Prenatal care and infant lead exposure

Abstract

Objective: The objective of the study was to determine the relation between prenatal care of mothers and blood lead concentrations in their offspring in the first year of life. Methods: A retrospective survey was conducted of 200 predominantly black infants between the ages of 6 and 22 months (mean age, 13.4 months). The infants had been screened for the first time since birth at the Charleston County (South Carolina) Health Department. They resided in a neighborhood with the highest prevalence of lead poisoning in Charleston. Prenatal care use data were obtained after matching birth records with lead-screening records. Results: Seventy-three infants (37%) had blood lead levels 0.48 μmol/L (≥10 μg/dl) or higher. Adequacy of prenatal care, defined by the Modified Kessner Index, showed 11% with intensive care (26% of these with high lead levels), 39% with adequate care (35% high blood lead levels), 35% with intermediate care (40% with high blood lead levels), 13% with inadequate care (42% with high blood lead levels), and 2% with no prenatal care (25% with high blood lead levels). With the exception of the small group with no prenatal care ( n = 4), the proportion of infants with a high blood lead level was inversely proportional to the level of care. The logistic regression model that best fit the data included age at screen for lead and birth weight. Low birth weight babies (<2500 gm) were more likely to have a high blood lead level at primary screen than babies who were heavier at birth (odds ratio, 2.60; p = 0.04), and the older the baby at screening, the greater the likelihood of a high blood lead level (odds ratio, 1.23; p = 0.01). There was a trend for black infants to have a high blood lead level more often than white infants (odds ratio, 3.05; p = 0.06). Conclusions: Less than adequate use of prenatal care may reflect an increase in risk factors contributing to lead exposure in infancy. Low birth weight also was related to high blood lead levels. Further studies are required to differentiate among several hypotheses for this effect. Intrauterine lead exposure, which is known to reduce birth weight, may contribute to measured blood lead levels at first screen. Alternatively, low birth weight may increase lead absorption and retention in infancy or may increase risk of lead exposure. (J Pediatr 1997;130:123-7)