Associations between multiple serum metal exposures and low birth weight infants in Chinese pregnant women: A nested case-control study.

To investigate the associations between prenatal exposure to single metal and multiple metals and the risk of low birth weight (LBW), we conducted a nested case-control study of 246 LBW and 406 NBW mother-infant pairs based on a prospective birth cohort study. 22 serum metals were detected by inductively coupled plasma quadruple mass spectrometry (ICP-MS). Categorical analyses showed serum Co and Ti were associated with LBW (Co: 3rd vs 4th. quartile: OR = 1.83, 95%CI: 1.14-2.92, P = 0.043; Ti: 2nd vs. 4th quartile: OR = 0.51, 95% CI: 0.32-0.81, P trend = 0.051), especially gestational age >13 weeks (Co: 3rd vs. 4th quartile: OR = 1.94, 95% CI: 1.13 - 3.32, Ptrend = 0.043; Ti: 2nd vs. 4th quartile: OR = 0.50, 95% CI: 0.30 - 0.84, P trend= 0.073). Cubic spline analyses showed serum Co and serum Ti had non-linearity associations with LBW (Co: P for overall = 0.048, P-nonlinearity = 0.014; Ti: P for overall = 0.015, P- nonlinearity = 0.008). In multi-metal compound exposure model, 15 metals selected by elastic net model were significantly associated with the increased risk of LBW and OR (95%CI) was 5.14 (2.81-9.40). Our study suggested that lower level serum Co was positively associated with LBW and lower level serum Ti was negatively associated with LBW, especially gestational age >13 weeks, and both of them had non-linearity dose-relationships with LBW. And multi-metal compound model was significantly associated with LBW compared with single metal model.