Human papillomavirus vaccinations' association to childbirth rates.

Prophylactic HPV vaccines are effective against cervical cancer and its precursors, but data on their impact on fertility and pregnancy are limited. This registry-based study examined the association between HPV vaccination and childbirth rates. Study population comprised 6200 HPV- and 1667 hepatitis B-virus (HBV) vaccinated women born in 1992-1993 and an age- and community-aligned cohort of 19,473 unvaccinated women born in 1990-1991. Nearly half of the HPV-vaccinated women participated in a cervical screening trial between ages 22 and 28. Childbirth numbers and rates per 10,000 person-years with 95% confidence interval (CI) were compared across the groups. The mean age at first childbirth ranged between 22.9 and 23.4 years among the vaccinated and unvaccinated women. At the age of 28, the cumulative proportion of all childbirths among HPV-vaccinated and screened cohorts was 2277 (36.7%), among HBV-vaccinated 781 (46.9%) and among unvaccinated reference cohorts 8997 (46.2%). Childbirth rates per 10,000 person years were 306 (95% CI 294-319), 390 (95% CI 364-419) and 385 (95% CI 377-393), respectively. HPV-vaccinated and screened women had lower childbirth rates compared to unvaccinated women at young age, possibly due to sexual counseling that HPV-vaccinated participants got in an overlapping cervical screening trial conducted between ages 22 and 28. This may have postponed their family planning to later ages.