Maternal age and educational level modify the association between chronic hepatitis B infection and preterm labor

Few studies have investigated whether maternal age and education level modify the association of chronic hepatitis B virus (HBV) infection with preterm labor. We hypothesized that the association of HBV infection with preterm labor is modified by maternal age and education level.

A retrospective cohort study was conducted on the HBsAg-positive and HBsAg-negative pregnant women delivered from June 2012 to August 2017 at Wuhan Medical Care Center for Women and Children, Wuhan, China. A multivariate regression model was used in this study.

This study included 2050 HBsAg-positive pregnant women and 2050 HBsAg negative women. In the stratified analyses, positive HBsAg status was associated with the increased risk of preterm labor in women aged < 30 years, having low educational level, with an odds ratio of 1.65(95% CI 1.07–2.54) and 2.59(95% CI 1.41–4.76), respectively. Breslow-Day test showed that there existed significant differences in the ORs for HBsAg carriage across each stratum of maternal age (p = 0.023), educational level (p = 0.002). After adjusting other co-variables, we observed maternal HBV infection (OR 1.60, 95% CI 1.03–2.49) was still associated with risk of preterm labor in pregnancy women with age < 30. Similarly, the significant association of HBV infection (OR 2.49, 95% CI 1.34–4.63) with preterm labor remained in low educated women.

Our results indicated that HBV infection was associated with high risk of preterm labor, but maternal age and educational level could modify the association between HBV infection and preterm labor.