Chronic Maternal Hepatitis B Virus Infection and Pregnancy Outcome - A Single Center Study in Kunming, China

Abstract

Background: Chinese population has a high prevalence of chronic hepatitis B virus (HBV) infection, the impact of which on pregnancy outcome remains controversial. A single-center retrospective cohort study was performed in Kunming, a multi-ethnic city in south-western China to examine this issue. Methods: The singleton pregnancies delivering at ≥28 weeks gestation under our care in 2005-2017 constituted the study cohort. Maternal characteristics and pregnancy outcome were compared between mothers with and without seropositivity for hepatitis B surface antigen (HBsAg) determined at routine antenatal screening. Results: Among the 49,479 gravidae in the cohort, the 1624 (3.3%) HBsAg seropositive gravidae had a lower incidence of nulliparity (RR 0.963, 95% CI 0.935-0.992) and having received tertiary education (RR 0.829, 95% CI 0.784-0.827). There was no significant difference in the medical history, pregnancy complications, or labor or perinatal outcome, except that HBV carriers had significantly lower incidence of labor induction (RR 0.827, 95% CI 0.714-0.958) and of small-for-gestational age (SGA) infants (RR 0.854, 95% CI 0.734-0.994). On regression analysis, maternal HBV carriage was independently associated with spontaneous labor (aRR 1.231, 95% CI 1.044-1.451) and reduced SGA infants (aRR 0.842, 95% CI 0.712-0.997). Conclusions: Our 3.3% prevalence of maternal HBV infection was around the lower range determined in the Chinese population. The association with spontaneous labor and reduced SGA infants could have helped to promote the perpetuation of the infection through enhanced survival of the offspring infected at birth, thus explaining the high prevalence in the Chinese population.

Maternal hepatitis B surface antigen carrier status and pregnancy outcome: a retrospective cohort study

“…In this study, we investigated the outcomes of 735 pregnant women with HBsAg carrier status and 18 693 cases in a nonexposed group of subjects in Hangzhou, China. We found that the proportion of positive maternal HBsAg carrier was 3.78%; this was slightly higher than the 3.3% rate reported previously in Kunming, China [18]. In China, people such as medical staff, nursery staff, patients receiving organ transplants, people frequently accessible to blood transfusions, blood products or intravenous drug, people with poor immunity or vulnerable to trauma, people with multiple sexual partners or with family members of HBsAg-positive, etc., are under high risk of hepatitis B [19].…”

Obstetric implications of maternal chronic hepatitis B virus infection

“…Nevertheless, a number of other studies [18][19][20][21][22][23][24][25][26][27][28] did not demonstrate such an association. The reasons for the conflicting findings have not been elucidated, but several factors could be involved.…”

“…Paradoxically, HBV carriage also appears to confer some reproductive advantage in form of reduction in hypertension in pregnancy, especially PE, as well as enhanced fetal growth manifesting as reduction in LBW/SGA infants, and increase in birthweight as well as LGA and macrosomic infants. Indeed, a significant proportion of the studies found no or minimally increased adverse obstetric outcome in HBV carriers, and it was suggested that chronic HBV infection may have evolved to become synergistic with human reproduction in order to facilitate its transmission down successive human generations to perpetuate the infection in its primary host [28]. Most of the available studies on this topic are retrospective and are limited in the available information especially regarding the mechanisms or explanations involved in the association between chronic HBV infection with various reported outcomes.…”

“…A number of studies, examining this issue from different angles, suggest that maternal chronic HBV infection probably enhances fetal growth in utero. Some studies have found significant reduction in SGA infants, 20-25% in one study [11], 21% in another [18], and 16% in a third [28]. Interestingly, one study found reduction in SGA infants (OR 0.68) only among women who had CD [27].…”

“…Increased LBW infants [11,23,54,67] Increased in HBeAg positive [13] Increased SGA infants [11,67] Reduced [11,18,28,68] Reduced SGA in CD [27] Large-for-gestational age (LGA) and macrosomic infants Increased birthweight in Oriental Chinese women [24,47] Increased LGA/macrosomia [12,48,68] Increased in HBeAg negative [26] Fetal distress and birth asphyxia Increased [22,23,48,56]…”