Varicella vaccine exposure during pregnancy: Data from 10 years of the pregnancy registry

Background. The Pregnancy Registry for Varivax (Merck) was established to monitor for congenital varicella syndrome or other birth defects in the offspring of women who were exposed to varicella vaccine while pregnant. Methods. The registry receives voluntary reports from health care providers or consumers about women given the vaccine 3 months before or during pregnancy. Follow-up is conducted to obtain and classify pregnancy outcomes. All reports are evaluated for the presence of birth defects. Outcomes from prospectively reported pregnancy exposures are used to calculate rates and 95% confidence intervals. Results. From 17 March 1995 through 16 March 2005, 981 women were enrolled. Pregnancy outcomes were available for 629 prospectively enrolled women. Among the 131 live births to varicella-zoster virus-seronegative women, there was no evidence of congenital varicella syndrome (rate, 0% [95% confidence interval {CI}, 0%-6.7%]), and major birth defects were observed in 3 infants (rate, 3.7% [ 95% CI, 0.8%-10.7%]). Conclusions. Although the numbers of exposures are not sufficient to rule out a very low risk, data collected in the pregnancy registry to date do not support a relationship between the occurrence of congenital varicella syndrome or other birth defects and varicella vaccine exposure during pregnancy.