Cultivable vaginal Lactobacillus not linked to fecundability

Among women attempting nonmedically assisted conception, cultivable vaginal Lactobacillus does not appear to be associated with the probability to conceive within one menstrual cycle, a study reports.

The study included 458 women from Nairobi and Mombasa in Kenya who had been attempting to conceive for ≤3 months. All women reported the first day of their last menstrual period and recent sexual behaviour, underwent pregnancy testing, and provided vaginal specimen samples for Lactobacillus culture and Gram stain at ≤6 monthly preconception visits.

A total of 1,376 menstrual cycles were recorded. At baseline, 299 women (65.3 percent) had cultivable Lactobacillus, 217 (47.4 percent) had cultivable hydrogen peroxide-producing Lactobacillus, and 296 (64.6 percent) had Lactobacillus detected on Gram stain.

In unadjusted proportional probabilities models, cultivable Lactobacillus at the prior visit showed no association with fecundability (fecundability ratio [FR], 0.92, 95 percent confidence interval [CI], 0.73–1.16). This held true after controlling for potential confounders, including age, frequency of condomless sex, and study site (adjusted FR, 0.92, 95 percent CI, 0.72–1.18).

However, Lactobacillus morphotypes on Gram stain at the visit prior was associated with modestly higher fecundability (adjusted FR, 1.18, 95 percent CI, 0.92–1.51).

The finding on Gram stain suggests that the relationship between vaginal Lactobacillus and fecundity may be species-specific.