In this article:
How Does Vertical Transmission Occur During Pregnancy?
Vertical transmission can occur through different routes:- In utero (transmission through the placenta): The pathogen crosses the placenta and reaches the baby before birth; this is also called transplacental transmission. Risk and outcome depend on the specific infection and the stage of pregnancy at which the mother becomes infected. This route applies to infections such as rubella, toxoplasmosis, syphilis, and Zika virus.
- Intrapartum transmission (during labour and delivery): The baby is exposed during delivery through contact with maternal blood, vaginal secretions, or other body fluids. HIV, group B Streptococcus (GBS), hepatitis B, and herpes simplex virus often spread this way. Risk depends on the infection and the mother's condition during delivery, and doctors may recommend specific medicines, preventive treatment, or changes to the delivery plan accordingly.
- Postpartum (transmission through breastfeeding): The infection passes after birth, mainly through breastfeeding. HIV can transmit through breast milk if the mother is not on effective antiretroviral treatment.
Can Vertical Transmission Be Prevented?
In many cases, prevention depends on identifying the infection early and following the recommended treatment or preventive measures.Important steps include:
- Getting recommended antenatal screening early in pregnancy
- Treating infections promptly
- Taking prescribed medicines correctly
- Following vaccination recommendations before or during pregnancy when appropriate
- Using appropriate precautions during labour and delivery
- Giving newborn preventive treatment or vaccination when indicated
- Following medical advice about breastfeeding when an infection can be transmitted through breast milk
"Vertical transmission can often be prevented or greatly reduced through antenatal screening, vaccination when appropriate, medicines for certain infections, careful planning of delivery and specific newborn care such as timely vaccination or preventive treatment."
Dr Chetana V, Sr. Consultant, Obs & Gyn, Aster CMI Hospital
How Is Vertical Transmission Diagnosed?
Antenatal screening is the main tool for catching vertical transmission risk early. A standard antenatal panel includes tests for HIV, hepatitis B surface antigen, syphilis (VDRL or RPR), and, where indicated, rubella and toxoplasmosis. When a test comes back positive, doctors act depending on the infection:- HIV-positive mothers start antiretroviral therapy, which lowers the baby's infection risk considerably and is continued through breastfeeding.
- Hepatitis B-positive mothers have their viral load checked; babies born to them receive a hepatitis B vaccine and immunoglobulin within hours of birth.
- Syphilis-positive mothers receive penicillin treatment, which prevents transmission when given early enough in pregnancy.
- Herpes outbreaks near the delivery date may lead doctors to recommend a caesarean section to avoid contact transmission.
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FAQs on What Is Vertical Transmission in Pregnancy?
- Does every baby exposed to an infected mother get infected?
No. Transmission risk depends on the specific infection, the mother's viral or bacterial load, the stage of pregnancy, and whether preventive treatment was given in time. - What is the difference between vertical and horizontal transmission?
Vertical transmission passes from mother to baby during pregnancy, birth, or breastfeeding. Horizontal transmission spreads through contact, droplets, or contaminated surfaces. - Which test checks for vertical transmission risk in pregnancy?
The standard antenatal panel tests for HIV, hepatitis B surface antigen, and syphilis at the first visit, with rubella and toxoplasmosis testing added when clinically indicated.