Associations between molybdenum exposure and ultrasound measures of fetal growth parameters: A pilot study.

Previous studies have suggested the association of molybdenum (Mo) exposure with some adverse outcomes. However, limited epidemiological studies have been performed to explore the association between maternal Mo exposure level and fetal growth. This study recruited 220 pregnant women during their second trimester. The mother's urinary Mo concentration was measured by inductively coupled plasma mass spectrometry (ICP-MS). The fetal biometric parameters, including head circumference (HC), biparietal diameter (BPD), femur diaphysis length (FL), and abdominal circumference (AC) were assessed by prenatal ultrasound. Estimated fetal weight (EFW) was evaluated using the formula of Hadlock. Multivariable linear regression models were applied to estimate the relationships between Mo level and fetal biometric parameters, and potential confounders were adjusted. A one-unit increment in natural-logarithm transformed urinary Mo level was significantly associated with reductions in fetal AC of -0.34 cm (95%CI: -0.63, -0.04), and was negatively related to EFW (β = -18.2, 95%CI: -40.5, 4.2). Furthermore, when participants were stratified by copper (Cu) level, the results showed that the magnitude of negative association between Mo and AC (β = -0.55, 95%CI: -1.13, 0.04) was greater in pregnant women with Cu level below median value, comparing with those with Cu level above median value (β = -0.08, 95%CI: -0.57, 0.42), and a similar pattern was found for EFW, although the interaction between Mo and Cu was not significant. Our data suggested an inverse association of maternal urinary Mo level with fetal AC and EFW during the second trimester of pregnancy. These associations might be stronger in pregnant women with relatively lower Cu levels.