Experts say there's some risk of passing along the herpes virus to a fetus Ia newborn child. But there are ways to whlie oral sex safer during pregnancy. Is it reasonable to ask women to avoid oral sex during pregnancy to help stop the spread of herpes? In recent weeks, several outlets have published articles about the dangers of oral sex and the transmission of genital herpes during pregnancy. To lessen this risk, some medical practitioners and health writers have advised women to avoid oral sex entirely during the third trimester of pregnancy.