Transmission of carcinogenic human papillomavirus types from mother to child: a meta-analysis of published studies.

Currently, human papillomavirus (HPV) research focuses on HPV infection in adults and sexual transmission. Data on HPV infection in children are slowly becoming available. It is a matter of debate whether mother-to-child transmission of HPV is an important infection route and whether children born to HPV-positive mothers are at a higher risk of HPV infection compared with children born to HPV-negative mothers. The objective of this meta-analysis is to summarize the published literature on the extent to which genital HPV infection is vertically transmitted from mother to child. Medline, Web of Science, and CINAHL were searched for eligible reports published before January 2011. Differences in the risk of HPV infection between newborns from HPV-positive and HPV-negative mothers were pooled using a random-effects model. Twenty eligible studies, including 3128 women/children pairs, fulfilled the selection criteria. High heterogeneity could be found (I=96%). The overall estimated risk difference was 33% (95% confidence interval: 22-44%). On restricting to high-risk HPV-positive mothers only (n=4; women=231), the difference in risk was 45% (95% confidence interval: 33-56%). The heterogeneity was found to be low (I=15%). This meta-analysis indicates a significantly higher risk for children born to HPV-positive mothers to become HPV positive themselves. Plausible explanations include vertical transmission of HPV during pregnancy and/or birth or a higher infection rate during early nursing from mother to child. More research is required to gain an insight into the precise mode of transmission and the clinical effects of infection on the child.