Objectives Maternal exposure to lead (Pb) has been suggested to correlate with adverse birth outcomes, but evidence supporting an association between Pb exposure and premature rupture of membranes (PROM) is limited. The aim of our study was to investigate whether maternal Pb exposure was associated with PROM and preterm PROM.
Design Cross-sectional cohort study.
Study population The present study involved 7290 pregnant women from the Healthy Baby Cohort in Wuhan, China, during 2012–2014.
Main outcome measures PROM was defined as spontaneous rupture of amniotic membranes before the onset of labour and was determined with a pH ≥6.5 for vaginal fluid. Maternal urinary Pb level was adjusted by creatinine concentration, and its relationship with PROM was analysed by logistic regression.
Results The IQR of maternal urinary Pb concentrations of the study population was 2.30–5.64 µg/g creatinine with a median of 3.44 µg/g creatinine. Increased risk of PROM was significantly associated with elevated levels of Pb in maternal urine (adjusted OR 1.23, 95% CI 1.0 to 1.47 for the medium tertile; adjusted OR 1.51, 95% CI 1.27 to 1.80 for the highest tertile). The risk of preterm PROM associated with Pb levels was significantly higher when compared with the lowest tertile (adjusted OR 1.24, 95% CI 0.80 to 1.92 for the medium tertile; adjusted OR 1.73, 95% CI 1.15 to 2.60 for the highest tertile). In addition, the relationship between Pb and PROM was more pronounced among primiparous women than multiparous women (p for interaction <0.01).
Conclusions Our study found that higher levels of maternal Pb exposure was associated with increased risk of PROM, indicating that exposure to Pb during pregnancy may be an important risk factor for PROM.
- lead exposure
- premature rupture of membranes
- maternal urine
- birth cohort
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SH and WX contributed equally.
Contributors SH carried out the statistical analyses and drafted the manuscript. WX and XS assisted in the statistical analyses, critically reviewed and revised the manuscript. LQ, BZ, TC and SX contributed to the study design and developed the initial protocol. YL contributed to the study design, critically reviewed and revised the manuscript. All authors read and approved the final manuscript.
Funding This work was supported by the National Natural Science Foundation of China (91743103, 91643207, 21437002, 81372959, and 81402649), the National Key Research and Development Plan (2016YFC0206700, 2016YFC0206203), and the Fundamental Research Funds for the Central Universities HUST (2016YXZD043, 2015ZDTD047).
Competing interests None declared.
Patient consent Not required.
Ethics approval The ethical committees of Tongji Medical College, Huazhong University of Science and Technology and the study hospital approved the study protocol.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Extra data are available by emailing to the corresponding author at firstname.lastname@example.org.
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