Fetal Risk Summary

Rabies vaccine (human) is an inactivated virus vaccine (1,2). Animal reproduction studies have not been conducted with the vaccine.

Because rabies is nearly 100% fatal if contracted, the vaccine should be given for postexposure prophylaxis (1,2). Fetal risk from the vaccine is unknown, but indications for prophylaxis are not altered by pregnancy (1). Three reports described the use of rabies vaccine (human) during pregnancy (3,4 and 5). Passive immunity was found in one newborn (titer >1:50) but was lost by 1 year of age (3). No adverse effects from the vaccine were noted in the newborn. The mother had not delivered at the time of the report in the second case (4).

A 1990 brief report described the use of rabies vaccine in 16 pregnant women, 15 using the human diploid cell vaccine and 1 receiving the purified chick embryo cell product (5). In 15 cases the stage of pregnancy was known: nine 1st trimester, three 2nd trimester, and three 3rd trimester. Two women had spontaneous abortions, but the causes were probably not vaccine related. The remaining pregnancy outcomes were 12 full-term healthy newborns, 1 premature delivery at 36 weeks' gestation, and 1 newborn with grand-mal seizures on the 2nd day. In the latter case, no antirabies antibodies were detectable in the infant's serum, indicating that the condition was not vaccine related (5).

In two reports, duck embryo–cultured vaccine was used during pregnancy (6,7). In 1974 a report appeared describing the use of rabies vaccine (duck embryo) in a woman in her 7th month of pregnancy (6). She was given a 21-day treatment course of the vaccine. She subsequently delivered a healthy term male infant who was developing normally at 9 months of age. The second case was described in 1975 involving a woman exposed to rabies at 35 weeks' gestation (7). She was treated with a 14-day course of vaccine (duck embryo) followed by three booster injections. She gave birth at 39 weeks' gestation to a healthy male infant. Cord blood rabies neutralizing antibody titer was 1:30, indicative of passive immunity, compared with a titer of 1:70 in maternal serum. Titers in the infant fell to 1:5 at 3 weeks of age, then to <1:5 at 6 weeks. Development was normal at 9 months of age.

A 1989 report from Thailand described the use of purified Vero cell rabies vaccine for postexposure vaccination in 21 pregnant women (8). Equine rabies immune globulin was also administered to 12 of the women with severe exposures. One patient aborted 3 days after her first rabies vaccination, but she had noted vaginal bleeding on the day of rabies exposure. No congenital malformations were observed and none of the mothers or their infants developed rabies after a 1-year follow-up (8).

In a subsequent prospective study, the above researchers administered the purified Vero cell rabies vaccine (5-dose regimen) after exposure to 202 pregnant women (9). Some of these women also received a single dose of rabies immune globulin (human or equine). Follow-up of 1 year or greater was conducted in 190 patients; 12 patients were lost to follow-up following postexposure treatment. No increase in maternal (spontaneous abortion, hypertension, placenta previa, or gestational diabetes) or fetal (stillbirth, minor birth defect, or low birth weight) complications was observed in comparison with a control group of nonvaccinated, nonexposed women. The one minor congenital defect observed in the treated group was a type of club foot (talipes equinovalgus).

Breast Feeding Summary

No data are available.

References

1. American College of Obstetricians and Gynecologists. Immunization during pregnancy. Technical Bulletin. No. 160, October 1991.
2. Amstey MS. Vaccination in pregnancy. Clin Obstet Gynaecol 1983;10:13–22.
3. Varner MW, McGuinness GA, Galask RP. Rabies vaccination in pregnancy. Am J Obstet Gynecol 1982;143:717–8.
4. Klietmann W, Domres B, Cox JH. Rabies post-exposure treatment and side-effects in man using HDC (MRC 5) vaccine. Dev Biol Stand 1978;40:109–13.
5. Fescharek R, Quast U, Dechert G. Postexposure rabies vaccination during pregnancy: experience from post-marketing surveillance with 16 patients. Vaccine 1990;8:409–10.
6. Cates W Jr. Treatment of rabies exposure during pregnancy. Obstet Gynecol 1974;44:893–6.
7. Spence MR, Davidson DE, Dill GS Jr, Boonthai P, Sagartz JW. Rabies exposure during pregnancy. Am J Obstet Gynecol 1975;123:655–6.
8. Chutivongse S, Wilde H. Postexposure rabies vaccination during pregnancy: experience with 21 patients. Vaccine 1989;7:546–8.
9. Chutivongse S, Wilde H, Benjavongkulchai M, Chomchey P, Punthawong S. Postexposure rabies vaccination during pregnancy: effect on 202 women and their infants. Clin Infect Dis 1995;20:818–20.