Studies on placentae and infants from women vaccinated for smallpox during pregnancy.

Sixty-five placentae from women who had been vaccinated while pregnant were examined for the presence of the inclusion bodies of vaccinia. Also suspensions from 40 of the placentae were inoculated into the chorio-allantoic membrane of chick embryos in an attempt to culture any vaccinia virus present. Both these studies gave negative results.The results of the pregnancies of these 65 women showed no increase in the incidence of abortion, stillbirth, or congenital abnormalities, over the unvaccinated women in the overall series.