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Maternal pre-pregnancy infection with hepatitis B virus and the risk of preterm birth: a population-based cohort
Jue Liu1, Shikun Zhang2, Min Liu3
1Department of Child, Adolescent and Women's Health, School of Public Health, Peking University, Beijing, China.
Insights
Maternal hepatitis B virus infection before pregnancy increases the risk of preterm and early preterm birth. Early detection and intervention are crucial for improving maternal and neonatal outcomes.
Area of Science:
- Obstetrics and Gynecology
- Infectious Diseases
- Public Health
Background:
- Preterm birth is a leading cause of child mortality globally.
- Maternal hepatitis B virus (HBV) infection is linked to preterm birth in developed nations.
- Limited data exist from China and other developing countries regarding this association.
Purpose of the Study:
- To investigate the association between pre-pregnancy hepatitis B virus infection and the risk of preterm and early preterm birth in China.
- To provide evidence for public health strategies in regions with intermediate to high HBV prevalence.
Main Methods:
- Population-based cohort study of 489,965 rural Chinese women with singleton livebirths (2010-2012).
- Classification of participants into uninfected, HBsAg positive/HBeAg negative, and HBsAg positive/HBeAg positive groups.
- Log-binomial regression used to calculate adjusted risk ratios (aRR) for preterm (<37 weeks) and early preterm (<34 weeks) birth.
Main Results:
- Maternal pre-pregnancy HBV infection was associated with increased risk of preterm birth.
- HBsAg positive/HBeAg negative women had a 26% higher risk of preterm birth (aRR 1.26).
- HBsAg positive/HBeAg positive women had a 20% higher risk of preterm birth (aRR 1.20) and a 34% higher risk of early preterm birth (aRR 1.34).
Conclusions:
- Maternal pre-pregnancy hepatitis B virus infection is an independent risk factor for preterm and early preterm birth.
- The risk of preterm birth due to HBV infection warrants attention beyond mother-to-child transmission.
- Comprehensive preconception screening and intervention programs for HBV are recommended to improve maternal and neonatal outcomes.
Background:
Preterm birth is the leading cause of child death in children younger than 5 years. Large cohort studies in developed countries have shown that maternal hepatitis B virus infection is associated with preterm birth, but there is little reliable evidence from China and other developing countries, where hepatitis B virus prevalence is intermediate or high. Hence, we designed this study to investigate the association between pre-pregnancy hepatitis B virus infection and risk of preterm and early preterm birth.
Methods:
Between Jan 1, 2010, and Dec 31, 2012, we did a population-based cohort study using data from 489 965 rural women aged 21-49 years who had singleton livebirths from 220 counties of China who participated in the National Free Preconception Health Examination Project. Participants were divided into three groups according to their pre-pregnancy status of hepatitis B virus infection: women uninfected with hepatitis B virus (control group), women who were HBsAg positive and HBeAg negative (exposure group 1), and women who were both HBsAg and HBeAg positive (exposure group 2). The primary outcome was preterm birth (gestation at less than 37 weeks). We used log-binomial regression to estimate adjusted risk ratios (aRR) of preterm birth for women with pre-pregnancy hepatitis B virus infection, and risk of early preterm birth (gestation less than 34 weeks).
Findings:
489 965 women met inclusion criteria and were included in this study; of these, 20 827 (4·3%) were infected with hepatitis B virus. Compared with women who were not infected with hepatitis B virus, women who were HBsAg positive and HBeAg negative had a 26% higher risk of preterm birth (aRR 1·26, 95% CI 1·18-1·34) and women who were both HBsAg and HBeAg positive had a 20% higher risk of preterm birth (aRR 1·20, 1·08-1·32). Compared with women who were not infected with hepatitis B virus, women who were HBsAg positive and HBeAg negative manifested an 18% higher risk of early preterm birth (gestation less than 34 weeks; aRR 1·18, 1·04-1·34) and women who were both HBsAg and HBeAg positive had a 34% higher risk of early preterm birth (aRR 1·34, 1·10-1·61). Maternal pre-pregnancy hepatitis B virus infection was independently associated with higher risk of preterm birth and early preterm birth. These associations were similar in subgroups of participants as defined by baseline characteristics.
Interpretation:
Besides mother-to-child transmission, the risk of preterm birth in women infected with hepatitis B virus should not be neglected. Comprehensive programmes that focus on early detection of hepatitis B virus infection before pregnancy and provide appropriate medical intervention for women infected with hepatitis B virus before and during pregnancy would be helpful in improving maternal and neonatal outcomes and reducing child mortality.
Funding:
Chinese Association of Maternal and Child Health Studies.
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