Distribution of maternal and infant human papillomavirus: risk factors associated with vertical transmission

To evaluate the rate of human papillomavirus (HPV) infection in pregnant women and their neonates, and the risk factors associated with vertical transmission of HPV infection from mothers to neonates.

Cervical HPV testing was undertaken in pregnant women over 36 weeks of gestation, and mouth secretions and oral mucosa of neonates were tested for HPV immediately after delivery. HPV-positive neonates were rechecked 2 months postpartum to identify the persistence of HPV infection. In HPV-positive mothers, the placenta, cord blood and maternal peripheral blood were also analysed for HPV to confirm whether transplacental HPV infection occurred.

HPV was detected in 72 of 469 pregnant women (15.4%) and in 15 neonates (3.2%). Maternal HPV positivity was associated with primiparity and abnormal cervical cytology. The rate of vertical transmission was 20.8%, and all HPV-positive neonates were born from HPV-positive mothers. Vertical transmission was associated with vaginal delivery and multiple HPV types in the mother. Neonates with HPV showed a tendency for higher maternal total HPV copy number than neonates without HPV, but this difference was not significant (p=0.081). No cases of HPV infection were found in the infants at 2 months postpartum, and no HPV was detected in placenta, cord blood or maternal blood.

Vertical transmission of HPV is associated with vaginal delivery and multiple HPV types in the mother; however, neonatal HPV infection through vertical transmission is thought to be a transient.