Association between blood manganese level during pregnancy and birth size: The Japan environment and children's study (JECS)

Highlights: • Maternal blood Mn levels during pregnancy may correlate with birth size. • A nonlinear relationship of log Mn level with male birth weight was observed. • Male infants in the lowest quartile of Mn level faced an increased risk of SGA. • Males in the highest quartile of Mn level in 3rd trimester had a high risk of SGA. • A low Mn level correlated with small head circumference in all infants. -- Abstract: Manganese (Mn) is both an essential element and a potential toxicant. Although a few studies have suggested a nonlinear relationship between the maternal whole blood Mn level at delivery and infant birth weight, little is known about the effects of Mn levels during pregnancy on fetal growth, particularly with regard to sex-specific differences.