Incident cervical infections with high- and low-risk human papillomavirus (HPV) infections among mothers in the prospective Finnish Family HPV Study

Background: The knowledge on type specificity and factors that increase or decrease the risk of incident HPV-infections is important to better understand the dynamics of HPV-infections. Methods: A series of 329 pregnant women were enrolled in Finnish Family HPV Study at 3(rd) trimester of pregnancy and followed-up for 6 years, during which 203 baseline HPV-negative women acquired incident HPV infection. Incidence times and incidence rates (IR) were calculated for 24 low-and high-risk HPV-types detected by Multiplex-HPV-genotyping at each visit. Poison regression was used to estimate predictors of incident HPV infections of species 7 and 9 HPV-genotypes. Results: HPV16 was the most frequent (47.8%) incident genotype followed by multiple-type infections (25.1%), and single infection with HPV18, 70, 6 and 45. Actuarial mean times to incident event were longest for HPV31 (34.5 months) and HPV45 (32.8 months), while crude mean times were longest for HPV56 (42.4 months) and HPV16 (23.1 months). Actuarial IR was highest for HPV16 and multiple-type infections. Independent protective factors against incident infections were 1) > 2 life-time sexual partners (p = 0.014), 2) later initiation of oral contraceptives (age > 20 years) (p = 0.017) and 3) pregnancy at FU visit (p = 0.0001). Conclusions: Among newly delivered mothers, higher number of life-time sexual partners, initiation of OC use after age 20 and becoming pregnant during FU decreased the risk for incident species 7/9 HPV infections.