High-risk human papillomavirus detection and related risk factors among pregnant and nonpregnant women in Mexico.

BACKGROUND Significant differences in human papillomavirus (HPV) prevalence between pregnant and nonpregnant women have been reported. Some studies suggest that physiological processes during pregnancy modify the host-immune response, increasing detectability of high-risk HPV infection as a result of viral reactivation. It remains uncertain, however, whether pregnancy has an effect on HPV DNA positivity as a result of a general lack of data and based on contradictory results found in previous epidemiologic studies. We conducted an epidemiologic study to identify differences in the prevalence of HPV infection between pregnant and nonpregnant women in Mexico. We also investigated the relationship of HPV DNA positivity with socioeconomic, gynecologic, and obstetric risk factors. METHODOLOGY We screened pregnant and age-matched nonpregnant women for high-risk HPV infection. The study population was clients of the family medicine healthcare services of the Mexican Institute of Social Security in Cuernavaca, Morelos, Mexico. A total of 274 pregnant and 1060 nonpregnant study participants were screened for the presence of high-risk HPV DNA in self-collected specimens by the Hybrid Capture 2 test (HC2; Digene Corp., Gaithersburg, MD). RESULTS High-risk HPV DNA was detected in 37.2% (95% confidence interval [CI], 31-43%) of pregnant women and in 14.2% (95% CI, 12-16%) of nonpregnant women. Combining both groups for the multivariate analysis, pregnancy was associated with an increased risk for HPV infection (odds ratio, 3.5; CI, 2.7-4.9). CONCLUSIONS Our results are consistent with other studies reporting increased high-risk HPV detection rates among pregnant women. HPV-positive status in pregnant and nonpregnant women appears to be influenced by age. The decrease in HPV positivity by number of pregnancies in both currently pregnant and nonpregnant women is consistent with a possible effect of immune protection as a result of earlier HPV infections. Despite lack of information about a woman's history of sexual behavior, these data support the hypothesis that an alteration of immunologic responses during pregnancy may be associated with an increased risk of HPV acquisition or reactivation.