Background: Human Papillomavirus (HPV) is the most frequent sexually transmitted virus. Its prevalence in third trimester and at term pregnancy differs worldwide. Gestation may favor HPV infection as cervical transformation zone is more exposed during pregnancy, and the high level of hormones have been shown to increase viral replication. HPV detection in pregnancy is important to study, as it represents a special immunological state.
Methods: Women with pregnancies at term, who attended for delivery to 3 social security hospitals from Merida, Mexico were included in this research. All participants signed informed consent. HPV PCR detection was performed in cervicovaginal samples; specific primers for HPV16, 18, 58 and 6/11 types were used for genotyping HPV positive samples. Follow-up HPV testing, cytology and colposcopy were performed 5-12 months after delivery.
Results: 794 pregnant women at term were tested for HPV, 83 resulted positive (10.7%). From these, 81 samples were genotyped resulting: 16% HPV58; 11% HPV16; 5% HPV18; 6% HPV6/11. Follow-up testing was performed to 41 out of 83 originally positive women; from these 60.7% resulted negative and therefore cleared the infection. From the remaining follow-up positive samples 11/15 were included in genotyping, which allowed to determine persistence of the same HPV type in four, and reinfection with a different type in three. Other genotypes not directly tested may have persisted in five HPV positive non-typifiable samples. From the 25 women who attended for colposcopy and cytology, two had CINII lesions.
Conclusions: This is the largest report of HPV in pregnant women from Mexico. The prevalence observed is lower than in other reports, and referred risky behaviors were low. HPV58 was the most frequently found; this genotype is also of importance in Asia. High-risk genotypes generally cleared spontaneously after the postpartum. Reinfection and persistence, although infrequent, should not be disregarded.