Maternal Metals Exposure and Infant Weight Trajectory: The Japan Environment and Children’s Study (JECS)

To our knowledge, the association of maternal exposure to metallic elements with weight trajectory pattern from the neonatal period has not been investigated.The goals of this study were to identify infant growth trajectories in weight in the first 3 y of life and to determine the associations of maternal blood levels of lead, cadmium, mercury, selenium, and manganese with growth trajectory.This longitudinal study, part of the Japan Environment and Children Study, enrolled 103,099 pregnant women at 15 Regional Centres across Japan between 2011 and 2014. Lead, cadmium, mercury, selenium, and manganese levels were measured in blood samples collected in the second (14-27 wk gestational age) or third trimester (We identified 5 trajectory patterns based on weight SD score: 4.74% of infants were classified in Group I, very small to small; 31.26% in Group II, moderately small; 21.91% in Group III, moderately small to moderately large; 28.06% in Group IV, moderately large to normal; and 14.03% in Group V, moderately large to large. On multinomial logistic regression, higher maternal lead and selenium levels tended to be associated with increased odds ratios (ORs) of poor weight SD score trajectories (Groups I and II), in comparison with Group III. Higher levels of mercury were associated with decreased ORs, whereas higher levels of manganese were associated with increased ORs of "moderately large" trajectories (Groups IV and V).Maternal lead, mercury, selenium, and manganese blood levels affect infant growth trajectory pattern in the first 3 y of life. https://doi.org/10.1289/EHP10321.