BLOOD LEAD LEVEL, BY YEAR AND SEASON, AMONG POOR PREGNANT-WOMEN

The authors conducted a longitudinal study of poor pregnant women and their infants to examine the determinants of maternal and infant lead levels. To accurately depict these determinants, one must account for secular and seasonal variations in these levels. The women's lead leve ls declined over the 5-y period of study by approximately 20%/y, depen ding on when in the course of pregnancy measurements were made. After correction for secular trend, we found a periodic effect that differed from that typically seen in children (i.e., peak occurs in summer). I n this study, lead levels in these women peaked during December-March. If the effects of lead are greatest in the youngest conceptus, early pregnancies that occur in the December-March period pose the largest p renatal risk.