Maternal exposure to nickel in relation to preterm delivery.

Prior studies have suggested the reproductive effects of nickel; however, few epidemiological studies have investigated the associations of maternal exposure to nickel with preterm delivery. To investigate prenatal exposure to nickel as a risk factor for preterm delivery (< 37 weeks) in a large birth cohort. A total of 7291 pregnant women participated in the study were recruited between September 2012 and October 2014 in the longitudinal Healthy Baby Cohort (HBC) in Wuhan, China. Inductively Coupled Plasma Mass Spectrometry was employed to examine levels of nickel in urine from pregnant women collected before labor. The median urinary creatinine-corrected nickel was 5.05 creatinine μg/g with an inter-quartile range of 2.65-9.51 creatinine μg/g. We adjusted for potential confounders and found that each doubling in concentration of maternal urinary nickel was associated with an increase of 16% in adjusted odds ratios (ORs) for preterm delivery (95% CI: 1.08, 1.24). The associations were consistent for both spontaneous and iatrogenic preterm delivery. Our findings suggest that higher maternal urinary nickel concentrations were associated with an increased risk of preterm delivery.