<unk>  is either caused by preterm birth (that is, a low gestational age at birth, commonly defined as younger than 37 weeks of gestation) or the infant being small for gestational age (that is, a slow prenatal growth rate), or a combination of both. In general, risk factors in the mother that may contribute to<unk>  include young ages, multiple pregnancies, previous<unk>  infants, poor nutrition, heart disease or hypertension, untreated celiac disease, substance use disorder, excessive alcohol use, and insufficient prenatal care. It can also be caused by prelabor rupture of membranes. Environmental risk factors include smoking, lead exposure, and other types of air pollutions. Preterm birth The mechanism of preterm birth is heterogeneous and poorly understood. It may be tied to one or more of the following processes: premature fetal endocrine activation, intrauterine inflammation, over-distension of the uterus, and endometrial bleeding. A prominent risk factor for preterm birth is prior history of preterm delivery. However, there is no reliable protocol for screening and prevention of preterm birth. Small for gestational age Infants born small for gestational age may be constitutionally small, with no associated pathologic process. Others have intrauterine growth restriction (IUGR) due to any of various pathologic processes. Babies with chromosomal abnormalities or other congenital anomalies may manifest IUGR as part of their syndrome. Problems with the placenta can prevent it from providing adequate oxygen and nutrients to the fetus, resulting in growth restriction. Infections during pregnancy that affect the fetus, such as rubella, cytomegalovirus, toxoplasmosis, and syphilis, may also affect the baby's<unk> . Environmental factors Maternal tobacco smoking doubles risk of<unk>  for the infant. More recently, passive maternal smoking has been examined for possible effects on birth<unk> , and has been shown to increase risk of<unk>  by 16%. Air pollutants The combustion products of solid fuel in developing countries can cause many adverse health issues in people. Because a majority of pregnant women in developing countries, where rate of<unk>  is high, are heavily exposed to indoor air pollution, increased relative risk translates into substantial population attributable risk of 21% of<unk> . Particulate matter, a component of ambient air pollution, is associated with increased risk of<unk> . Because particulate matter is composed of extremely small particles, even nonvisible levels can be inhaled and present harm to the fetus. Particulate matter exposure can cause inflammation, oxidative stress, endocrine disruption, and impaired oxygen transport access to the placenta, all of which are mechanisms for<unk> ening the risk of<unk> . To reduce exposure to particulate matter, pregnant women can monitor the EPA’s Air Quality Index and take personal precautionary measures such as reducing outdoor activity on low quality days, avoiding high-traffic roads/intersections, and/or wearing personal protective equipment (i.e., facial mask of industrial design). Indoor exposure to particulate matter can also be reduced through adequate ventilation, as well as use of clean heating and cooking methods. A correlation between maternal exposure to carbon monoxide (CO) and<unk>  has been reported that the effect on birth<unk>  of increased ambient CO was as large as the effect of the mother smoking a pack of cigarettes per day during pregnancy. It has been revealed that adverse reproductive effects (e.g., risk for<unk>  were correlated with maternal exposure to CO emissions in Eastern Europe and North America. Mercury is a known toxic heavy metal that can harm fetal growth and health, and there has been evidence showing that exposure to mercury (via consumption of large oily fish) during pregnancy may be related to higher risks of<unk>  in the offspring. Other exposures Elevated blood lead levels in pregnant women, even those well below the US Centers for Disease Control and Prevention's 10 ug/dL "level of concern", can cause miscarriage, premature birth, and<unk>  in the offspring. Exposure of pregnant women to airplane noise was found to be associated with<unk>  via adverse effects on fetal growth. Prevalence of<unk>  in Japan is associated with radiation doses from the Fukushima accidents of March 2011. Periodontal health<unk> , preterm birth and preeclampsia have been associated with maternal periodontal disease, though the strength of the observed associations is inconsistent and varies according to the population studied, the means of periodontal assessment and the periodontal disease classification employed. The risk of<unk>  can be reduced with treatment of the periodontal disease. This therapy is safe during pregnancy and reduces the inflammatory burden, thus decreasing risk for preterm birth and<unk> .
Low birth weight
Low Birth Weight
Preterm birth
Breech birth
Gestational age
Stillbirth
Multiple birth
Small for gestational age