Consequences of controlling viral diseases during pregnancy: Antiherpetic medication and influenza vaccination

The treatment and prevention of viral diseases during pregnancy are common concerns for medical providers and pregnant women, yet evidence regarding risks associated with these interventions is sparse.;In study 1 we evaluated the association between antiherpetic medication use and the risk of gastroschisis, an abdominal wall birth defect, among women who participated in the National Birth Defects Prevention Study from 1997-2007. The mothers of 0.7% (n=7) of 941 gastroschisis cases and 0.3% (n=22) of 8,339 non-malformed controls reported antiherpetic medication use during the first trimester of pregnancy; after adjustment for confounders, the risk of gastroschisis was twice as high among women using antiherpetic medication during the first trimester compared with those reporting no use of antiherpetics during pregnancy. Our study raises the possibility of a modest adverse effect of either antiherpetic medication use during the first trimester or the herpes infection for which it was presumably indicated.;In study 2 we examined the association between seasonal influenza vaccination during pregnancy and the risk of preterm birth (< 37 weeks' gestation) among a retrospective cohort of 2,279 mothers of non-malformed infants who participated in the Slone Birth Defect Study from 2006-2011. One third of women reported influenza vaccination during pregnancy and approximately 7% (n=164) experienced a preterm birth. We observed a null association between influenza vaccination at any time during pregnancy and the risk of preterm birth, after adjustment for confounders.;For study 3 we evaluated the association between seasonal influenza vaccination during pregnancy and the risk of small infant size, also among mothers of non-malformed infants participating in the Slone Birth Defect Study from 2006-2011. Small infant size was defined as small for gestational age (SGA), i.e. <10 th percentile in weight given gestational week of delivery, using both sex-specific birthweight references values (SGAr) and a customized standard (SGAc). Respectively, 9.6% (n=214) and 10.3% (n=229) of infants were classified as SGAr and SGAc. We observed modest protective associations between influenza vaccination during pregnancy and the risks of SGAr and SGAc. Together with Study 2, these findings provide some support for the relative safety of influenza vaccination during pregnancy.