Association between bacterial vaginosis and fecundability in Kenyan women planning pregnancies: a prospective preconception cohort study

Testing on bacterial vaginosis in a subfertile population and time to pregnancy: a prospective cohort study

PURPOSE

This study aimed to investigate the influence of bacterial vaginosis on time to pregnancy in subfertile couples.

METHODS

Couples attending a teaching hospital in the Netherlands having an initial fertility assessment (IFA) between July 2019 and June 2022 were included in this prospective study, with follow-up of pregnancies until June 2023. Vaginal samples at IFA were analyzed on pH, qPCR BV, and 16S rRNA gene microbiome analysis of V1-V2 region. Main outcome measures were time from initial fertility assessment to ongoing pregnancy at 12 weeks and live birth, analyzed by Kaplan-Meier and Cox regression with adjustment for potential confounders.

RESULTS

At IFA, 27% of 163 included participants tested positive for BV. BV status had no influence on time to ongoing pregnancy (HR 0.98, 0.60-1.61, aHR 0.97, 0.58-1.62). In persons with unexplained subfertility, positive BV status had a tendency of longer time to pregnancy. When persons had an indication for fertility treatment, positive BV status (HR 0.21, 0.05-0.88, aHR 0.19, 0.04-0.85) and microbiome community state type III and type IV had significant longer time to pregnancy.

CONCLUSION

This study indicates that BV may have a potential negative impact on time to live birth pregnancy in subfertile persons with an indication for fertility treatment. This study did not find an association between BV and time to live birth pregnancy in a general group of subfertile couples or in unexplained subfertility. More research should be done in persons with unexplained subfertility and if treatment improves time to pregnancy.

Longitudinal assessment of bacterial vaginosis prior to and during incident pregnancy: an observational study in Kenyan adolescent girls and young women

OBJECTIVE

To determine bacterial vaginosis (BV) status at multiple time points among adolescent girls and young women (AGYW) and assess the impact of pregnancy on their BV status.

DESIGN

Longitudinal cohort study.

SETTING

Thika, Kenya.

PARTICIPANTS

AGYW aged 16-20 years enrolled prior to first sex or reporting only a single lifetime partner.

MAIN OUTCOME MEASURES

The primary outcome was relative risk (RR) of BV during pregnancy compared with before pregnancy by analysing longitudinal trends in BV over time. BV risk was estimated using Poisson regression models.

RESULTS

A total of 121 AGYW became pregnant in the parent cohort and had BV results before, during or after pregnancy. Point prevalence of BV was 11.0% at visits >12 months pre-pregnancy, 13.0% at 3-12 months pre-pregnancy, 22.1% at <3 months pre-pregnancy and 13.4% during pregnancy. Compared with visits during pregnancy, RR of BV was 1.65 (95% CI: 1.00 to 2.71; p=0.05) at visits <3 months pre-pregnancy, 0.97 (95% CI: 0.62 to 1.52; p=0.90) at visits 3-12 months pre-pregnancy and 0.82 (95% CI: 0.44 to 1.53; p=0.53) at visits 12 months pre-pregnancy. An adjusted analysis including age, income, residence, date of first sex, recent sexual activity and positive sexually transmitted infection test resulted in small changes in risk estimates, with adjusted RR of BV of 1.66 (95% CI: 1.04 to 2.67; p=0.04) at visits <3 months pre-pregnancy compared with visits during pregnancy.

CONCLUSIONS

BV risk during pregnancy was lower than during the immediate pre-pregnancy period. Hormonal changes in pregnancy may reduce BV.

A prospective preconception cohort study of the association between Mycoplasma genitalium and fecundability in Kenyan women trying to conceive

STUDY QUESTION

Is Mycoplasma genitalium-infection associated with reduced fecundability?

SUMMARY ANSWER

Preconception M. genitalium-infection was associated with 27% lower fecundability though confidence intervals were wide, and the association between M. genitalium and fecundability may be dependent on concurrent bacterial vaginosis (BV).

WHAT IS KNOWN ALREADY

M. genitalium has been associated with cervicitis, pelvic inflammatory disease, infertility, and preterm birth, but the extent to which M. genitalium is causally related to adverse reproductive sequelae in women is debated.

STUDY DESIGN, SIZE, DURATION

Kenyan women enrolled in a prospective preconception cohort provided vaginal fluid specimens and underwent monthly pregnancy testing. Stored samples from 407 women who had been trying to conceive for ≤6 months were tested for M. genitalium using a nucleic acid amplification test.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data on first day of last menstrual period, sexual behavior, pregnancy status, and vaginal specimens were collected at monthly preconception visits. The association between M. genitalium detected at the visit prior to each pregnancy test and fecundability was estimated using discrete time proportional probabilities models. Secondary analyses explored the influence of concurrent BV on the association between M. genitalium and fecundability.

MAIN RESULTS AND THE ROLE OF CHANCE

The 407 participants experienced 1220 menstrual cycles and 213 pregnancies. The prevalence of M. genitalium at enrollment was 7.7%. After adjustment for age, frequency of condomless sex in the last 4 weeks, and study site, M. genitalium was associated with a 27% lower fecundability, but confidence intervals were wide (adjusted fecundability ratio (aFR) 0.73, 95% CI 0.44, 1.23). In secondary analyses, when compared to cycles without M. genitalium or BV at the visit prior, women with both M. genitalium and BV at the visit prior had a 51% lower fecundability (aFR = 0.49, 95% CI 0.22, 1.09) whereas there was no association of M. genitalium alone (aFR = 0.98 (95% CI 0.54, 1.76)), and a smaller reduction in fecundability for women with BV only (aFR = 0.80 (95% CI 0.60, 1.07)).

LIMITATIONS, REASONS FOR CAUTION

Results should be interpreted cautiously given the relatively low prevalence of M. genitalium and wide confidence intervals.

WIDER IMPLICATIONS OF THE FINDINGS

In this cohort of Kenyan women trying to conceive, the association between M. genitalium and fecundability was influenced by concurrent BV status, suggesting there may be a synergistic effect of M. genitalium and BV on fecundability.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by a National Institutes of Health grant (NICHD R01 HD087346-RSM). R.S.M. received additional support for mentoring (NICHD K24 HD88229). E.M.L. was supported by pre- and post-doctoral fellowships (NIAID T32 AI07140, NICHD F32 HD100202). Data collection and management were completed using REDCap electronic data capture tools hosted at the University of Washington's Institute of Translational Health Science supported by grants from NCATS/NIH (UL1 TR002319). The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. R.S.M. receives research funding, paid to the University of Washington, from Hologic Corporation and consulting fees from Lupin Pharmaceuticals. L.E.M. receives research funding and material for research studies, paid to the University of Washington, from Hologic Corporation and Nabriva Therapeutics, travel support from Hologic, and consulting fees from Health Advances. E.M.L.'s contributions to this study primarily occurred while affiliated with the University of Washington; at the time of submission, E.M.L. was an employee of and holds stock or stock grants for AbbVie, Inc. The other authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Low prevalence of bacterial vaginosis in Kenyan adolescent girls and rapid incidence after first sex

BACKGROUND

Bacterial vaginosis is a risk factor for sexually transmitted infections, including HIV. Adult African women have a high prevalence of bacterial vaginosis, but it is not known when first bacterial vaginosis occurs.

OBJECTIVE

This study aimed to describe bacterial vaginosis in younger African women, before and after first sex, and to determine the incidence of bacterial vaginosis and significant correlates of bacterial vaginosis incidence and recurrence.

STUDY DESIGN

In a prospective observational cohort study enrolling adolescents with limited sexual experience, young women aged 16 to 21 years were recruited in Thika, Kenya. Eligible participants were HIV and herpes simplex virus 2 seronegative and reported 0 or 1 lifetime sexual partner. The Nugent score was determined at quarterly visits from vaginal Gram stains. The trends in bacterial vaginosis were described over time; hazard ratios were calculated using Cox regression, and relative risk of bacterial vaginosis was estimated using generalized estimating equations and Poisson regression.

RESULTS

A total of 400 participants with a median age of 18.6 years (interquartile range, 16-21) were enrolled. Of note, 322 participants (80.5%) reported no history of sex, whereas 78 participants (19.5%) reported sex with 1 partner. At enrollment, bacterial vaginosis (Nugent score of ≥7) was uncommon (21/375 [5.6%]). Overall, 144 participants had bacterial vaginosis at least once, for an incidence rate of 16.5 cases per 100 person-years. Before first sex, bacterial vaginosis was present at 2.8% of visits, compared with 13.7% of visits after first sex. An adjusted model of bacterial vaginosis incidence observed that first sex was associated with more than a 2-fold increased bacterial vaginosis risk (adjusted hazard ratio, 2.44; 95% confidence interval, 1.25-4.76; P=.009). Chlamydia diagnosis (adjusted hazard ratio, 1.73; 95% confidence interval, 1.1-2.8; P=.02), and herpes simplex virus 2 seropositivity (adjusted hazard ratio, 2.88; 95% confidence interval, 1.17-7.09; P=.021) were both associated with incident bacterial vaginosis. A multivariate generalized estimating equation model, including all episodes of bacterial vaginosis, demonstrated risk factors, including first sex, sexually transmitted infections, urban residence, recent sex, and no income; the most important risk factor was first sex (adjusted relative risk, 1.92; 95% confidence interval, 1.12-3.31; P=.018). The probability of bacterial vaginosis increased with each subsequent episode; mean Nugent scores increased after each bacterial vaginosis episode.

CONCLUSION

Using detailed longitudinal observation, this study found that Kenyan adolescents have almost no bacterial vaginosis before first sex and that initiation of sexual activity was the strongest risk factor for both prevalent bacterial vaginosis and incident bacterial vaginosis.

Association between vaginal microbiomes and neonatal septicemia in pregnant women with preterm premature rupture of membranes based on metagenome sequencing

BACKGROUND

Preterm premature rupture of membranes (PPROM) is closely associated with pathogenic microbiomes in the female reproductive tract, and can lead to neonatal septicemia. The current study aimed to investigate potential pathogenic microbiomes associated with neonatal septicemia based on DNA metagenome sequencing.

METHODS

In this study, a total of 7 pregnant women with PPROM presenting neonatal septicemia (experimental group) and 3 pregnant women with normal newborns (control group) were enrolled. Vaginal secretions at admission and before parturition as well as placental tissues after parturition were collected for DNA metagenome sequencing using whole genome shotgun method on the Illumina NovaSeq/HiSeq platform. Raw data were processed by BioBakery workflow, and MetaPhlAn4 was implemented for qualitative and quantitative analyses of microbiome. Lactobacillus crispatus, Gardneralla vaginalis, Fannyhessea vaginae and Streptococcus suis were specifically detected from the experimental group. The two groups were compared using Student's t-tests.

RESULTS

The indexes of Chao1 (P=0.00028/P=0.00072), abundance-based coverage estimator (ACE, P=0.00059/P=0.00026), Shannon (P=0.036/P=0.0065) and Simpson (P=0.007/P=0.041) in the experimental group were increased at admission and before parturition as compared with the control group. Several microbiomes, such as Lactobacillus crispatus, Gardneralla vaginalis, Fannyhessea vaginae and Streptococcus suis, were specifically detected in the experimental group. Notably, Gardnerella vaginalis and Streptococcus gallolyticus were identified from the vaginal secretions and placenta tissues of women with neonatal septicemia. Moreover, nucleic acid synthesis and carbohydrate metabolism-related pathways were enriched in the experimental group.

CONCLUSION

This study enhanced the current understanding of the mechanisms underlying pathogenic microbiomes in PPROM-induced neonatal septicemia. The trial registry number is ChiCTR2300070666 (URL: https://www.chictr.org.cn/showproj.html?proj=195648).

Lactobacilli and Their Probiotic Effects in the Vagina of Reproductive Age Women

In the present narrative review, the probiotic effects of vaginal Lactobacillus spp. are described in detail, covering the importance of the differential production of lactic acid, the lactic acid D/L isoforms, the questionable in vivo effect of hydrogen peroxide, as well as bacteriocins and other core proteins produced by vaginal Lactobacillus spp. Moreover, the microbe–host interaction is explained with emphasis on the vaginal mucosa. To understand the crucial role of Lactobacillus spp. dominance in the vaginal microbiota, different dysbiotic states of the vagina are explained including bacterial vaginosis and aerobic vaginitis. Finally, this review takes on the therapeutic aspect of live lactobacilli in the context of bacterial vaginosis. Until recently, there was very low-quality evidence to suggest that any probiotic might aid in reducing vaginal infections or dysbiosis. Therefore, clinical usage or over the counter usage of probiotics was not recommended. However, recent progress has been made, moving from probiotics that are typically regulated as food supplements to so-called live biotherapeutic products that are regulated as medical drugs. Thus, recently, a phase 2b trial using a Lactobacillus crispatus strain as a therapeutic add-on to standard metronidazole showed significant reduction in the recurrence of bacterial vaginosis by 12 weeks compared to placebo. This may constitute evidence for a brighter future where the therapeutic use of lactobacilli can be harnessed to improve women’s health.

The Vaginal Microbiome in Health and Disease-What Role Do Common Intimate Hygiene Practices Play?

The vaginal microbiome is a dynamic, sensitive microenvironment. The hallmark of a 'healthy' vaginal microbiome is currently believed to be one dominated by Lactobacillus spp., which acidifies the vaginal environment and help to protect against invading pathogens. However, a 'normal' microbiome is often difficult, if not impossible, to characterise given that it varies in response to numerous variables, including pregnancy, the menstrual cycle, contraceptive use, diet, ethnicity, and stress. A Lactobacillus-depleted microbiome has been linked to a variety of adverse vaginal health outcomes, including preterm birth (PTB), bacterial vaginosis (BV), and increased risk of sexually transmitted infections. The latter two of these have also been associated with feminine intimate hygiene practices, many of which are practised without any evidence of health benefits. The most extensively studied practice is vaginal douching, which is known to cause vaginal dysbiosis, predisposing women to BV, pelvic inflammatory disease, and PTB. However, little is known of the impact that intimate hygiene practices and associated products have on the vaginal microbiome. This review aims to outline the major factors influencing the vaginal microbiome and common vaginal infections, as well as to summarise current research surrounding the impact of hygiene products and practices on the vaginal microbiome.

Association between antibiotic exposure and the risk of infertility in women of childbearing age: A case-control study

BACKGROUND

Based on self-report questionnaires, two previous epidemiological studies investigated the association between the exposure of women to antibiotics and their fertility. However, biomonitoring studies on low-dose antibiotic exposure, mainly from food and water, and its relation to the risk of infertility are missing.

METHODS

Based on a case-control study design, 302 women with infertility (144 primary infertility, 158 secondary infertility) and 302 women with normal fertility, all aged 20-49 years, were recruited from Anhui Province, China, in 2020 and 2021. A total of 41 common antibiotics and two antibiotic metabolites in urine samples were determined by liquid chromatography-triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS).

RESULTS

Twenty-eight antibiotics with detection rates from 10% to 100% in both cases (median concentration: ∼2.294 ng/mL) and controls (∼1.596 ng/mL) were included in the analysis. Logistic regression analysis revealed that after controlling for confounding factors, high concentrations of eight individual antibiotics (sulfamethoxazole, sulfaclozine, sulfamonomethoxine, penicillin G, chlorotetracycline, ofloxacin, norfloxacin, and cyadox) and four antibiotic classes (sulfonamides, tetracyclines, quinoxalines, and veterinary antibiotics) were related to a high risk of female infertility, with odds ratios (ORs) ranging from 1.30 to 2.86, except for chlorotetracycline (OR = 6.34), while another nine individual antibiotics (sulfamethazine, azithromycin, cefaclor, amoxicillin, oxytetracycline, pefloxacin, sarafloxacin, enrofloxacin, and florfenicol) and classes of chloramphenicol analogs and human antibiotics were related to a reduced risk of infertility, with ORs ranging from 0.70 to 0.20. Based on restricted cubic spline models after controlling for confounding factors, we observed that the relationship between all of the above protective antibiotics and infertility was nonlinear: A certain concentration could reduce the risk of female infertility while exceeding a safe dose could increase the risk of infertility.

CONCLUSION

These results provide preliminary evidence that the effects of antibiotics on female fertility vary based on the active ingredient and usage and imply the importance of exposure dose. Future studies are needed to verify these results by controlling for multiple confounding factors.

Adverse effect of lactobacilli-depauperate cervicovaginal microbiota on pregnancy outcomes in women undergoing frozen-thawed embryo transfer

Purpose

The cervicovaginal microbiota is essential for maintaining the health of the female reproductive tract. However, whether cervicovaginal microbiota status prior to frozen embryo transfer (FET) associates with pregnancy outcomes is largely unexplored.

Methods

Cervical mucus from 29 women who had undergone FET was collected. Microbial composition was analyzed using 16 S rRNA gene sequence to assess the correlation to the pregnancy outcomes.

Results

CST-categorized Lactobacillus was the most dominant (41.71%) in the pregnant group, while CST-IV-based and BV-related Gardnerella (34.96%) prevailed in the non-pregnant group. The average abundance of Gardnerella compared non-pregnant to pregnant women was the highest (34.96% vs. 4.22%, p = 0.0015) among other CST-IV indicator bacteria. Multivariate analysis revealed that CST-IV-related bacteria have a significantly adverse effect on ongoing pregnancy outcomes (odds ratio, 0.083; 95% confidence index, 0.012-0.589, p = 0.013*).

Conclusions

The study found that the CST-IV microbiota, with significantly increasing Gardnerella and the loss of Lactobacilli as the dominant bacteria, can potentially contribute to pregnancy failure. Therefore, dysbiotic microbiota may be a risk factor in women undergoing FET. Assessing the health of the cervicovaginal microbiota prior to FET would enable couples to make a more thoughtful decision on the timing and might improve pregnancy outcomes.

The association between the pre-pregnancy vaginal microbiome and time-to-pregnancy: a Chinese pregnancy-planning cohort study

BACKGROUND

Although sexually transmitted infections are regarded as the main cause of tubal infertility, the association between the common vaginal microbiome and female fecundability has yet to be determined. The objective of this study was to find convincing evidence relating to the impact of the vaginal bacterial structure on the fecundability of women planning pregnancy.

METHODS

We recruited women who took part in the Free Pre-pregnancy Health Examination Project from 13 June 2018 to 31 October 2018 (n = 89, phase I) and from 1 November 2018 to 30 May 2020 (n = 389, phase II). We collected pre-pregnancy vaginal swabs from each subject; then, we followed up each subject to acquire the pregnancy-planning outcome in 1 year. In phase I, 16S rRNA gene sequencing was performed to investigate the vaginal bacterial content between the pregnancy and non-pregnancy groups. These findings were verified in phase II by applying a quantitative real-time polymerase chain reaction for the measurement of the absolute abundance of specific species. Cox models were used to estimate fecundability ratios (FR) for each vaginal microbiome type.

RESULTS

In phase I, 59.6% (53/89) of women became pregnant within 1 year. The principal coordinate analysis showed that the pre-pregnancy vaginal microbial community structures of the pregnant and non-pregnant groups were significantly different (PERMANOVA test, R² = 0.025, P = 0.049). The abundance of the genus Lactobacillus in the pregnancy group was higher than that of the non-pregnant group (linear discriminant analysis effect size (LDA) > 4.0). The abundance of the genus Gardnerella in the non-pregnant group was higher than those in the pregnant group (LDA > 4.0). In phase II, female fecundability increased with higher absolute loads of Lactobacillus gasseri (quartile Q4 vs Q1, FR = 1.71, 95%CI 1.02-2.87) but decreased with higher absolute loads of Fannyhessea vaginae (Q4 vs Q1, FR = 0.62, 95%CI 0.38-1.00). Clustering analysis showed that the vaginal microbiome of type D (characterized by a higher abundance of Lactobacillus iners, a lower abundance of Lactobacillus crispatus and Lactobacillus gassri) was associated with a 55% reduction of fecundability (FR = 0.45, 95%CI 0.26-0.76) compared with type A (featuring three Lactobacillus species, low Gardnerella vaginalis and Fannyhessea vaginae abundance).

CONCLUSIONS

This cohort study demonstrated an association between the pre-pregnancy vaginal microbiome and female fecundability. A vaginal microbiome characterized by a higher abundance of L. iners and lower abundances of L. crispatus and L. gasseri appeared to be associated with a lower fecundability. Further research now needs to confirm whether manipulation of the vaginal microenvironment might improve human fecundability.

The associations between low abundance of Mycoplasma hominis and female fecundability: a pregnancy-planning cohort study

OBJECTIVE

To explore the impact of pre-pregnancy vaginal Mycoplasma hominis (M. hominis) colonization of low abundance on female fecundability.

METHODS

In total, 89 females participating in a pre-pregnancy health examination program were included, and their pregnancy outcomes were followed up for 1 year. Vaginal swabs were collected, 16S rRNA genes were sequenced, and M. hominis colonization was confirmed by qPCR. Cox models were used to estimate the fecundability odds ratio (FOR) for women with M. hominis.

RESULTS

The prevalence of M. hominis was 22.47% (20/89), and the abundance was relatively low (the cycle thresholds of the qPCR were all more than 25). In terms of the vaginal microbiome, the Simpson index of the positive group was significantly lower than that of the negative group (P = 0.003), which means that the microbiome diversity appeared to increase with M. hominis positivity. The relative abundance of M. hominis was negatively correlated with Lactobacillus crispatus (rho = - 0.24, P = 0.024), but positively correlated with Gardnerella vaginalis, Atopobium vaginae and Prevotella bivia (P all < 0.05). The cumulative one-year pregnancy rate for the M. hominis positive group was lower than that in the negative group (58.96% vs 66.76%, log-rank test: P = 0.029). After controlling for potential confounders, the risk of pregnancy in the M. hominis positive group was reduced by 38% when compared with the positive group (FOR = 0.62, 95% CI: 0.42-0.93).

CONCLUSION

The vaginal colonization of M. hominis at a low level in pre-pregnant women is negatively correlated with female fecundability.

Wet Mount Microscopy of the Vaginal Milieu Does Not Predict the Outcome of Fertility Treatments: A Cross-sectional Study

OBJECTIVE

The aim of the study was to evaluate whether vaginal dysbiosis (bacterial vaginosis [BV] or moderate/severe aerobic vaginitis [AV]/desquamative inflammatory vaginitis) in women subjected to intrauterine insemination (IUI) or in vitro fertilization/intracytoplasmic sperm injection influences the rates of pregnancy.

MATERIALS AND METHODS

This is a cross-sectional study involving 392 women who underwent IUI or in vitro fertilization/intracytoplasmic sperm injection at a fertility clinic. All had a slide collected for phase contrast wet mount microscopy (WMM), which was classified according to the International Society for the Study of Vulvovaginal Disease recommendations. Correlation between flora patterns and the rate of pregnancy were evaluated.

RESULTS

There were no differences in any of the groups in terms of pregnancy rate (biochemical, clinical, at first trimester ultrasound, or live birth) after stratifying for the presence of BV, moderate or severe (ms) AV, BV and/or moderate or severe AV, cytolysis, or abnormal vaginal flora (lactobacillary grade ≥ IIb). The presence of Candida species, cocci, or bacilli morphotypes other than lactobacilli also showed no differences.

CONCLUSIONS

The vaginal flora assessment by WMM at the time of IUI or oocyte retrieval was not predictive of the success of fertility treatments.The absence of differences may be due to intrinsic limitations of WMM (i.e., identifying only bacterial morphotypes), a positive impact of the treatments in the vaginal flora or because the sperm and embryo transfer is made directly into the uterine cavity, thus overcoming any cervical or vaginal dysbiosis disadvantage. Future studies should focus on the endometrial milieu, rather than in the vaginal and/or cervical one.

Cultivable vaginal Lactobacillus is not associated with fecundability in Kenyan women attempting to conceive

OBJECTIVE

To examine the association between cultivable vaginal Lactobacillus and fecundability in Kenyan women attempting nonmedically assisted conception.

DESIGN

Prospective preconception cohort.

SETTING

Nairobi and Mombasa, Kenya.

PATIENT(S)

Women trying to conceive who reported ≤3 months of pre-enrollment conception attempt time.

INTERVENTION(S)

Cultivable Lactobacillus (primary), Lactobacillus morphotypes on Gram stain (secondary).

MAIN OUTCOME MEASURE(S)

Participants reported the first day of their last menstrual period and recent sexual behavior, underwent pregnancy testing, and provided vaginal specimen samples for Lactobacillus culture and Gram stain at ≤6 monthly preconception visits. The outcome was fecundability-the per-menstrual cycle probability of pregnancy. Associations between cultivable Lactobacillus and Lactobacillus morphotypes on Gram stain at the visit before each pregnancy test and fecundability were estimated using proportional probabilities models to generate fecundability ratios (FRs).

RESULT(S)

A total of 458 women contributed 1,376 menstrual cycles. At enrollment, 65.3% (n = 299) of participants had cultivable Lactobacillus, 47.4% (n = 217) had cultivable hydrogen peroxide producing Lactobacillus, and 64.6% (n = 296) had Lactobacillus detected on Gram stain. In unadjusted analysis, there was no association between cultivable Lactobacillus at the prior visit and fecundability (FR, 0.92; 95% CI, 0.73-1.16); results were similar after adjustment for age, frequency of condomless sex, and study site (adjusted FR, 0.92; 95% CI, 0.72-1.18). Lactobacillus on Gram stain at the visit prior was associated with modestly higher fecundability (adjusted FR, 1.18; 95% CI, 0.92-1.51).

CONCLUSION(S)

Cultivable Lactobacillus was not associated with fecundability, although Lactobacillus morphotypes detected on Gram stain were somewhat associated with increased fecundability. The relationship between vaginal Lactobacillus and fecundity may be species-specific.

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

BACKGROUND

Intravaginal washing, practised by a significant proportion of women globally, is associated with acquisition of human immunodeficiency virus (HIV), sexually transmitted infections and bacterial vaginosis (BV). A single prior study among women in the United States found that vaginal washing was associated with lower fecundability.

OBJECTIVE

To examine the association between vaginal washing and fecundability among Kenyan women.

METHODS

HIV-negative Kenyan women who were trying to conceive and reported no history of infertility care-seeking were followed prospectively for incident pregnancy for up to six months. At monthly visits, participants reported the first day of last menstrual period, sexual behaviour, vaginal washing behaviour, underwent pregnancy testing and provided vaginal swabs for detection of BV by Gram stain (Nugent score ≥7). Discrete time proportional probability models were used to estimate fecundability ratio (FR) and 95% confidence interval (CI) comparing menstrual cycles when women reported vaginal washing to menstrual cycles when no vaginal washing was reported.

RESULTS

Four hundred and fifty-eight women contributed 1,376 menstrual cycles and 255 pregnancies. At enrolment, a third (35.2%, 161 of 458) of participants reported vaginal washing with the majority using water only (73.9%, 119 of 161). 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 did not change after further adjustment for BV at the visit prior to each pregnancy test (aFR 0.71, 95% CI 0.54, 0.95).

CONCLUSIONS

Periconceptual vaginal washing may reduce fecundability. Potential mechanisms include vaginal washing-associated changes in the vaginal microbiota, inflammation, disruption of cervical mucus and effects on sperm function. Vaginal washing has no known health benefits, and cessation may improve women's likelihood of conceiving.

Antibiotics and fecundability among female pregnancy planners: a prospective cohort study

STUDY QUESTION

To what extent is female preconception antibiotic use associated with fecundability?

SUMMARY ANSWER

Preconception antibiotic use overall was not appreciably associated with fecundability.

WHAT IS KNOWN ALREADY

Antibiotics are commonly used by women and are generally thought to be safe for use during pregnancy. However, little is known about possible effects of antibiotic use on fecundability, the per-cycle probability of conception. Previous research on this question has been limited to occupational rather than therapeutic exposure.

STUDY DESIGN, SIZE, DURATION

We analyzed data from an Internet-based preconception cohort study of 9524 female pregnancy planners aged 21-45 years residing in the USA and Canada who had been attempting to conceive for six or fewer cycles at study entry. Participants enrolled between June 2013 and September 2020 and completed baseline and bimonthly follow-up questionnaires for up to 12 months or until a reported pregnancy, whichever came first. The questions pertaining to antibiotic type and indication were added to the PRESTO questionnaires in March 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We assessed antibiotic use in the previous 4 weeks at baseline and on each follow-up questionnaire. Participants provided the name of the specific antibiotic and the indication for use. Antibiotics were classified based on active ingredient (penicillins, macrolides, nitrofurantoin, nitroimidazole, cephalosporins, sulfonamides, quinolones, tetracyclines, lincosamides), and indications were classified by type of infection (respiratory, urinary tract, skin, vaginal, pelvic, and surgical). Participants reported pregnancy status on follow-up questionnaires. We used proportional probabilities regression to estimate fecundability ratios (FR), the per-cycle probability of conception comparing exposed with unexposed individuals, and 95% CI, adjusting for sociodemographics, lifestyle factors, and reproductive history.

MAIN RESULTS AND THE ROLE OF CHANCE

Overall, women who used antibiotics in the past 4 weeks at baseline had similar fecundability to those who had not used antibiotics (FR: 0.98, 95% CI: 0.89-1.07). Sulfonamides and lincosamides were associated with slightly increased fecundability (FR: 1.39, 95% CI: 0.90-2.15, and FR: 1.58 95% CI: 0.96-2.60, respectively), while macrolides were associated with slightly reduced fecundability (FR: 0.70, 95% CI: 0.47-1.04). Analyses of the indication for antibiotic use suggest that there is likely some confounding by indication.

LIMITATIONS, REASONS FOR CAUTION

Findings were imprecise for some antibiotic classes and indications for use owing to small numbers of antibiotic users in these categories. There are likely heterogeneous effects of different combinations of indications and treatments, which may be obscured in the overall null results, but cannot be further elucidated in this analysis.

WIDER IMPLICATIONS OF THE FINDINGS

There is little evidence that most antibiotics are associated with reduced fecundability. Antibiotics and the infections they treat are likely associated with fecundability through differing mechanisms, resulting in their association with increased fecundability in some circumstances and decreased fecundability in others.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported through funds provided by the National Institute of Child Health and Human Development, National Institutes of Health (R01-HD086742, R21-HD072326). L.A.W. has received in-kind donations from Swiss Precision Diagnostics, Sandstone Diagnostics, Fertility Friend, and Kindara for primary data collection in PRESTO. The other authors have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

N/A.