Parent-to-Child Infection Transmission: Routes, Risks & Prevention

Perinatal/vertical transmission refers to infection passing from parent to child before, during, or after birth.

1. In Utero (Transplacental)

Pathogen crosses placenta → fetal infection.

• Viruses: CMV, rubella, HSV, HIV, syphilis (Treponema), Zika, parvovirus B19
• Parasites: Toxoplasma gondii

2. Intrapartum (During Delivery)

Exposure to maternal genital tract secretions/blood.

• Bacteria: Group B Strep (GBS), E. coli, gonorrhea, chlamydia
• Viruses: HSV (high risk if primary outbreak), HIV (without ART)

3. Postpartum

• Breast milk: HIV (if not on ART/suppressed), CMV, HTLV-1
• Close contact: Respiratory viruses (flu, RSV, COVID), skin infections (staph, HSV), enteric pathogens

Prevention Strategies

• Prenatal screening & treatment: HIV, syphilis, HBV, HCV, GBS, CMV counseling
• ART for HIV+ mothers: Suppress viral load <50 copies/mL → transmission <1%
• GBS prophylaxis: Intrapartum penicillin for colonized mothers
• Cesarean for HSV lesions: If active genital lesions at labor
• Infant prophylaxis: Hep B vaccine + HBIG at birth; HIV-exposed infant ART; eye prophylaxis for gonorrhea/chlamydia
• Safe feeding: Avoid breastfeeding if HIV+ (in resource-rich settings); pasteurize donor milk
• Hygiene & vaccination: Handwashing, caregiver Tdap/flu/COVID vaccines

Comprehensive perinatal care dramatically reduces vertical transmission for most pathogens.