title: Environmental lead level and pregnancy-induced hypertension.
abstract: Previous studies have suggested that environmental lead exposure increases the risk of hypertension in the general population. In this article, the authors used the 1998 linked birth/infant death database of the United States to examine the association between environmental lead level and the occurrence of pregnancy-induced hypertension (PIH). Yearly summaries of environmental lead levels were abstracted from the US Environmental Protection Agency's air pollution databases, and linked with birth/infant death records by state codes. Generalized estimating equations (GEEs) were used to evaluate the odds ratios of PIH associated with environmental lead measured at ecological levels, with adjustment for maternal age, race, education level, marital status, parity, and adequacy of prenatal care measured at individual levels, stratified by maternal cigarette smoking. A total of 2,994,072 women pregnant in 1998 were included in this study. With the first quartile of lead level as the reference group, the odds ratio for PIH among all study subjects in the second quartile of seasonal average lead level at conception was 1.07 (95% CI: 1.05-1.08), and odds ratios in the third and fourth quartiles were 1.22 (95% CI: 1.20-1.25) and 1.16 (95% CI: 1.15-1.18), respectively. The odds ratios for the second, third, and fourth quartiles of seasonal average lead level at birth were 1.07 (95% CI: 1.05-1.09), 1.21 (95% CI: 1.19-1.23), and 1.15 (95% CI: 1.13-1.17), respectively. The risk of PIH increased by 4% per 0.05 microg/m3 increase in seasonal average lead level at conception and birth, in both smokers and nonsmokers. These results suggest that higher environmental lead levels increase the risk of PIH.
authors.affiliation: OMNI Research Group, Department of Obstetrics & Gynecology, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Xi-Kuan
authors.initials: XK
authors.lastname: Chen
authors.forename: Qiuying
authors.initials: Q
authors.lastname: Yang
authors.forename: Graeme
authors.initials: G
authors.lastname: Smith
authors.forename: Daniel
authors.initials: D
authors.lastname: Krewski
authors.forename: Mark
authors.initials: M
authors.lastname: Walker
authors.forename: Shi Wu
authors.initials: SW
authors.lastname: Wen
mesh_terms: D000328:Adult; D000367:Age Factors; D000393:Air Pollutants / Q000009:adverse effects*; D016208:Databases, Factual; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000453:epidemiology / Q000209:etiology*; D015994:Incidence; D007854:Lead / Q000009:adverse effects*; D008875:Middle Aged; D016017:Odds Ratio; D010298:Parity; D011247:Pregnancy; D011295:Prenatal Care; D014481:United States / Q000453:epidemiology
chemical_list: D000393:Air Pollutants; D007854:Lead