
other studies have indicated that meal - related glucose threshold measurement did not increase the risk of adverse fetal outcomes .
recently , other researches have demonstrated significant association between fasting and 1-hour 75-g ogtt glucose values with lga newborns among gdm women .
it has been reported that strict glucose control in this risk group may be necessary in order to avoid lga newborns .
it has been emphasized in many studies that fbg is an important factor in gdm screening as well as in predicting neonatal adverse outcomes .
gdm women with an isolated abnormal fbg were more likely to need hypoglycemic agents to obtain good glycemic control .
the significance and magnitude of this association was consistent with the results of this study . in the abnormal fbg group , 47.1% ( 64/136 ) of gdm patients needed gestational insulin therapy to control the blood glucose but in the normal fbg group ( p  <  0.001 ) , only 12.9% ( 22/171 ) of pregnant women who were diagnosed with gdm required insulin treatment .
the hapo studies have demonstrated the continuously increasing relationship between maternal blood glucose levels and adverse perinatal outcomes such as frequency of lga , neonatal hypoglycemia , cord blood serum c - peptide level above the 90th percentile , and primary cesarean section delivery .
however , these studies are based on the single step 75-g ogtt , and gdm was diagnosed using the international association of diabetes and pregnancy study groups ( iadpsg ) criteria . in the hapo studies , the outcomes were compared after categorizing fasting , 1-hour , and 2-hour glucose values . in contrast , this study is based on the 2-step diagnosis of gdm , and the outcomes of the 50-g gct values and the fbg of 100-g ogtt were compared against each other .
the outcomes found in this study give a more accurate picture of the situation in korea , where the 2-step diagnosis is predominantly used .
in addition , without adjusting for confounding factors , such as prepregnancy bmi and gestational weight gain , adverse outcome risks may have been overestimated in other earlier studies . however , in this study , the relation between maternal hyperglycemia and adverse perinatal outcomes were analyzed after adjusting for bmi before pregnancy and gestational weight gain , because bmi is also related to maternal and perinatal outcomes in gdm patients .
fbg has been used as the most important indicator for the diagnosis of dm in nonpregnant adults because it reflects impaired insulin secretion and resistance .
fbg values tend to stay constant throughout the entire period of pregnancy and this is also true for nonpregnant patients .
fbg values have less individual variation compared to other glucose values ; therefore , abnormal fbg level is a significant indicator in diagnosing gdm . at present , fbg is a good screening test for gdm with advantages such as simple procedure , reasonable cost , reproducibility , easy access , and wide acceptance .
recently , other studies have reported that abnormal fbg alone is capable of detecting 50% of pregnant women with gdm from a pool of women who had already been diagnosed with gdm with another screening method .
if combined with the 2-hour plasma glucose level , another 25% of pregnant women with gdm can be detected . in 2016 ,
park et al developed a more practical and efficient screening tool using fbg and prepregnancy bmi for predicting adverse outcomes of gdm .
this new screening tool focused on predicting the maternal and perinatal adverse outcomes of gdm patients .
the findings of this study show that bmi before pregnancy , bmi at delivery , hba1c value at diagnosis , and the application of gestational insulin therapy were much higher in the abnormal fbg group .
several studies have indicated that maternal prepregnancy bmi was associated with the risk of gdm .
sacks et al confirmed that maternal bmi had a powerful impact upon fetal birth weight . therefore , gdm patients with both higher bmi and abnormal fbg values can have potentially worse perinatal outcomes .
this study also showed that abnormal fbg values according to the carpenter and coustan criteria had significance association with higher incidence of lga , macrosomia , and neonatal hypoglycemia .
in addition , adverse perinatal outcomes according to different 50-g gct values among gdm patients were evaluated in this study .
the risks of macrosomia , lga , and neonatal hypoglycemia increased with increasing 50-g gct values .
several studies have examined the relationship of 50-g gct and perinatal outcomes . in 1987 , leikin et al reported that the false - positive gct group ( gct values of 135  mg / dl or more but normal ogtt values ) had higher incidence of macrosomia compared with the normal gct group ( 11.9% vs 6.4% , p = 0.009 ) .
recently , other retrospective cohort studies also showed that false - positive gct is an independent risk factor for adverse perinatal outcomes ( or : 5.96 , 95% ci : 1.310.3 ) .
the findings of this study suggest that the risks of the macrosomia ( up to 20.31-fold ) , lga ( up to 6.15-fold ) , and neonatal hypoglycemia ( up to 84.00-fold ) increased with higher 50-g gct values . more importantly ,
50-g gct values in the range of 140 to 159  mg / dl were not associated with lga compared to the normal 50-g gct group .
these results should be interpreted with caution since confidence intervals were very wide due to a limited number of cases in the 50-g gct normal group . in 2013 , figueroa et al evaluated the relationship between 50-g gct values and perinatal outcomes in mild gdm patients , and showed that gct values of 140  mg / dl or more were associated with an increase of composite perinatal outcomes , lga , and macrosomia .
however , there was no evaluation for the group with gct value of 200  mg / dl or more .
they only included mild gdm group with fasting glucose value less than 95  mg / dl .
the strength of this study is that a full spectrum of gdm patients were examined using the carpenter and coustan criteria , including the group with 50-g gct higher than 200  mg / dl .
therefore , it was possible to evaluate the continuous 50-g gct values in the lower or upper ranges .
this study also included normal and abnormal fasting glucose groups and the abnormal fbg group tended to have a greater risk for adverse perinatal outcomes .
a randomized clinical trial of a larger scale , using prospectively collected data from a well - characterized trial cohort , is ideal and necessary to validate the findings of this study .
all gdm women were treated to achieve the recommended value of their glycemic profiles and 28.0% ( 86/307 ) of the pregnant women with gdm needed insulin therapy . even without the influence of gdm management
in addition , long - term health complications such as childhood obesity , impaired insulin sensitivity , or type 2 diabetes mellitus were not considered for in this study . in conclusion ,
also , composite perinatal outcomes such as macrosomia , lga , and neonatal hypoglycemia are more frequent with increasing 50-g gct values .
therefore , more attention and care should be given during prenatal counseling , as well as more active therapeutic intervention taken when necessary with closer fetal monitoring , with the objective to reduce adverse perinatal outcomes in gdm patients with abnormal fbg or high 50-g gct values .
 abstractpregnancies complicated by gestational diabetes mellitus ( gdm ) are associated with increased risks of adverse maternal and fetal outcomes . 
 the risks of adverse pregnancy outcomes differ depending on the glucose values among gdm patients . for accurate and effective prenatal counseling , 
 it is necessary to understand the relationship between different maternal hyperglycemia values and the severity of adverse outcomes . with this objective 
 , this study reexamines the relationship between maternal hyperglycemia versus maternal and perinatal outcomes in gdm patients . for this study 
 , maternal hyperglycemia was diagnosed using the 2-step diagnostic approach.medical records of 3434 pregnant women , who received the 50-g glucose challenge test ( gct ) between march 2001 and april 2013 , were reviewed . as a result 
 , 307 patients were diagnosed with gdm , and they were divided into 2 groups according to their fasting glucose levels . 
 a total of 171 patients had normal fasting glucose level ( < 95  mg / dl ) , and 136 patients had abnormal fasting glucose level ( 95  mg / dl ) . 
 the 50-g gct results were subdivided by 20-unit increments ( 140159 , n = 123 ; 160179 , n = 84 ; 180199 , n = 50 ; and 200 , n = 50 ) , and the maternal and perinatal outcomes were compared against the normal 50-g gct group ( n = 307).maternal fasting blood glucose ( fbg ) level showed clear association with adverse perinatal outcomes . 
 the odds ratio ( or ) of macrosomia was 6.72 ( 95% ci : 2.5917.49 , p  <  0.001 ) between the 2 groups . 
 the ors of large for gestational age ( lga ) and neonatal hypoglycemia were 3.75 ( 95% ci : 1.977.12 , p  <  0.001 ) and 1.65 ( 95% ci : 0.793.43 , p   =  0.183 ) , respectively . also , the results of the 50-g gct for each category showed strong association with increased risks of adverse perinatal outcomes compared to the normal 50-g gct group . 
 the or of macrosomia ( up to 20.31-fold ) , lga ( up to 6.15-fold ) , and neonatal hypoglycemia ( up to 84.00-fold ) increased with increasing 50-g gct result . 