The authors explained that there were conflicting results in previous studies exploring whether HPV can be vertically or horizontally transmitted from mother to child.

Dr. Xavier Castellsague from Institut Catala d’Oncologia, Barcelona, Spain and colleagues assessed the perinatal transmission and persistence of HPV types in 143 pregnant women, 66 of whom (46.2%) tested positive for HPV-DNA during pregnancy. HPV 16 singly or in combination with other types was the most frequently detected type.

The overall prevalence of HPV in infants during a mean follow-up of 14 months was 18.2%, and their most frequently detected type was also HPV 16.

HPV detected at the postpartum visit in the mother was a stronger determinant of HPV infection in the child than HPV detected during pregnancy, the investigators say, suggesting that horizontal mother-to-child transmission may play a more important role than vertical transmission in determining HPV DNA detection in children.

The investigators also found that HPV persistence is rare in infants. Eighteen of the 26 children that tested positive at some point had at least two consecutive tests; 15 of these infants were negative on the second test.

Regarding the possibility of horizontal mother-to-child transmission, the investigators comment: It remains to be seen whether this alternative mode of HPV transmission and acquisition may have an impact in several areas, including vaccination strategies, epidemiological studies, and the clinical management of children with HPV-associated diseases.