Prenatal and Early Childhood Exposure to Lead and Repeated Measures of Metabolic Syndrome Risk Indicators From Childhood to Preadolescence

Abstract

Background: Exposure to lead (Pb) during the early life stages has been associated with the development of metabolic syndrome (MetS). Longitudinal studies of Pb exposure in critical developmental windows in children are limited.Methods: Our study included 601 mother–child dyads from the PROGRESS (Programming Research in Obesity, Growth, Environment and Social Stressors) birth cohort. Blood lead levels (BLLs) were assessed during the second and third gestational trimesters, in cord blood at delivery, and at ages 1, 2, and 4 years. Bone lead levels in the patella and tibia were assessed at 1 month postpartum and evaluated in separate models. To account for cumulative exposure (prenatal, postnatal, and cumulative), we dichotomized the BLLs at each stage visit and determined the following: “higher” if a BLL was at least once above the median (HPb) and “lower” if all BLLs were below the median (LPb). We analyzed fasting glucose, HbA1c, triglycerides (TGs), total cholesterol (TC), high-density lipoprotein cholesterol (cHDL), low-density lipoprotein cholesterol (cLDL), body mass index, waist circumference (WC), body fat percentage, and systolic (SBP) and diastolic blood pressure (DBP) at two study visits between 6 and 12 years of age and created cutoff points based on the clinical guidelines for each indicator. Mixed effects models were used to analyze each outcome longitudinally for each BLL score, adjusting for child's sex, size for gestational age, child's age, maternal parity, mother's age, and socioeconomic status.Results: We observed associations for HPb exposure and TC in all stages (OR = 0.53, 95%CI = 0.32–0.86) and postnatally (OR = 0.59, 95%CI = 0.36–0.94) and for prenatal HPb and TGs (OR = 0.65, 95%CI = 0.44–0.95). HPb at all stages was associated with WC (OR = 0.27, 95%CI = 0.08–0.86), BMI (OR = 0.33, 95%CI = 0.11–0.99), SBP (OR = 0.53, 95%CI = 0.32–0.85), and DBP (OR = 0.57, 95%CI = 0.34–0.95). Pb levels in the patella were associated with cHDL (OR = 1.03, 95%CI = 1.00–1.07) and those in the tibia with TGs (OR = 0.95, 95%CI = 0.91–0.99).Conclusion: Early life exposure to Pb may alter early indicators of MetS. A follow-up of these children will allow for more definition on the impact of longer-term exposures.