The herpes simplex virus 2 primarily affects the genital area and is usually, but not always, sexually transmitted. So what are the implications for a pregnant woman and her baby? The risk of neonatal infection is highest for the baby when herpes simplex virus 2 is contracted during the third trimester. Antiviral treatments are called for, but only for severe cases. Acyclovir which is used to treat this virus is found safe for pregnant women. In case it is too late to treat the HSV-2 (if it was contracted late in the third trimester or near delivery), elective Cesarean is recommended.