Increases in hypertension and blood pressure during pregnancy with increased bone lead levels

Prior studies have revealed associations of current lead exposure (blood lead) and past lead exposure (bone lead) with risks of hypertension and elevated blood pressure. The authors examined the effects of blood and bone lead on hypertension and elevated blood pressure in the third trimester and postpartum among 1,006 women enrolled in Los Angeles prenatal care clinics between 1995 and 2001. The authors measured bone lead concentration by K-shell x-ray fluorescence in the tibia (mean = 8.0 micro g/g (standard deviation (SD) 11.4)) and calcaneus (heel) (mean = 10.7 micro g/g (SD 11.9)). Geometric mean prenatal and postnatal blood lead levels were 1.9 micro g/dl (geometric SD +3.6/-1.0) and 2.3 micro g/dl (geometric SD +4.3/-1.2), respectively. For each 10- micro g/g increase in calcaneus bone lead level, the odds ratio for third-trimester hypertension (systolic blood pressure > or =140 mmHg or diastolic blood pressure > or =90 mmHg) was 1.86 (95% confidence interval (CI): 1.04, 3.32). In normotensive subjects, each 10- micro g/g increase in calcaneus bone lead level was associated with a 0.70-mmHg (95% CI: 0.04, 1.36) increase in third-trimester systolic blood pressure and a 0.54-mmHg (95% CI: 0.01, 1.08) increase in diastolic blood pressure. Tibia bone lead concentration was not related to hypertension or elevated blood pressure either in the third trimester or postpartum, nor was calcaneus bone lead related to postpartum hypertension or elevated blood pressure. Past lead exposure influences hypertension and elevated blood pressure during pregnancy. Controlling blood pressure may require reduction of lead exposure long before pregnancy.