Variation in blood lead and hematocrit levels during pregnancy in a socioeconomically disadvantaged population

Lead is a long-recognized human toxicant that crosses the placenta, Fetal s ensitivity to environmental agents can vary with stage of development; ther efore, how maternal blood lead levels change during pregnancy and how fetal exposure is influenced provide useful knowledge. In this study, the author s describe longitudinal changes in blood lead levels during the course of p regnancy in a sample of socioeconomically disadvantaged pregnant women. The women were recruited early in pregnancy when they sought care at one of tw o obstetrics clinics in Albany, New York. Maternal blood lead levels change d between the 1st and 2nd trimesters, from 1.99 mu g/dl to 1.69 mu g/dl (he matocrit corrected, 1.70-1.62); between the 2nd and 3rd trimester from 1.78 mu g/dl to 1.86 mu g/dl (hematoctit corrected, 1.65-1.72); and between 3rd trimester and delivery from 1.80 mu g/dl to 2.17 mu g/dl (hematocrit corre cted, 7.70-1.86). These changes were statistically significant and were cor rected for secular trends. The rate of change per day in lead levels averag ed -36.6% from trimester 1 to trimester 2, 18.3% from trimester 2 to trimes ter 3, and -40.8% from trimester 3 to delivery. The patterns in our study w ere consistent with the patterns reported in a few other longitudinal studi es of change in lead level during pregnancy. Findings reveal significant as sociations between maternal blood lead levels and both hematocrit and trime ster of pregnancy. Clinicians who interpret test results should take into a ccount the dynamics of these variables when determining appropriate care fo r both mother and neonate.