Environmental contaminants and pregnancy outcomes.
OBJECTIVE
To review selected environmental, occupational, and other important risk factors for the following adverse pregnancy outcomes: low birth weight (LBW), intrauterine growth retardation (IUGR), and preterm delivery (PTD).


METHODS
The evidence is explored in greater detail for environmental tobacco smoke, drinking water disinfection byproducts, and organochlorine (DDT) and organophosphate pesticides, partly using a weight of evidence approach.


METHODS
Low birth weight and IUGR are surrogate measures of fetal growth that are determined at delivery. Low birth weight is defined as <2,500 grams, and occurs in about 7% of US births. Intrauterine growth retardation is commonly defined as birth weight less than the tenth percentile for gestational week, using a standard population. Preterm delivery is birth at <37 weeks gestational age, and occurs in approximately 12% of US births.


RESULTS
Numerous factors are associated with these endpoints that may be important to consider in studies of environmental exposures, such as young or old maternal age, race/ethnicity, multiple births, low socioeconomic status, inadequate prenatal care, low maternal weight gain, and infections and premature rupture of the membranes. Environmental contaminants found associated with increased risk of one or more of the endpoints include: tobacco smoke, carbon monoxide, air pollutants, heavy metals, pesticides, chlorination byproducts, and solvents.


CONCLUSIONS
Future research directions include measurement of exposure biomarkers during critical windows and consideration of genetic polymorphisms.
Windham
Gayle
G
Division of Environmental and Occupational Disease Control, California Department of Public Health, Richmond, California 94804, USA. gayle.windham@cdph.ca.gov
Fenster
Laura
L
D004785:Environmental Pollutants / Q000633:toxicity*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000139:chemically induced* / Q000453:epidemiology; D011256:Pregnancy Outcome; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced* / Q000453:epidemiology; D012307:Risk Factors
D004785:Environmental Pollutants