Impact of preconception vaginal microbiota on women's risk of spontaneous preterm birth: protocol for a prospective case-cohort study

A prospective cohort study examining the association between the periconceptual vaginal microbiota and first-trimester miscarriage in Kenyan women

BACKGROUND

Studies evaluating the association between the vaginal microbiota and miscarriage have produced variable results.

OBJECTIVE

This study evaluated the association between periconceptual and first-trimester vaginal microbiota and women's risk for miscarriage.

METHODS

At monthly preconception visits and at 9-12 weeks gestation, women collected vaginal swabs for molecular characterisation of the vaginal microbiota. Participants who became pregnant were followed to identify miscarriage versus pregnancy continuing to at least 20 weeks gestation.

RESULTS

Forty-five women experienced miscarriage and 144 had pregnancies continuing to ≥20 weeks. A principal component analysis of periconceptual and first-trimester vaginal bacteria identified by 16S rRNA gene PCR with next-generation sequencing did not identify distinct bacterial communities with miscarriage versus continuing pregnancy. Using taxon-directed quantitative PCR assays, increasing concentrations of Megasphaera hutchinsoni, Mageeibacillus indolicus, Mobiluncus mulieris and Sneathia sanguinegens/vaginalis were not associated with miscarriage. In exploratory analyses, these data were examined as a binary exposure to allow for multivariable modelling. Detection of Mobiluncus mulieris in first-trimester samples was associated with miscarriage (adjusted relative risk [aRR] 2.14, 95% confidence interval [CI] 1.08, 4.22). Additional analyses compared women with early first-trimester miscarriage (range 4.7-7.3 weeks) to women with continuing pregnancies. Mobiluncus mulieris was detected in all eight (100%) first-trimester samples from women with early first-trimester miscarriage compared to 101/192 (52.6%) samples from women with continuing pregnancy (model did not converge). Detection of Mageeibacillus indolicus in first-trimester samples was also associated with early first-trimester miscarriage (aRR 4.10, 95% CI 1.17, 14.31).

CONCLUSIONS

The primary analyses in this study demonstrated no association between periconceptual or first-trimester vaginal microbiota and miscarriage. Exploratory analyses showing strong associations between first-trimester detection of Mobiluncus mulieris and Mageeibacillus indolicus and early first-trimester miscarriage suggest the need for future studies to determine if these findings are reproducible.

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.

Derivation and Internal Validation of a Risk Score for Predicting Chlamydia trachomatis Infection in Kenyan Women Planning Conception

BACKGROUND

Availability of laboratory confirmation of sexually transmitted infections is increasing in low- and middle-income countries, but costs continue to limit their access. Chlamydia trachomatis (CT) is a sexually transmitted infection of significant clinical importance, particularly among women. This study aimed to develop a risk score to identify women with a higher likelihood of CT infection, who could then be prioritized for laboratory testing, in a population of Kenyan women planning pregnancies.

METHODS

Women with fertility intentions were included in this cross-sectional analysis. Logistic regression was used to estimate odds ratios for the association between demographic, medical, reproductive, and behavioral characteristics and the prevalence of CT infection. A risk score was developed and validated internally based on the regression coefficients in the final multivariable model.

RESULTS

The prevalence of CT was 7.4% (51 of 691). A risk score for predicting CT infection, with scores 0 to 6, was derived from participants' age, alcohol use, and presence of bacterial vaginosis. The prediction model yielded an area under the receiver operating curve of 0.78 (95% confidene interval [Cl], 0.72-0.84). A cutoff of ≤2 versus >2 identified 31.8% of women as higher risk with moderate sensitivity (70.6%; 95% Cl, 56.2-71.3) and specificity (71.3%; 95% Cl, 67.7-74.5). The bootstrap-corrected area under the receiver operating curve was 0.77 (95% Cl, 0.72-0.83).

CONCLUSIONS

In similar populations of women planning pregnancies, this type of risk score could be useful for prioritizing women for laboratory testing and would capture most women with CT infections while performing more costly testing in less than half of the population.

Changes in Vaginal Bacteria and Inflammatory Mediators From Periconception Through the Early Postpartum Period in a Cohort of Kenyan Women Without HIV

BACKGROUND

Women's increased risk of HIV acquisition during pregnancy and postpartum may be mediated by changes in vaginal microbiota and/or cytokines.

METHODS

A cohort of 80 Kenyan women who were HIV-1 seronegative contributed 409 vaginal samples at 6 pregnancy time points: periconception, positive pregnancy test result, first trimester, second trimester, third trimester, and postpartum. Concentrations of vaginal bacteria linked with HIV risk and Lactobacillus spp were measured using quantitative polymerase chain reaction. Cytokines were measured by immunoassay.

RESULTS

Based on Tobit regression, later pregnancy time points were associated with lower concentrations of Sneathia spp (P = .01), Eggerthella sp type 1 (P = .002), and Parvimonas sp type 2 (P = .02) and higher concentrations of Lactobacillus iners (P < .001), Lactobacillus crispatus (P < .001), Lactobacillus vaginalis (P < .001), interleukin 6 (P < .001), TNF (P = .004), C-X-C motif chemokine ligand 10 (CXCL10; P < .001), C-C motif ligand 3 (P = .009), C-C motif ligand 4 (P < .001), C-C motif ligand 5 (P = .002), interleukin 1β (P = .02), and interleukin 8 (P = .002). Most cervicovaginal cytokines and vaginal bacteria clustered separately in principal component analysis, except for CXCL10, which did not group with either cytokines or bacteria. The shift toward a Lactobacillus-dominated microbiota during pregnancy mediated the relationship between pregnancy time point and CXCL10.

CONCLUSIONS

Increases in proinflammatory cytokines, but not vaginal bacterial taxa linked with higher HIV risk, could provide an explanation for increased HIV susceptibility during pregnancy and postpartum.

Prevalence and correlates of periodontitis among Kenyan women planning to conceive

Background

Periodontitis has been associated with adverse pregnancy outcomes. Little is known about the burden and risk factors for periodontitis among reproductive age women in sub-Saharan Africa. This analysis aimed to determine the prevalence and correlates of periodontitis among Kenyan women planning to conceive.

Methods

HIV-seronegative, reproductive-age women who were planning to conceive were enrolled and underwent a periodontal examination. Following the US Centers for Disease Control and Prevention clinical case definitions, the presence and severity of periodontitis was determined by establishing the level of clinical periodontal attachment loss and graded in three categories: no/mild, moderate, and severe. Secondary outcomes included the scores on the Gingival Index and Decayed, Missing, and Filled Teeth (DMFT) Index. Correlates of periodontitis were examined using univariable and multivariable logistic regression.

Results

Of the 647 women in the study, 84% (n = 541) had no/mild periodontitis, 15% (n = 97) had moderate periodontitis, and 1% (n = 9) had severe periodontitis. Mild gingivitis was present in 61% (n = 396) of women, while 27% (n = 176) had moderate gingivitis, and 1% (n = 9) had severe gingivitis. The majority (75%, n = 487) of women had a DMFT index in the very low range (score < 5). Periodontitis was observed in 12% (12/101) of nulliparous women compared to 13% (36/286) of women with one prior delivery (prevalence ratio [PR] 1.03, 95% confidence interval [95% CI] 0.57–1.96), 21% (36/170) of women with two prior deliveries (PR 1.78, 95% CI 0.97–3.26), and 24% (22/90) of women with 3 or more prior deliveries (PR 2.06, 95% CI 1.08–3.92).

Conclusion

This study demonstrated a substantial prevalence of moderate-severe periodontitis among women planning to conceive in Kenya. These results highlight the need to address the oral care needs of reproductive age women, particularly those with multiple prior pregnancies.

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.

Nugent Score, Amsel's Criteria, and a Point-of-Care Rapid Test for Diagnosis of Bacterial Vaginosis: Performance in a Cohort of Kenyan Women

ABSTRACT

There are minimal data on the BVBlue test for diagnosis of bacterial vaginosis (BV) in Africa. Among 701 Kenyan women, compared with Nugent score ≥7, the BVBlue test had moderate sensitivity (81.9%; 95% confidence interval, 76.5%-86.5%) and high specificity (92.4%; 95% confidence interval, 89.5%-94.6%). This test may provide a complimentary approach to syndromic management.

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

STUDY QUESTION

Is bacterial vaginosis (BV) associated with fecundability?

SUMMARY ANSWER

Women with BV may be at increased risk for sub-fecundity.

WHAT IS KNOWN ALREADY

While BV has been associated with poor IVF outcomes, the association between vaginal microbiota disruption and non-medically assisted conception has not been thoroughly explored.

STUDY DESIGN, SIZE, DURATION

Kenyan women with fertility intent were enrolled in prospective cohort that included monthly preconception visits with vaginal fluid specimen collection and pregnancy testing. Four hundred fifty-eight women attempting pregnancy for ≤3 menstrual cycles at enrollment were eligible for this fecundability analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

At monthly preconception visits, participants reported the first day of last menstrual period and sexual behavior, underwent pregnancy testing and provided vaginal specimens. Discrete time proportional probabilities models were used to estimate fecundability ratios (FRs) and 95% CI in menstrual cycles with and without BV (Nugent score ≥ 7) at the visit prior to each pregnancy test. We also assessed the association between persistent BV (BV at two consecutive visits) and fecundability.

MAIN RESULTS AND THE ROLE OF CHANCE

Participants contributed 1376 menstrual cycles; 18.5% (n = 255) resulted in pregnancy. After adjusting for age, frequency of condomless sex and study site, BV at the visit prior to pregnancy testing was associated with a 17% lower fecundability (adjusted FR (aFR) 0.83, 95% CI 0.6-1.1). Persistent BV was associated with a 43% reduction in fecundability compared to cycles characterized by optimal vaginal health (aFR 0.57, 95% CI 0.4-0.8).

LIMITATIONS, REASONS FOR CAUTION

Detection of vaginal microbiota disruption using Gram stain and a point-of-care test for elevated sialidase identified a non-optimal vaginal environment, but these non-specific methods may miss important relationships that could be identified by characterizing individual vaginal bacteria and bacterial communities using molecular methods. In addition, results may be subject to residual confounding by condomless sex as this was reported for the prior month rather than for the fertile window during each cycle.

WIDER IMPLICATIONS OF THE FINDINGS

Given the high global prevalence of BV and infertility, an association between BV and reduced fecundability could have important implications for a large number of women who wish to conceive. Multi-omics approaches to studying the vaginal microbiota may provide key insights into this association and identify potential targets for intervention.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by a National Institutes of Health grant (NICHD R01 HD087346-R.S.M.). 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 made possible 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 has received honoraria for consulting from Lupin Pharmaceuticals. L.E.M. receives research funding, paid to the University of Washington, from Hologic Corporation, and has received honoraria for service on scientific advisory boards from Hologic and Nabriva Therapeutics.

TRIAL REGISTRATION NUMBER

N/A.

Trichomoniasis and adverse birth outcomes: a systematic review and meta-analysis

BACKGROUND

Trichomoniasis commonly affects women of childbearing age and has been linked to several adverse birth outcomes.

OBJECTIVE

To elucidate the association between trichomoniasis in pregnant women and adverse birth outcomes, including preterm delivery, prelabour rupture of membranes and low birthweight.

SEARCH STRATEGY

MEDLINE, EMBASE and ClinicalTrials.gov were systematically searched in December 2020 without time or language restrictions.

SELECTION CRITERIA

Original research studies were included if they assessed at least one of the specified adverse birth outcomes in pregnant women with laboratory-diagnosed trichomoniasis.

DATA COLLECTION AND ANALYSIS

Estimates from included articles were either extracted or calculated and then pooled to produce a combined estimate of the association of trichomoniasis with each adverse birth outcome using the random effects model. Heterogeneity was assessed using the I² statistic and Cochran's Q test.

MAIN RESULTS

Literature search produced 1658 publications after removal of duplicates (n = 770), with five additional publications identified by hand search. After screening titles and abstracts for relevance, full text of 84 studies was reviewed and 19 met inclusion criteria for meta-analysis. Significant associations were found between trichomoniasis and preterm delivery (OR 1.27; 95% CI 1.08-1.50), prelabour rupture of membranes (OR 1.87; 95% CI 1.53-2.29) and low birthweight (OR 2.12; 95% CI 1.15-3.91).

CONCLUSIONS

Trichomoniasis in pregnant women is associated with preterm delivery, prelabour rupture of membranes and low birthweight. Rigorous studies are needed to determine the impact of universal trichomoniasis screening and treatment during pregnancy on reducing perinatal morbidity.

TWEETABLE ABSTRACT

This systematic review and meta-analysis found that in the setting of pregnancy, trichomoniasis is significantly associated with multiple adverse birth outcomes, including preterm delivery, low birthweight, and prelabour rupture of membranes.

Gut and Reproductive Tract Microbiota Adaptation during Pregnancy: New Insights for Pregnancy-Related Complications and Therapy

Pregnancy is characterized by maternal adaptations that are necessary to create a welcoming and hospitable environment for the fetus. Studies have highlighted how the microbiota modulates several networks in humans through complex molecular interactions and how dysbiosis (defined as quantitative and qualitative alterations of the microbiota communities) is related to human pathologies including gynecological diseases. This review analyzed how maternal uterine, vaginal, and gut microbiomes could impact on fetus health during the gestational period. We evaluated the role of a dysbiotic microbiota in preterm birth, chorioamnionitis, gestational diabetes mellitus and pre-eclampsia. For many years it has been hypothesized that newborns were sterile organisms but in the past few years this paradigm has been questioned through the demonstration of the presence of microbes in the placenta and meconium. In the future, we should go deeper into the concept of in utero colonization to better understand the role of microbiota through the phases of pregnancy. Numerous studies in the literature have already showed interesting results regarding the role of microbiota in pregnancy. This evidence gives us the hope that microbiota modulation could be a novel strategy to reduce the morbidity and mortality related to pregnancy complications in the future.

Comparative Analysis of Lower Genital Tract Microbiome Between PCOS and Healthy Women

Women with polycystic ovarian syndrome (PCOS) often have a history of infertility and poor pregnancy outcome. The character of the lower genital tract (LGT) microbiome of these patients is still unknown. We collected both vaginal and cervical canal swabs from 47 PCOS patients (diagnosed by the Rotterdam Criteria) and 50 healthy reproductive-aged controls in this study. Variable regions 3–4 (V3–4) were sequenced and analyzed. Operational taxonomic unit (OTU) abundance was noted for all samples. Taxa that discriminated between PCOS and healthy women was calculated by linear discriminant analysis effect size (LEFSe). Results from 97 paired vaginal and cervical canal samples collected from 97 women [mean age 30 (±4 years)] were available for analysis. Using the Rotterdam Criteria, 47 women were diagnosed with PCOS (PCOS, n = 47; control, n = 50). There was no significant difference between cervical canal microbiome and vaginal microbiome from the same individual, however, Lactobacillus spp. was less abundant in both vaginal and cervical canal microbiome of PCOS patients. Several non-Lactobacillus taxa including Gardnerella_vaginalis_00703mash, Prevotella_9_other, and Mycoplasma hominis, were more abundant in the LGT microbiota of PCOS patients. There is a difference between the microorganism in the LGT of patients with PCOS and healthy reproductive-aged women.

The effect of probiotic supplementation during pregnancy on the interaction network of vaginal microbiome

AIM

To evaluate the effect of probiotic supplementation on the vaginal microbiome and provide the effective evidences for clinical management of pregnant women.

METHODS

A total of 28 healthy pregnant women at 32 weeks of gestation were enrolled. The women were divided randomly to the probiotic group where they were prescribed with 2 g combined probiotics daily (13 cases) during the third trimester of pregnancy or to the control group (15 cases) on a voluntary basis. Their vaginal samples were taken for analyzing microbiome with the 16S rDNA amplicon sequencing of V4 region.

RESULTS

There was no significant difference on the clinical characteristics between the probiotic and control groups. The complexity of vaginal microbial network increased from 32 weeks of gestation to antepartum. Lactobacillus was the dominant microbiota. The probiotic supplementation had no obvious influence on the structure of the vaginal microbiome, whereas the relationships of some pivotal vaginal microbiota at the genus level changed in the probiotic group.

CONCLUSION

The vaginal microbiome varied during the third trimester of pregnancy. The features of the vaginal microbiota after probiotic supplementation had shifted and the interaction network had the tendency to be loose. The probiotic supplementation may be useful in regulating the interaction network of vaginal microbiome.