Infertility and the vaginal microbiome

Healthy women have higher levels of protective lactobacilli in their vaginal microbiome than women with infertility, according to a recent cross-sectional study conducted in India by Babu et al. The study was undertaken to investigate the role of bacteria in the vaginal microbiome and the incidence of asymptomatic vaginitis and bacterial vaginosis (BV) in relation to infertility.

The researchers enrolled 200 non-pregnant women between 18 and 45 years of age who presented to Sri Lakshmi Narayana Medical College and Hospital between June 1, 2015 and December 31, 2015. Group 1 (N=84) served as a control group and was comprised of healthy women with regular menstrual cycles and no gynecologic disorders. Group 2 (N=116) consisted of women with infertility issues. Each woman completed a questionnaire and underwent a gynecologic examination. In addition, 2 high vaginal swabs were obtained from each subject (from the posterior vaginal fornix and the external orifice of the uterine cervix) and were screened for vaginal microbiota and asymptomatic vaginosis.

More Lactobacilli Found in Healthy Women

Women in the control group were found to have a higher percentage of protective lactobacilli (27.8%) compared with women in Group 2 (3.5%). The researchers wrote that “The normal vaginal ecosystem is maintained by lactobacilli that are believed to play a crucial role in producing lactic acid and other substances that inhibit the growth of pathogens and other opportunistic bacteria.”

The women with infertility had a varied microflora, with increased levels of Candida, enterococci, and Gram-negative bacilli such as E. coli. Other research has found this array of bacteria to be associated with BV, which is characterized as a disruption of normal vaginal microflora that occurs when lactobacilli are replaced by Gram-negative and Gram-positive anaerobic bacteria. As a result, the pH in the vagina is altered, which can then lead to vaginitis. The cause of BV is unknown and is likely multifactorial. In turn, vaginitis is often not detected or treated, leading to upper reproductive tract infections and potential infertility.

A third (27.6%) of the women with infertility were found to have asymptomatic vaginosis and a vaginal bacteria profile that has been associated with BV. Asymptomatic vaginosis was more prevalent among women with primary infertility versus secondary infertility, and in both healthy women and those with infertility asymptomatic vaginosis was most commonly found in women between 31 and 35 years of age. Educated women and working women were more likely to have asymptomatic vaginosis than housewives, which the researchers speculated was related to the improved access to care for the latter groups of women.

The researchers called for continuing analysis of factors such as stress that may increase the susceptibility to BV infection, as well as how the menstrual cycle, concomitant infections, contraceptive use, and vaginal cleansing habits prompt changes in the vaginal ecosystem. They also noted a need for more data on diverse patient groups and geographic settings to identify normal variations in vaginal flora patterns.

Routine Screening Recommended

Given that the vaginal microbiome of adult women is a changing ecosystem, the researchers recommended regular screening of the vaginal flora in all women, but especially those of reproductive age, to better understand the causes, treatment, and prevention of infertility problems.