Lead exposure at each stage of pregnancy and neurobehavioral development of neonates

Abstract

Purpose: Our pilot studies showed that there was a significant relationship between blood lead levels of women at the first trimester and scores of neonatal behavioral neurological assessment (NBNA). This study went further (1) to determine particular neurotoxicity during a specific trimester, (2) to analyze "safe" levels of Pb in neonates, and (3) to identify influencing factors for prenatal Pb exposure.

Method: A total of 415 mothers with newborn located Shenzhen, Guangdong, China participated in the study: 219 in the high lead group [blood lead levels (BLLs) at first trimester≥4.89μg/dl] and 196 in the low lead group [BLLs≤1.96μg/dl]. The maternal BLLs at each stage of pregnancy and delivery were measured by atomic absorption spectrophotometry, equipped with a graphite furnace. The developmental functioning of newborns was assessed with NBNA in 3 days. The children's birth outcome and the rest of information was obtained from their medical records or a comprehensive questionnaire from their parents, which contained demographic characteristics, lifestyle, IQ, occupation and influencing factors for lead exposure during and before first trimester, etc.

Results: Of 415 newborns, 332 (80.00%) had complete data collection for all variables at four-stage follow-up. The maternal mean BLL at first trimester for 332 newborns was 3.98±1.15μg/dl (0.38-15.86μg/dl) and the geometric mean (GM) was 3.63±0.35μg/dl (95%CI: 2.98-4.32μg/dl). In total, about 4.82% of newborns had maternal BLLs>10μg/dl. Significant inverse associations have been found between the maternal BLLs at the first trimester and the NBNA scores (P<0.05). Drinking milk and supplements of Ca, Fe, or Zn are protective factors of high BLLs (OR=0.363, P<0.05).

Conclusion: Our study demonstrate that fetal lead exposure as low as 5μg/dl has an adverse effect on neurodevelopment, most expressed during the first trimester and best arrested by measuring maternal BLLs. The collective evidence indicates that screening and intervention after the first trimester may be too late to prevent the fetal neurotoxic effects.

Keywords: Lead exposure; Neurobehavioral development; Newborns.