Impact of Maternal HBsAg Carrier Status on Neonatal Outcomes

Hepatitis B virions
Hepatitis B virions
Infants born to mothers who test positive for HBsAg are at higher risk for congenital malformations.

Infants born to mothers who test positive for hepatitis B surface antigen (HBsAg) are at increased risk for congenital malformations, according to an analysis of medical record data from hospitals located in Sichuan province, China. Results from the retrospective cohort study were published ahead of print in The Journal of Maternal Fetal & Neonatal Medicine.

HBsAg positivity is a common maternal comorbidity in 7.6% of women in China. Children of HBsAg-positive mothers are at high risk for chronic hepatitis B virus (HBV) infection; however, the impact of carrier status on other birth outcomes remains to be fully elucidated.

The question of whether positive maternal HBsAg carrier status causes preterm birth, low birth weight, and associated macrosomia had been previously studied, but sample sizes were small and the results inconsistent. For this study, Jin Tan of Sichuan University’s West China School of Public Health and co-investigators used a database of medical records from 6 Chinese hospitals to analyze maternal characteristics and prespecified neonatal outcomes for singleton births between January 1, 2009, and December 31, 2010. A total of 21,947 neonates and their mothers were included. Outcomes of interest were preterm birth (gestational age <37 weeks), low birth weight (<2500 g), macrosomia (>4000g), fetal malformation (diagnosed by systematic ultrasound examination during pregnancy), neonatal malformation (any visible malformation diagnosed by clinicians after birth), and 1-minute and 5-minute Apgar scores (<7).

Results showed a statistically significant association between maternal HBsAg positivity and both fetal and neonatal malformations (adjusted odds ratio (aOR) 2.23, 95% CI: 1.15-4.30; aOR 2.66, 95% CI: 1.38-5.14), and a lower risk of macrosomia (aOR 0.67, 95% CI: 0.47-0.96). The researchers postulated that the lower rate of macrosomia may be related to the effect of HBsAg on placental tissue compromising the fetal nutrient supply. HBsAg positivity was not significantly associated with preterm birth, low birth weight, or Apgar scores.

“In summary, maternal HBsAg carrier status was found to be associated with higher risk of fetal malformation and neonatal malformation, a finding that was not reported before,” wrote the authors in their conclusion. “HBsAg positivity was also associated with lower risk of macrosomia and non-significant higher risk of lower birth weight, suggesting the potential adverse impact on baby growth. Given the magnitude of population being infected [with] HBsAg both in China and [the] developing world, and the severity of congenital malformation on society and families, appropriate and [effective] counseling to pregnant women about potential risks in [antenatal] care is warranted.”

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Tan J, Huang S, He G, et al. Maternal hepatitis B surface antigen carrier status and its impact on neonatal outcomes: a cohort study of 21,947 singleton newborns in China. J Matern Fetal Neonatal Med. 2016 Oct 20.  doi: 10.1080/14767058.2016.1243098