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Vaccine. 2019 Oct 16;37(44):6648-6655. doi: 10.1016/j.vaccine.2019.09.043. Epub 2019 Sep 20.

Uptake and safety of hepatitis A vaccination during pregnancy: A Vaccine Safety Datalink study.

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Center for Health Research, Kaiser Permanente Northwest, Portland, OR, United States. Electronic address:
Center for Health Research, Kaiser Permanente Northwest, Portland, OR, United States.
HealthPartners Institute, Minneapolis, MN, United States.
Institute for Health Research, Kaiser Permanente Colorado, Aurora, CO, United States.
Marshfield Clinic Research Institute, Marshfield, WI, United States.
Research and Evaluation, Kaiser Permanente Southern California, Pasadena, CA, United States.
Kaiser Permanente Washington Health Research Institute, Seattle, WA, United States.
Kaiser Permanente Vaccine Study Center, Kaiser Permanente Northern California, Oakland, CA, United States.
Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, GA, United States.



Infection with hepatitis A virus (HAV) during pregnancy, although uncommon, is associated with gestational complications and pre-term labor. Hepatitis A vaccine (HepA) is recommended for anyone at increased risk for contracting hepatitis A, including women at risk who are also pregnant. Limited data are available on the safety of maternal HepA vaccination.


Assess the frequency of maternal HepA receipt and evaluate the potential association between maternal vaccination and pre-specified maternal and infant safety outcomes.


A retrospective cohort of pregnancies in the Vaccine Safety Datalink (VSD) resulting in live births from 2004 through 2015 was included. Pregnancies with HepA exposure were compared to those with other vaccine exposures, and to those with no vaccine exposures. Risk factors for contracting hepatitis A were identified up to one-year prior to or during the pregnancy using ICD-9 codes. Maternal and fetal adverse events were evaluated according to maternal HepA exposure status. Adjusted odds ratio (OR) were used to describe the association.


Among 666,233 pregnancies in the study period, HepA was administered at a rate of 1.7 per 1000 (n = 1140), most commonly within the first six weeks of pregnancy. Less than 3% of those exposed to HepA during pregnancy had an ICD-confirmed risk factor. There were no significant associations between HepA exposure during pregnancy and gestational hypertension, gestational diabetes, pre-eclampsia/eclampsia, cesarean delivery, pre-term delivery, and low birthweight. There was a statistically significant association between HepA exposure during pregnancy and small-for-gestational age (SGA) infants (aOR 1.32, [95% CI 1.09, 1.60], p = 0.004).


The rate of maternal HepA vaccination was low and rarely due to documented risk factors for vaccination. HepA vaccination during pregnancy was not associated with an increased risk for a range of adverse events examined among pregnancies resulting in live births, but an identified association between maternal HepA and SGA infant outcomes, while likely due to unmeasured confounding, warrants further exploration.


Hepatitis A; Maternal immunization; Pregnancy; Vaccination; Vaccine safety

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