Women with an active HSV infection can reduce the risk of fetal transmission with a C-section.
In developed countries widespread HIV testing and anti-retroviral therapy have reduced maternal-fetal transmission dramatically.
Sometimes a fetal infection can be diagnosed using ultrasound.
Factors that may increase the risk of maternal HIV transmission include the the amount of HIV in her blood; use of illicit drugs; severe inflammation of the fetal membranes; and, a prolonged period between membrane rupture and delivery.
The fetal infection rate is above 60% if maternal infection occurs during the third trimester, but the most severe fetal complications occur with first-trimester infection.
Prevention of maternal-to-fetal HSV transmission includes abstaining from sexual activity during the last trimester; using a condom; postponing membrane rupture; avoiding a fetal monitor; and, avoiding vacuum or forceps deliveries.
Precautions for preventing fetal exposure to HIV-infected maternal blood include avoiding: amniocentesis, fetal scalp blood sampling, premature rupturing of the fetal membranes.
Routine vaccinations have made prenatal infection rare in the developed world.
The two methods of fetal monitoring counting are electronic fetal monitoring (EFM), which uses ultrasound to track the baby's heart rate, and counting fetal movements, which involves the mother keeping track of the baby's movements to ensure they are active and healthy.
Zidovudine (ZDV, AZT, Retrovir) is the only drug that has been proven to help prevent fetal HIV infection.
placenta
Most GBS-carriers are treated with intravenous antibiotics--from membrane rupture through labor--to prevent fetal transmission.
Lallemant, M., et al. "Single-dose Prenatal Nevirapine plus Standard Zidovudine to Prevent Mother-to-Child Transmission of HIV-1 in Thailand." New England Journal of Medicine 351, no. 3 (July 15, 2004): 217-28.