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BACKGROUND The safety of hepatitis B vaccination during pregnancy has not been well studied. OBJECTIVE We characterized adverse events (AEs) after hepatitis B vaccination of pregnant women reported to the Vaccine Adverse Event Reporting System (VAERS), a spontaneous reporting surveillance system. METHODS We searched VAERS for AEs reports involving pregnant women who received hepatitis B vaccine from January 1, 1990-June 30, 2016. All reports and available medical records were reviewed by physicians. Observed AEs were compared to expected AEs and known rates of pregnancy outcomes to assess for any unexpected safety concern. RESULTS We found 192 reports involving pregnant women following hepatitis B vaccination of which 110 (57.3%) described AEs; 12 (6.3%) were classified as serious; one newborn death was identified in a severely premature delivery, and there were no maternal deaths. Eighty-two (42.7%) reports did not describe any AEs. Among pregnancies for which gestational age was reported, most women were vaccinated during the first trimester, 86/115 (74.7%). Among reports describing an AE, the most common pregnancy-specific outcomes included spontaneous abortion in 23 reports, preterm delivery in 7 reports, and elective termination in 5 reports. The most common non-pregnancy specific outcomes were general disorders and administration site conditions, such as injection site and systemic reactions, in 21 reports. Among 22 reports describing an AE among infants born to women vaccinated during pregnancy, 5 described major birth defects each affecting different organ systems. CONCLUSION Our analysis of VAERS reports involving hepatitis B vaccination during pregnancy did not identify any new or unexpected safety concerns.