Chronic hepatitis B infection and risk of preterm labor: a meta-analysis of observational studies.

Many epidemiological studies have found a positive association between chronic hepatitis B virus (CHB) infection and the risk of preterm labor, but the magnitude of this association varies and independent studies have reported conflicting findings. We performed a meta-analysis to ascertain the relationship between CHB infection and preterm labor. The PubMed and Embase databases were searched up to May 1st, 2014, for relevant observational studies on an association between CHB infection and the risk of preterm labor. Data were extracted and analyzed independently by two authors. The meta-analysis was performed using Stata version 10.0 software. Six observational case-control studies and 4 cohort studies, involving 6781 women with preterm labor, were identified. Based on a random-effects meta-analysis, no association between CHB infection and preterm labor was identified (odds ratio=1.12, 95% confidence interval CI, 0.94-1.33). Our meta-analysis suggested that CHB infection is not associated with an increased risk of preterm labor.