In this study, the authors related blood lead concentrations to Apgar scores, birth weight, gestational age, small-for-gestational age, and hypertension in pregnancy (HIP)/toxemia. Data and blood were collected 4 times during pregnancy from 705 women, aged 12-34 yr. Blood lead concentrations, measured by atomic absorption spectrophotometry, were related to reproductive outcomes, abstracted from medical records. Average blood lead concentrations were 1.2 microgram/dl (standard error = +/- 0.03). Maternal blood lead concentrations were related significantly to HIP/toxemia--before and after adjusting for age, calcium intake, and race/ethnicity (p < .03). Longitudinal regression analyses revealed that blood lead concentrations in women with HIP/toxemia changed by 0.02 microgram/dl for every 0.01 microgram/dl change in women without HIP/toxemia. Maternal blood lead concentration and its change were not significantly associated with other reproductive outcomes. Low levels of maternal blood lead concentrations were significantly associated with HIP/toxemia.