Objective: Associations between magnitude and timing of maternal pregnancy blood lead (Pb) levels (BLLs), birth weight, and total days of gestation were examined, as well as associations with related clinical diagnoses of low birth weight (LBW), preterm, and small-for-gestational-age (SGA) birth.Study Design: Among a sample of 262 mother-infant pairs studied retrospectively, one-way analysis of variance and regression statistics were used to measure the relationship between level of maternal pregnancy BLLs and birth outcomes while controlling for key maternal and newborn factors.
Results: Women with maximum pregnancy BLLs (max-PBLLs)X10 mg/dl tended to give birth earlier and their babies were at substantially increased risk for preterm and SGA birth. By holding other explanatory factors constant, each unit increase in max-PBLL above 10 mg/dl was found to be associated with a decrease of À0.3 in total days of gestation. Compared to women with lower levels, women with maxPBLLs X10 mg/dl were at a threefold increased risk for preterm birth (adjusted OR ¼ 3.2, 95% CI 1.2-7.4) and more than a fourfold increased risk for having an SGA infant (adjusted OR ¼ 4.2, 1.3-13.9). Second trimester maximum BLLs X10 mg/dl were associated with a steep decrease in total days of gestation (a decrease of À1.0 days per each unit increase above 10 mg/dl).Conclusions: These data provide evidence of the adverse effects of maternal pregnancy BLLs, particularly when levels are X10 mg/dl. Prenatal Pb exposure at these levels was associated with significant decreases in total days of gestation and an increased risk of preterm and SGA birth.
Background:
Lead can adversely affect child health across a wide range of exposure levels. We describe the distribution of blood lead levels (BLLs) in U.S. children ages 1–11 y by selected sociodemographic and housing characteristics over a 40-y period.
Methods:
Data from the National Health and Nutrition Examination Survey (NHANES) II (1976–1980), NHANES III (Phase 1: 1988–1991 and Phase II: 1991–1994), and Continuous NHANES (1999–2016) were used to describe the distribution of BLLs (in micrograms per deciliter;
) in U.S. children ages 1–11 y from 1976 to 2016. For all children with valid BLLs (
), geometric mean (GM) BLLs [95% confidence intervals (CI)] and estimated prevalence
(95% CI) were calculated overall and by selected characteristics, stratified by age group (1–5 y and 6–11 y).
Results:
The GM BLL in U.S. children ages 1–5 y declined from
(95% CI: 14.3, 16.1) in 1976–1980 to
(95% CI: 0.78, 0.88) in 2011–2016, representing a 94.5% decrease over time. For children ages 6–11 y, GM BLL declined from
(95% CI: 11.9, 13.4) in 1976–1980 to
(95% CI: 0.58, 0.63) in 2011–2016, representing a 95.3% decrease over time. Even so, for the most recent period (2011–2016), estimates indicate that approximately 385,775 children ages 1–11 y had BLLs greater than or equal to the CDC blood lead reference value of
. Higher GM BLLs were associated with non-Hispanic Black race/ethnicity, lower family income-to-poverty-ratio, and older housing age.
Discussion:
Overall, BLLs in U.S. children ages 1–11 y have decreased substantially over the past 40 y. Despite these notable declines in population exposures to lead over time, higher GM BLLs are consistently associated with risk factors such as race/ethnicity, poverty, and housing age that can be used to target blood lead screening efforts.
https://doi.org/10.1289/EHP7932
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