Vaginal Delivery and Breastfeeding Benefit Infant Immune Response to Hepatitis B Vaccine: A Prospective Cohort Study.

Background and aims: Natural vaginal delivery and breastfeeding favor the development of a strong immune system in infants, and the immune response of infants to vaccines is closely related to their immune system. This large prospective cohort study aimed to explore the effects of delivery and feeding mode on infant's immune response to hepatitis B vaccine (HepB).

Methods: A total of 1,254 infants who completed the whole course of HepB immunization and whose parents were both HBsAg negative were enrolled from infants born in Jinchang City during 2018-2019 by cluster sampling method.

Results: Twenty (1.59%) of the 1,254 infants were nonresponders to HepB. Among the other 1,234 infants, 10.05% (124/1,234), 81.69% (1,008/1,234) and 8.27% (102/1,234) of infants had low, medium, and high responses to HepB, respectively. Logistic regression analysis showed that cesarean section (OR: 8.58, 95% CI: 3.11-23.65, p<0.001) and birth weight <3.18 kg (OR: 5.58, 95% CI: 1.89-16.51, p=0.002) were independent risk factors for infant nonresponse to HepB, and cesarean section (OR: 7.63, 95% CI: 4.64-12.56, p<0.001), formula feeding (OR: 4.91, 95% CI: 1.47-16.45, p=0.001), maternal anti-HBs negativity (OR: 27.2, 95% CI: 10.67-69.35, p<0.001), paternal non-response history of HepB (OR: 7.86, 95% CI: 2.22-27.82, p=0.014) and birth weight <3.22 kg (OR: 4.00, 95% CI: 2.43-6.59, p<0.001) were independent risk factors for infant low response to HepB. In cases where birth weight and genetic factors are unmodifiable and maternal anti-HBs effects are controversial, it makes sense to enhance infant response by changing delivery and feeding patterns.

Conclusions: Natural vaginal delivery and breastfeeding are beneficial to the infant's immune response to HepB.