Vaginal washing behaviour and fecundability among Kenyan women in a prospective preconception cohort.

Vaginal washing was associated with a lower per-menstrual cycle probability of pregnancy among Kenyan women planning pregnancies. Vaginal washing has no known health benefits, and cessation may improve women’s likelihood of conceiving.

Among Kenyan women, recent vaginal washing was associated with a 29% lower per-menstrual cycle probability of pregnancy. Compared to those reporting no vaginal washing, vaginal washing with soap and water was associated with a 78% lower fecundability. Strengths include the prospective design, monthly ascertainment of vaginal washing, and inclusion of the first menstrual cycle at-risk for pregnancy for most participants. First, data on frequency, timing in relation to intercourse, and reasons for vaginal washing were not collected, so we were unable to assess these characteristics. Second, sexual frequency was not collected for a biologically-confirmed fertile window, which may contribute to residual confounding. Lastly, we were unable to assess mediation of the association between vaginal washing and fecundability by the vaginal microbiota. Our results are similar to the only other study of vaginal washing and fecundability we are aware of. 11 In a retrospective cohort study of vaginal douching among 840 women in King County, WA, vaginal douching >2 times/year prior to pregnancy was associated with a 31% lower fecundability compared to never/rare vaginal douching. Vaginal washing may reduce the presence or concentration of optimal Lactobacillus species and promote ascension of BV-associated bacteria to the upper reproductive tract causing sub-clinical or clinical PID. 7 , 8 , 20 – 22 There could also be an inflammatory response to vaginal washing independent of microbiota, as well as effects on cervical mucus. Whether associations between vaginal washing and adverse reproductive outcomes are causal versus due to a BV episode that precipitated the vaginal washing is debated. 9 , 23 , 24 We previously reported associations between recent and persistent BV and lower fecundability in this cohort. 13 Our current analysis assessing vaginal washing had similar results in adjusted models with or without BV. Due to the timing of sample collection visits and monthly assessment of vaginal washing behavior, we are unable to employ marginal structural models to assess mediation of the association between vaginal washing and lower fecundability by BV. A study addressing this question would need to measure both vaginal washing and BV at more than one point during each menstrual cycle.

Women in the Microbiota and Preterm Birth study, which enrolled women in Nairobi and Mombasa, Kenya between April 18, 2017 and March 18, 2020, were eligible for this fecundability analysis. 12 The parent study included HIV-seronegative women who were ≤45 years old, were non-contracepting (other than condoms for STI prevention), reported a menstrual period in the prior three months (or recently discontinued hormonal contraception), and were planning to become pregnant in the next six months. Women were excluded if they were not at risk for pregnancy including having a depot medroxyprogesterone acetate (DMPA) injection within three months, were at increased risk for preterm birth (ex: autoimmune diseases), used antibiotics in the last four weeks (common exclusion criterion for vaginal microbiota studies), or previously sought care for infertility. For this fecundability analysis, we excluded participants who did not contribute ≥1 menstrual cycles, those with history of PID treated in hospital, ectopic pregnancy, polycystic ovary syndrome, or endometriosis, and those trying to conceive for >3 menstrual cycles prior to enrollment ( eFigure 1 ). 13 , 14 At enrollment, participants completed an interview including socio-behavioral characteristics and medical history including first day of last menstrual period (LMP) and how long they had been non-contracepting and attempting pregnancy, and underwent a pelvic examination with vaginal swab collection. 12 At monthly preconception visits, participants underwent urine pregnancy testing, self-collected vaginal swabs, and completed an interview reporting sexual and vaginal washing behavior and first day of LMP. Participants were asked “Do you use anything to clean inside your vagina?” (no/yes). If “yes”, they were asked “In the four weeks prior to today, which of the following did you use to clean inside of your vagina?” including water only, soap and water, antiseptic, detergent, and other (specify). Most participants were eligible for up to six monthly preconception visits; those discontinuing DMPA <6 months before enrollment were eligible for up to 9 months. 15 Participants with genital symptoms were assessed and treated per Kenyan syndromic management guidelines. 16 Enrollment vaginal samples were tested for Neisseria gonorrhoeae, Chlamydia trachomatis , and Trichomonas vaginalis (Aptima Combo-2 CT/NG Detection System, Aptima Trichomonas vaginalis assay; Hologic Incorporated). Directed treatment was provided for STIs detected at enrollment. Vaginal samples from all visits were assessed for BV using Nugent criteria. 17 Two time-varying measures of vaginal washing were considered: 1) any vaginal washing in the last four weeks (no/yes), and 2) type of vaginal washing in the last four weeks (none, water only, soap and water). Two cycles were characterized by antiseptic use and were included with soap and water. Three cycles with an “other” type of vaginal washing were included with either water only or soap and water based on review of the substances specified. For each participant, number of menstrual cycles to first incident pregnancy was calculated using reported first days of LMPs and monthly urine pregnancy test results. 13 In July 2018, a question was added to the monthly interview for report of additional first days of LMPs (“interim menstrual cycles”) for women who missed preconception visits (n=82 cycles reported). One-hundred thirty participants had visits prior to July 2018 and in these cases “interim menstrual cycles” were derived (n=41 cycles), as previously described. 13 Participants were censored during follow-up for biomedical infertility treatment (n=3), not conceiving during follow-up (n=73), withdrawal or loss to follow-up (n=49), and at the onset of the COVID-19 pandemic (n=35). We used discrete time proportional probabilities models to generate fecundability ratios (FR) and 95% confidence intervals (95% CI) estimating the association between vaginal washing and fecundability. 14 , 18 For participants with prior conception attempt time, we utilized delayed entry to enter participants into the analysis at their current menstrual cycle of trying to reduce left truncation bias. Based on existing literature, knowledge of the study population, and consideration of causal relationships, maternal age (years: <25, 25–29, 30–34, 35–39, 40–45), frequency of unprotected intercourse in the prior four weeks (none, 1–4, 5–8, ≥9), and study site were included a priori in multivariable models. 1 , 19 In a second adjusted model, we included BV (Nugent score ≥7) at the visit prior, as women may have engaged in vaginal washing because of BV. 13 For 123 derived or reported “interim menstrual cycles” (8.9% of cycles) and for rare data missingness for attended visits (0.03% of cycles), missing vaginal washing and unprotected intercourse data were imputed using data from the last visit carried forward. First, we excluded those with potential sub-fecundity ( N. gonorrhoeae, C. trachomatis, T. vaginalis or PID at enrollment, any history of PID diagnosis or treatment for N. gonorrhoeae, C. trachomatis, T. vaginalis , or syphilis; self-report of fibroids or unknown uterine abnormality; DMPA use within six months of enrollment, HIV-seropositive partner). Second, we excluded derived and reported menstrual cycles. Third, we included women reporting ≤6 menstrual cycles of pre-enrollment conception attempt time. The Kenyatta National Hospital-University of Nairobi and University of Washington ethics committees approved this study. Participants provided written informed consent.

The 458 participants were a median of 29 years old (IQR 25–34) and most reported no prior conception attempt time (80.1%, n=367) ( Table 1 ). There were 255 pregnancies across 1,376 menstrual cycles. Twenty-six percent (359 of 1376) of cycles were exposed to vaginal washing ( Table 2 ), with water accounting for 20.9% (287 of 1376) of cycles and soap and water 5.2% (42 of 1376) of cycles. After adjustment for age, frequency of unprotected intercourse, and study site, vaginal washing in the prior four weeks was associated with a 29% lower fecundability (adjusted FR (aFR) 0.71, 95% CI 0.53,0.94), which was similar after further adjustment for BV (aFR 0.71, 95% CI 0.54, 0.95) ( Table 2 ). Compared to no vaginal washing, vaginal washing with water only was associated with a 17% lower fecundability (aFR 0.83, 95% CI 0.62, 1.10) and vaginal washing with soap and water was associated with a 78% lower fecundability (aFR 0.22, 95% CI 0.07, 0.71). Results were similar for sensitivity analyses excluding women with potential sub-fecundity, excluding derived and reported cycles, and including participants with up to 6 cycles of pre-enrollment conception attempt time ( eTable 1 ).

Intravaginal washing practices include cleansing with water or products such as vinegar, soaps, or douching agents. 1 Many women globally engage in vaginal washing to improve hygiene, prevent pregnancy, prevent or treat vaginal infections, or promote sexual pleasure. 1 – 7 Vaginal washing is associated with increased risk of bacterial vaginosis (BV), sexually transmitted infections (STI), human immunodeficiency virus (HIV), and pelvic inflammatory disease (PID). 8 – 10 Only one prior study has assessed the association between vaginal douching and fecundability, finding lower fecundability among those engaging in vaginal douching. 11 Our objective was to prospectively assess the association between vaginal washing and fecundability in Kenyan women planning pregnancy.

Among Kenyan women attempting pregnancy, there was an association between recent vaginal washing and lower fecundability that was strongest among those using soap and water. Vaginal washing cessation may improve women’s likelihood of conceiving.