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Background Studies examining the effects of low-level gestational methylmercury exposure from fish consumption on infant neurobehavioral outcomes in the offspring are limited and inconclusive. Our objective was to examine the effects of low-level gestational exposure to methylmercury on neurobehavioral outcomes in early infancy. Methods We assessed neurobehavior of 344 infants at 5-weeks using the NICU Network Neurobehavioral Scale (NNNS). Gestational mercury exposure was measured as whole blood total mercury (WBTHg) in maternal and cord blood. We collected fish consumption information and estimated polyunsaturated fatty acid (PUFA) intake. We examined the association between gestational mercury exposure and NNNS scales using regression, adjusting for covariates. Results Geometric mean of maternal and cord WBTHg were 0.64 and 0.72 μg/L, respectively. Most mothers (84%) reported eating fish during pregnancy. Infants with higher prenatal mercury exposure showed increased asymmetric reflexes among girls (p = 0.04 for maternal WBTHg and p = 0.03 for cord WBTHg), less need for special handling during the assessment (p = 0.03 for cord WBTHg) and a trend of better attention (p = 0.054 for both maternal WBTHg and cord WBTHg). Similarly, infants born to mothers with higher fish consumption or estimated PUFA intake also had increased asymmetric reflexes and less need for special handling. In models simultaneously adjusted for WBTHg and fish consumption (or PUFA intake), the previously observed WBTHg effects were attenuated; and higher fish consumption (or PUFA intake) was significantly associated with less need for special handling. Conclusions In a cohort with low level mercury exposure and reporting low fish consumption, we found minimal evidence of mercury associated detrimental effects on neurobehavioral outcomes during early infancy. Higher prenatal mercury exposure was associated with more frequent asymmetric reflexes in girls. In contrast, infants with higher prenatal mercury exposure and those whose mothers consumed more fish had better attention and needed less special handling, which likely reflect the beneficial nutritional effects of fish consumption.

To examine the association of prenatal exposure to bisphenol A and select common phthalates with infant neurobehavior measured at 5 weeks.We compared the concentration of maternal urinary metabolites of bisphenol A and phthalates at two distinct time points in pregnancy (16w, 26w) with scores on the NICU Network Neurobehavioral Scale (NNNS) at 5 weeks of age in a cohort of 350 mother/infant pairs.Prenatal exposure to BPA was not significantly associated with neurobehavioral outcomes at 5 weeks. Significant associations between prenatal exposure to measured phthalates and infant neurobehavioral outcomes differed by type of phthalate and were only seen with exposure measured at 26 weeks. Higher total di-butyl phthalate (DBP) metabolites at 26w were associated with improved behavioral organization evidenced by decreased arousal (p=.04), increased self-regulation (p=.052), and decreased handling (p=.02). In males, higher total di-2-ethylhexyl phthalate (DEHP) metabolites at 26w were associated with more nonoptimal reflexes (p=.02).The association between prenatal phthalate exposure and infant neurobehavior differed by type of phthalate and was evident only with exposure measured at 26w. Prenatal exposure to DBP was associated with improved behavioral organization in 5-week-old infants. Prenatal exposure to DEHP was associated with nonoptimal reflexes in male infants. There was no evidence of an association between prenatal BPA exposure and infant neurobehavior.

Objective To examine the association between prenatal exposure to nicotine from tobacco smoke and infant neurobehavior using tobacco biomarkers and a sensitive and comprehensive measure of infant neurobehavior. Study design Participants were 318 infants (206 White, 95 Black, 17 Other) and their mothers. Prenatal tobacco smoke exposure was measured twice during pregnancy and once at delivery using maternal serum cotinine. Infant neurobehavior was assessed with the NICU Network Neurobehavioral Scale at approximately 5 weeks after birth. Results Prenatal tobacco smoke exposure was significantly associated with infant neurobehavior after controlling for important covariates, but the specific behaviors associated with exposure varied by race. In White infants, higher cotinine was associated with increased arousal ( p = .030) and excitability ( p = .034), and decreased self-regulation ( p = .010). In contrast, among Black infants, higher cotinine was associated with decreased arousal ( p = .001), excitability ( p = .021), and special handling required to complete the assessment ( p = .003), and increased self-regulation ( p = .021) and hypotonicity ( p = .016). In secondary analyses, we found racial differences in the effects of postnatal exposure to second hand smoke and low-level prenatal exposure. Conclusions Low-level prenatal tobacco smoke exposure is associated with infant neurobehavior at 5 weeks of age, but the specific effects differ by race. These effects may reflect racial differences in nicotine metabolism that are similar to differences reported in adult and child studies of tobacco.