Urinary vanadium concentration in relation to premature rupture of membranes: A birth cohort study

Heavy metal exposure has been indicated to be linked with reproductive and developmental toxicity. However, human studies on the association between heavy metal exposure and premature rupture of membranes (PROM) are limited. Thus, we aimed to evaluate the associations between urinary metal concentrations in pregnant women and the risk of PROM. The study was conducted among 7290 pregnant women from an ongoing cohort study in China. Levels of urinary metals were determined using an inductively coupled plasma-mass spectrometry and adjusted by creatinine concentration (μg/g creatinine). Adjusted odds ratios (OR) and 95% confidence intervals (CI) for PROM and preterm PROM were estimated using logistic regression models. Among 12 urinary metals detected, vanadium (V) have shown stable positive associations with PROM and preterm PROM. With one unit increase in natural logarithmically transformed urinary V concentration, adjusted OR of 1.57 (95% CI: 1.47, 1.66) for PROM was observed. Compared with the lowest tertile of urinary V, we also observed positive associations between V levels and PROM (for the medium tertile, adjusted OR = 1.66, 95% CI: 1.34, 2.05; for the highest tertile, adjusted OR = 3.75, 95% CI: 3.09, 4.54). In addition, higher adjusted ORs for preterm PROM were observed (for the highest tertile, adjusted OR = 8.14, 95% CI: 4.55, 14.55). Further stratified analysis suggested the associations were more pronounced among women delivering male infants than those with female infants. Our present epidemiological study indicated that pregnant women exposure to higher level of V might lead to an increased risk of PROM.