Air pollution trims fetal growth

Pregnant women who breathe polluted air deliver babies that are slightly smaller than are those born to mothers in cleaner environments, new government research indicates.

Air pollution’s apparent influence on birth weight—typically little more than an ounce per infant—is probably too small to cause harm in most cases, says epidemiologist Jennifer D. Parker of the National Center for Health Statistics in Hyattsville, Md. Nevertheless, it may undermine health in infants at risk of problems for genetic or other reasons, she says.

Parker and her colleagues gathered data on about one-sixth of infants born in California in 2000, excluding those likely to have low birthweights because of premature birth or being born with a twin. The scientists also determined average air concentrations of two kinds of pollutants—carbon monoxide and particulates smaller than 2.5 micrometers across—near where the mothers lived during their pregnancies.

Mothers exposed to the highest fine-particulate concentrations gave birth to babies that weighed 35.3 grams less, or about 1 percent, on average than the babies of women living in communities with the cleanest air did.

The effects of particulate exposure seemed consistent from one trimester to the next, the researchers note in the January Pediatrics.

Carbon monoxide exposure, however, had no apparent influence on birth weight of exposed women’s babies.