Adverse birth outcomes consist of a number of health effects involving pregnancy and the fetus or newborn infant (EPA, 2013m). Adverse birth outcomes include:
- Preterm birth: live birth before 37 completed weeks of pregnancy
- Normal term pregnancies last between 37 and 41 weeks, allowing more complete development of an infant's organs and system
- Small for gestational age (SGA): babies smaller than normal for their gestational age (roughly equivalent to the length of the pregnancy)
- Typically due to a restriction in growth in the uterus
- Low birthweight: infants who weigh less than 2,500 grams (about 5 ½ pounds) at birth
- May be caused by preterm birth, the infant being SGA, or a combination of both
- Fetal or infant death: death of the fetus in utero, or of the infant after birth but before one year of age
- Birth defect: structural changes in one or more parts of the infant's body that are present at birth
Infants with one or more adverse birth outcome are at greater risk for mortality and a variety of health and developmental problems, which can also have a significant emotional and economic impact on the infant's family (EPA, 2013m). The death rate for low birth weight infants is approximately 25 times higher than the death rate for normal weight babies. Similarly, the death rate for preterm babies (pregnancy lasting 34 - 36 weeks) is three times higher than the death rate for infants born after a normal length pregnancy. Babies with adverse birth outcomes are also more likely to experience complications like respiratory, immunologic, nervous system, behavioral, and developmental problems. The risk for these issues increases as birthweight and size for gestational age decrease (EPA, 2013m).
Adverse Birth Outcomes and Air Pollution | Top
While maternal characteristics and behaviors play an extremely important role in adverse birth outcomes, other factors like exposure to environmental pollutants may also contribute. Maternal exposure to lead has been shown to cause decreased fetal growth, and there is some evidence suggesting an association with preterm birth (NTP, 2012). A number of studies have identified potential links between adverse birth outcomes and exposure to elevated levels of air pollutants like particulate matter, sulfur dioxide, nitrogen dioxide, and carbon monoxide (EPA, 2013m; Shah et al., 2011). A recent study found that maternal exposure to ozone during the second and third trimesters and carbon monoxide exposure during the first trimester was associated with reduced birth weight (Salam et al., 2005).
Data and Indicators | Top
The Utah Environmental Public Health Tracking Program (EPHT) has created a number of indicators exploring data on adverse birth outcomes in Utah. An indicator is a fact or trend that indicates the level or condition of something. Well known indicators include gross national product, unemployment rates, and presidential approval ratings. In a public health context, indicators show trends like cancer rates, drinking water contamination levels, and blood lead levels in children. Visit the EPHT frequently asked questions page for more information.