Acyclovir in pregnancy registry: six years' experience. The Acyclovir in Pregnancy Registry Advisory Committee.

The Acyclovir in Pregnancy Registry was established to gather data on prenatal exposure to acyclovir. Exposed pregnancies are tracked prospectively to ascertain exposure, risk factors, and pregnancy outcome. Through June 30, 1990, 312 acyclovir-exposed pregnancies had been reported and followed. Of these, 239 were exposed during the first trimester; outcomes included 24 spontaneous fetal losses, 47 induced abortions, 159 live births of infants without congenital abnormalities, and nine outcomes with congenital abnormalities. Among the 73 second- and third-trimester exposures, one infant was born with an abnormality. Exposures are also reported to the registry retrospectively, ie, after the outcome of pregnancy is known. Registry findings to date do not show an increase in the number of birth defects among the prospective reports when compared with that expected in the general population, and there is no consistent pattern of abnormalities among retrospective or prospective reports. These findings should provide some reassurance in counseling women following inadvertent prenatal exposure. The cases accumulated to date represent a sample of insufficient size for reaching reliable and definitive conclusions about the safety of acyclovir for pregnant women and their developing fetuses. Therefore, until further information is available, the Acyclovir in Pregnancy Registry Advisory Committee recommends following the 1989 Centers for Disease Control Sexually Transmitted Diseases Treatment Guidelines for the use of acyclovir in pregnancy, and encourages reporting of all prenatal exposures to the registry (1-800-722-9292, ext. 8465).