Evidence suggests that newborns are exposed perinatally to HPV. Vertical transmission of HPV was first reported by Hajek in 1956 in a case of juvenile laryngeal papillomatosis. Confirmation of the perinatal transmission in different mucosa (genital, oral, conjunctival) was subsequently supported by several studies. Previous studies have reported widely varying rates of infection in newborns, with estimates ranging from 4 to 79% among days old infants born to mothers testing positive for HPV during pregnancy. More recent studies reported that perinatal transmission (oral and/or genital and/or conjunctival) is between 4-22%.
Most cases of vertical transmission may occur at delivery through direct contact of the foetus and maternal infected cells during vaginal delivery or at caesarean section following early membrane rupture. Transmission in utero through semen or ascending infection from mother’s genital tract is also possible. Peri-conceptional transmission could occur since HPV DNA has been detected in 8-64% of the seminal fluid and spermatozoa. Moreover, HPV DNA has been detected in the endometrium and ovaries. Transplacental transmission has also been supported as HPV DNA is detected in amniotic fluid with detection rates varying between 15-65%. HPV DNA has also been found in placental cells and in cord blood. The detection rate of HPV DNA in trophoblastic cells varies from 0 to 60% and between 0-13% in cord blood cells. Recently, HPV DNA has been detected in breast milk with a rate varying between 2-8%. This suggests that HPV could be transmitted vertically to neonates through breastfeeding. Finally, horizontal transmission just after delivery can occur via digital contacts.
This suggests that HPV could be transmitted vertically to neonates through several modes of transmission.