Objective Human papillomavirus (HPV) has been associated with adverse pregnancy outcomes but placental HPV infection has been rarely studied. The objective was to determine the proportion of HPV-positive placentas and the associated risk factors among HPV-positive women during pregnancy.

Methods We analysed data from pregnant women enrolled in HERITAGE cohort study between 2010 and 2016 with positive vaginal HPV infection during the first trimester of pregnancy (n=354). Placental swabs and biopsies were collected. HPV genotyping was performed using Linear Array. The predictors of placental HPV detection were identified by generalised estimating equations models.

Results HPV was detected in 78 placentas (22.0%) (one among 96 caesarean sections and 77 among 258 vaginal deliveries). Overall, 91% of HPV-positive placentas were positive for a genotype that was detected in vaginal samples during pregnancy. Among women who delivered vaginally, abnormal cytology (adjusted OR (aOR) 1.78 (95% CI 1.02 to 3.10)), other genitourinary infection (aOR 2.41 (95% CI 1.31 to 4.44)), presence of multiple HPV genotypes in the first trimester (aOR 2.69 (95% CI 1.76 to 4.12)) and persistence of high-risk HPV infections during pregnancy (HPV-16/18: aOR 3.94 (95% CI 2.06 to 7.55) and other than HPV-16/18: aOR 2.06 (95% CI 1.05 to 4.02)) were independently associated with placental HPV.

Conclusions HPV was frequently detected in the placenta of women who delivered vaginally and may be associated with host immune response characteristics.