The effects of exposure to particulate matter and neighbourhood deprivation on gestational hypertension.

Gestational hypertension, pre-eclampsia and eclampsia are conditions that affect the health of both mothers and infants during and after pregnancy. Recent research indicates the importance of considering environmental, social and individual contributors to poor pregnancy outcomes. Our research examined particulate matter (PM) concentrations as one measure of environmental exposure and neighbourhood quality as one measure of the social environment. We used these measures, as well as maternal characteristics, to predict the risk of gestational hypertension (including pre-eclampsia and eclampsia). North Carolina Detailed Birth Record data for 2000-2003 were obtained and geocoded for all singleton births. Levels of PM(10) and PM(2.5) were determined using air quality data from the US Environmental Protection Agency. Information on a woman's residential neighbourhood was determined from 2000 Census data. Modified Poisson regression models clustered by tract were used to examine the associations between PM levels, neighbourhood deprivation and maternal characteristics with gestational hypertension. Analysis was restricted to women residing within 20 km of a PM monitor. Both PM(10) and PM(2.5) were associated with gestational hypertension; the risk ratios for an interquartile range (IQR) increase in exposure were 1.07 [95% confidence interval (CI) 1.04, 1.11] for PM(10) (IQR: 3.92 µg/m(3)) and 1.11 [95% CI 1.08, 1.15] for PM(2.5) (IQR: 2.24 µg/m(3)). Living in a neighbourhood with increased levels of deprivation was also associated with gestational hypertension. Any smoking during pregnancy, younger age and higher level of education were inversely associated with risk of gestational hypertension. Compared with non-Hispanic White women, non-Hispanic Black women were at higher risk of gestational hypertension, whereas Hispanic women were at lower risk. Increased levels of PM and neighbourhood deprivation, as well as certain individual characteristics, were associated with higher risk of gestational hypertension.