The relationship between prenatal exposure to lead and congenital anomalies
H. L. Needleman, M. Rabinowitz, A. Leviton, S. Linn and S. Schoenbaum
We obtained umbilical cord blood from 5,183 consecutive deliveries of at
least 20 weeks' gestation and analyzed them for lead concentration. Those
demographic and socioeconomic variables, including lead, which were shown
on univariate analysis to be associated with increased risk for congenital
anomalies were evaluated and controlled by entering them into a stepwise
logistic-regression model with malformation as the outcome. Coffee,
alcohol, tobacco, and marijuana use, which were associated with lead level,
but not risk of malformation, were also controlled. The model was reduced
in steps by eliminating the variables with the highest P value, until the
most parsimonious model was created. The relative risk for anomalies
associated with lead was then calculated while holding other covariates
constant. Lead was found to be associated, in a dose-related fashion, with
an increased risk for minor anomalies.
