BackgroundDisturbances in the homeostasis of essential trace elements (ETEs) may interfere with embryonic organogenesis. However, the effect of ETEs on the development of orofacial clefts (OFCs) remains unclear. ObjectivesThis study examined associations between concentrations of iron (Fe), zinc (Zn), selenium (Se), cuprum (Cu), cobalt (Co), and molybdenum (Mo) in maternal serum and risk for OFCs in offspring. MethodsA total of 130 cases of OFCs and 260 nonmalformed controls were included in this study. Concentrations of Fe, Zn, Se, Cu, Co, and Mo in maternal serum were detected by inductively coupled plasma mass spectrometry. We examined associations between levels of the six ETEs in maternal serum and risk for OFCs for each element separately using multilevel mixed-effects logistic regression and for all elements collectively using Bayesian kernel machine regression (BKMR). ResultsHigher concentrations of Mo and Co in maternal serum were associated with a decreased risk for OFCs in a dose-dependent manner, with odds ratios and 95% confidence intervals of 0.37 (0.20–0.66) for the second tertile of Mo, 0.28 (0.15–0.54) for the third tertile of Mo, 0.54 (0.29–1.00) for the second tertile of Co, and 0.47 (0.25–0.87) for the third tertile of Co, with the lowest tertile as the referent. When all six ETEs were considered together, increased levels of ETEs were associated with a decreased risk for OFCs. In addition, Mo showed a protective effect against risk for OFCs when the other ETEs were fixed at their 25th, 50th, or 75th percentile, whereas the protective effect of Co turned to a null effect in the BKMR model. No association was observed between levels of Fe, Zn, Se, or Cu and risk for OFCs in either statistical model. ConclusionElevated concentrations of Mo in maternal serum were associated with a reduced risk for OFCs.