The duration of labor and rupture of membranes do not impact the risk of hepatitis B virus vertical transmission in infants after standard hepatitis B vaccinations and hepatitis B virus immunoglobulin administration, according to a study published in the European Journal of Obstetrics & Gynecology and Reproductive Biology.

Researchers in this prospective, multicenter, observational study evaluated the impact of membrane rupture and labor on the risk of hepatitis B vertical transmission between mother and infants born in Hong Kong between 2014 and 2016 (N=641). All women included in the final analysis had been identified as hepatitis B surface antigen (HBsAg) positive at their initial prenatal visit, were not on antiviral therapy, and carried their pregnancies to term.

Mothers were regularly evaluated until delivery, and by 12 hours after birth, all infants were given 10 μg  of hepatitis B vaccine and 110 IU hepatitis B immunoglobulin, with the same dose of hepatitis B vaccine repeated at months 1 and 6. Durations of labor, rupture of membranes, and mode of delivery were collected, and primary outcome was immunoprophylaxis failure, defined as positive HBsAg status for infants at 9 to 12 months.

No statistically significant difference in duration of labor, duration of rupture of membranes, mode of delivery, gestational age at delivery, preterm rupture of membranes, preterm delivery, birth weight, gravida, or parity were found after the analyses of the 641 pregnancies (P >.05). Immunoprophylaxis failure occurred in only 1% of pregnancies and only in women with viral loads greater than 7 log10 IU/ml and 8 log10 IU/ml, but subgroup analysis still found no significant associations between duration of labor and duration of rupture of membranes and immunoprophylaxis failure.

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Study investigators concluded that “[a]fter standard immunization to newborn, prolonged duration of [rupture of membranes] and labour would not affect the rate of vertical transmission even in HBV women with high viral load.”

Reference

Cheung KW, Seto MTY, So PL, et al. The effect of rupture of membranes and labour on the risk of hepatitis B vertical transmission: prospective multicentre observational study [published online November 23, 2018]. Eur J Obstet Gynecol Reprod Biol. doi: 10.1016/j.ejogrb.2018.11.017