Risk factors for placental human papillomavirus infection

Placental human papillomavirus infections and adverse pregnancy outcomes

INTRODUCTION

Knowledge on prevalence and association of human papillomavirus (HPV) in third trimester placentae and adverse pregnancy outcomes is limited. We investigated the prevalence of placental HPV at delivery, explored urine HPV characteristics associated with placental HPV and whether placental HPV increased the risk adverse pregnancy outcomes.

METHODS

Pregnant women were enrolled in the Scandinavian PreventADALL mother-child cohort study at midgestation. Human papillomavirus genotyping was performed on placental biopsies collected at delivery (n = 587) and first-void urine at midgestation and delivery (n = 556). Maternal characteristics were collected by questionnaires at gestational week 18 and 34. Adverse pregnancy outcomes were registered from chart data including hypertensive disorders of pregnancy, gestational diabetes mellitus and newborns small for gestational age. Uni- and multivariable regression models were used to investigate associations.

RESULTS

Placental HPV was detected in 18/587 (3 %). Twenty-eight genotypes were identified among the 214/556 (38 %) with midgestational urine HPV. Seventeen of the 18 women with placental HPV were midgestational HPV positive with 89 % genotype concordance. Midgestational high-risk-(HR)-HPV and high viral loads of Any- or HR-HPV were associated with placental HPV. Persisting HPV infection from midgestation to delivery was not associated with placental HPV. Adverse pregnancy outcomes were seen in 2/556 (0.4 %) of women with placental HPV.

DISCUSSION

In this general cohort of pregnant women, the prevalence of placental HPV was 3 %, and midgestational urinary HPV 38 %. High HPV viral load increased the risk for placental HPV infections. We observed no increased risk for adverse pregnancy outcomes in women with placental HPV.

Association between Human Papillomavirus 16 Viral Load in Pregnancy and Preterm Birth

Recent evidence shows increased preterm birth risk with human papillomavirus-16 (HPV16) infection during pregnancy. This study aimed to measure the association between HPV16 viral load during pregnancy and preterm birth. We used data from participants in the HERITAGE study. The Linear Array assay was used for HPV DNA testing on vaginal samples collected during the first and third trimesters of pregnancy. The HPV16 viral load was measured with a real-time polymerase chain reaction. We used logistic regression to measure the associations between HPV16 viral load during pregnancy and preterm birth (defined as birth before 37 weeks of gestation). The adjusted odd ratios (aORs) and the 95% confidence intervals [CIs] were estimated with inverse probability treatment weighting of the propensity score. This study included 48 participants who tested positive for HPV16 during the first trimester of pregnancy. The aOR for the association between first-trimester HPV16 viral load (higher viral load categorized with a cutoff of 0.5 copy/cell) was 13.04 [95% CI: 1.58-107.57]). Similar associations were found using different cutoffs for the categorization of viral load during the first and third trimesters. Our findings suggest a strong association between a high HPV16 viral load during pregnancy and preterm birth, demonstrating a biological gradient that reinforces the biological plausibility of a causal association.

Human Papillomavirus Concordance Between Parents and Their Newborn Offspring: Results From the Finnish Family Human Papillomavirus Study

BACKGROUND

The knowledge on vertical human papillomavirus (HPV) transmission is limited. We aimed to determine whether HPV transmission from parents to their offspring occurs before or during birth.

METHODS

Altogether, 321 mothers, 134 fathers, and their 321 newborn offspring from the Finnish Family HPV study cohort were included. Parents' genital and oral brush samples and semen samples were collected for HPV testing at baseline (36 weeks of pregnancy). Oral, genital, and umbilical samples from the newborn and placenta samples were collected for HPV testing immediately after delivery. HPV risk for the newborn was calculated from the mother's and father's HPV status by using logistic regression analyses.

RESULTS

Concordances between mothers' and their newborns' HPV genotype at any site were statistically significant with HPV-6, -16, -18, -31, and -56; odds ratios (ORs) ranged from 3.41 (95% confidence interval [CI], 1.80-6.48) for HPV-16 to 634 (95% CI, 28.5-14 087) for HPV-31. Father-newborn HPV concordance was statistically significant with HPV-6 and HPV-31 (ORs, 4.89 [95% CI, 1.09-21.9] and 65.0 [95% CI, 2.92-1448], respectively).

CONCLUSIONS

The genotype-specific HPV concordance between parents and their newborn is suggestive for vertical HPV transmission. However, transmission from the father to the newborn remains more uncertain.