Question:medium
Maximum chance of transmission to the baby during delivery is seen with which infection?
Maximum chance of transmission to the baby during delivery is seen with which infection?
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Which virus infects the baby by contact in the birth canal rather than across the placenta?
Updated On: Jun 24, 2026
- HSV (Herpes simplex virus)
- CMV (Cytomegalovirus)
- VZV (Varicella zoster virus)
- Rubella
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Separate the listed viruses by their main route to the baby. Some cross the placenta in utero, while others are picked up as the baby passes through the birth canal. The stem specifically asks about transmission during delivery.
Step 2: CMV, rubella and varicella zoster are predominantly transplacental agents, so the fetus is usually infected well before labour begins. They therefore do not fit a delivery-time peak of transmission.
Step 3: Herpes simplex virus behaves differently. It rarely crosses the placenta. Instead the newborn becomes infected by direct contact with infectious secretions from the cervix and lower genital tract while being born vaginally. This is why an active genital herpes lesion at term is an indication for caesarean delivery.
Step 4: Since contact during vaginal birth is the chief route for HSV, it carries the maximum chance of transmission during delivery.
\[\boxed{\text{HSV}}\]
Step 2: CMV, rubella and varicella zoster are predominantly transplacental agents, so the fetus is usually infected well before labour begins. They therefore do not fit a delivery-time peak of transmission.
Step 3: Herpes simplex virus behaves differently. It rarely crosses the placenta. Instead the newborn becomes infected by direct contact with infectious secretions from the cervix and lower genital tract while being born vaginally. This is why an active genital herpes lesion at term is an indication for caesarean delivery.
Step 4: Since contact during vaginal birth is the chief route for HSV, it carries the maximum chance of transmission during delivery.
\[\boxed{\text{HSV}}\]
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