Vertical Transmission (Mother-to-Child Transmission)

How infections pass from mother to baby

The "TORCH" acronym groups congenital infections: Toxoplasmosis, Other (syphilis, varicella, parvovirus, Zika), Rubella, Cytomegalovirus and Herpes.

Key infections and prevention

HIV

Without treatment, a substantial proportion of babies born to mothers with HIV become infected during pregnancy, birth or breastfeeding. With effective antiretroviral therapy and an undetectable viral load, plus medicine for the baby after birth, the risk falls to under 1%. All pregnant people are offered HIV testing. See HIV/AIDS.

Hepatitis B

Babies infected at birth have a very high chance, about 90%, of developing chronic infection. Prevention:

• testing all pregnant people for hepatitis B surface antigen
• antiviral medicine in late pregnancy for mothers with high viral loads
• hepatitis B vaccine and hepatitis B immune globulin within 12 hours of birth for babies of infected mothers, then completing the vaccine series

See hepatitis B.

Syphilis

Syphilis crosses the placenta and can cause miscarriage, stillbirth or congenital syphilis with bone, skin, liver and brain problems. US cases of congenital syphilis have risen sharply. Screening at the first prenatal visit, and again in the third trimester and at delivery for many people, with penicillin treatment, prevents most cases.

Cytomegalovirus (CMV)

CMV is the most common congenital infection. Most babies have no symptoms, but some develop hearing loss, small head size, developmental delay or vision problems. Pregnant people can reduce risk by washing hands after diaper changes and avoiding sharing utensils or kissing young children on the mouth. Some newborns are screened for CMV, and antiviral treatment helps selected babies.

Herpes simplex

Neonatal herpes is rare but serious, mostly from mothers who acquire genital herpes late in pregnancy. Antiviral medicine from 36 weeks for those with a history of herpes, and cesarean delivery if active lesions are present at labor, reduce risk.

Group B strep

Group B strep bacteria live harmlessly in many people's gut and genital tract but can cause sepsis, pneumonia or meningitis in newborns. Screening at 36 to 37 weeks and IV antibiotics during labor for carriers greatly reduce early-onset infection.

Toxoplasmosis

A parasite from undercooked meat and cat feces. Toxoplasmosis can cause eye and brain damage in the baby. Cook meat thoroughly, wash produce, wear gloves when gardening and avoid changing cat litter if possible.

Zika, rubella and chickenpox

• Zika virus: can cause microcephaly. Avoid travel to areas with active Zika transmission during pregnancy and when trying to conceive
• rubella: congenital rubella syndrome causes deafness, heart defects and cataracts. Prevented by MMR vaccination before pregnancy
• chickenpox: can cause congenital varicella syndrome. Non-immune people should be vaccinated before pregnancy

Hepatitis C

About 5% of babies born to mothers with active hepatitis C infection become infected. All pregnant people are now screened, and infants of positive mothers are tested.

Prenatal screening

US guidelines recommend testing all pregnant people for:

• HIV
• hepatitis B
• hepatitis C
• syphilis
• rubella immunity
• chlamydia and gonorrhea for those at risk or under 25
• group B strep at 36 to 37 weeks

Breastfeeding

Breastfeeding is safe and recommended with most infections, including hepatitis B (once the baby is vaccinated) and hepatitis C (unless nipples are cracked and bleeding). In the US, people with HIV have traditionally been advised not to breastfeed, but current guidance supports shared decision-making for those with a sustained undetectable viral load.

Frequently asked questions

What is vertical transmission?

Vertical transmission is when an infection passes from a mother to her baby during pregnancy, labor and birth, or breastfeeding. Examples include HIV, hepatitis B, syphilis, cytomegalovirus, herpes and group B strep.

Which infections can be passed from mother to baby?

Common examples are HIV, hepatitis B and C, syphilis, cytomegalovirus, herpes simplex, group B strep, toxoplasmosis, rubella, chickenpox, Zika and parvovirus. Some cross the placenta, while others pass during birth or through breast milk.

How can mother-to-child transmission be prevented?

Prevention includes prenatal screening for infections, vaccines before and during pregnancy, treating infections such as HIV, syphilis and hepatitis B during pregnancy, antibiotics in labor for group B strep, and newborn vaccines and medicines.

Can a mother with HIV have a healthy baby?

Yes. With effective HIV treatment that keeps the viral load undetectable during pregnancy and delivery, plus medicine for the baby after birth, the chance of passing HIV to the baby is under 1%.

What are TORCH infections?

TORCH infections are a group of infections that can pass to a baby during pregnancy and cause birth defects: Toxoplasmosis, Other infections (including syphilis, chickenpox, parvovirus and Zika), Rubella, Cytomegalovirus and Herpes simplex.