Reducing the rate of preterm birth through a simple antenatal screen-and-treat programme: a retrospective cohort study

Routine screening of abnormal vaginal flora during pregnancy reduces the odds of preterm birth: a systematic review and meta-analysis

Prematurity is the leading cause of perinatal mortality and the morbidity among children under the age of 5. The prevalence of preterm birth is between 5 and 18% worldwide. Approximately 30% of preterm deliveries occur as a consequence of fetal or maternal infections. Bacterial vaginosis can increase the risk of ascending infections. However, there is no recommendation or protocol for screening of abnormal vaginal flora. The aim of this systematic review was to investigate the effectiveness of routine screening of abnormal vaginal flora during pregnancy care. We conducted our systematic search in the following databases: MEDLINE via PubMed, Embase, and Cochrane Library. Studies reporting on pregnant women with no symptoms of bacterial vaginosis were included in our analysis if they provided data on the outcome of their pregnancy. The intervention group went through screening of abnormal vaginal flora in addition to routine pregnancy care. Odds ratio (OR) with 95% confidence intervals (CIs) was used as effect size measure. From each study the total number of patients and number of events was extracted in both the intervention and control arm to calculate OR. Altogether we included 13 trials with 143,534 patients. The screening methods were Gram stain, pH screening, pH self-screening and pH screening combined with Gram stain. Regular screening of vaginal flora compared to no screening significantly reduces the odds of preterm birth before 37 weeks (8.98% vs 9.42%; OR 0.71, CI 0.57-0.87), birthweight under 2500 g (6.53% vs 7.24%; OR 0.64, CI 0.50-0.81), preterm birth before 32 weeks (1.35% vs 2.03%; OR 0.51, CI 0.31-0.85) and birthweight under 1000 g (0.86% vs 2.2%; OR 0.33, CI 0.19-0.57). In conclusion, the routine screening of abnormal vaginal flora might prevent preterm birth, extreme preterm birth, low birthweight deliveries and very low birthweight deliveries. Further research is needed to assess the problem more accurately.

Mixed Vaginitis in the Third Trimester of Pregnancy Is Associated With Adverse Pregnancy Outcomes: A Cross-Sectional Study

Mixed vaginitis is a complex vaginal dysbiosis that differs from single vaginitis. Vaginitis in the third trimester may lead to adverse maternal and neonatal outcomes. The clinical characteristics, microbiological characteristics, and adverse pregnancy outcomes of mixed vaginitis in late pregnancy are worth studying. Therefore, this study investigated the clinical and microbiological characteristics of vaginitis and adverse pregnancy outcomes of patients with mixed vaginitis. We studied 1,674 women in late pregnancy who attended the Tianjin Medical University General Hospital from November, 2019 to October, 2021. We administered standardized questionnaires, performed vaginal examination and sampling plus microscope examinations, and assessed follow-up pregnancy outcomes. We cultured the vaginal discharge of the patients with mixed vaginitis to isolate pathogens and performed antimicrobial susceptibility tests of the isolated pathogens. For the patients with peripartum infection, we collected a sample to isolate pathogens. Among the 1,674 women, 66 (3.9%) had mixed vaginitis. The independent risk factor for mixed vaginitis in late pregnancy was a history of vaginitis during early and middle pregnancy (OR = 5.637, 95% CI: 3.314–9.580). The signs of vaginal erythema (63.6% vs. 42.0%), yellow discharge (81.8% vs. 59.6%), and malodor (31.8% vs. 18.8%) (P <0.05) were significantly higher in patients with mixed vaginitis than in patients with single vaginitis. Bacterial isolates of the vaginal secretions of patients with mixed bacterial vaginitis were mainly the pathogens of aerobic vaginitis and bacterial vaginosis, such as Gardnerella vaginalis, Streptococcus anginosus, and Staphylococcus epidermidis. Pathogen isolation of the vaginal secretions of patients with mixed fungus and bacteria vaginitis mainly included Candida albicans, followed by S. anginosus, Enterococcus faecalis, Staphylococcus hemolyticus, Staphylococcus aureus, Streptococcus agalactiae and Staphylococcus simulans. Women with mixed vaginitis had an increased incidence and risk of peripartum infections (6.1% vs. 1.4%, P <0.05; OR = 3.985, 95% CI:1.214–13.079). Escherichia coli is the main pathogen that causes peripartum infection. Mixed vaginitis in late pregnancy is characterized by a severe and complex phenotype, complex vaginal dysbiosis, and a long course of vaginal dysbiosis. This can lead to an increased incidence and risk of peripartum infection. Therefore, more attention should be paid to patients with mixed vaginitis in the third trimester of pregnancy.

A specific bacterial DNA signature in the vagina of Australian women in midpregnancy predicts high risk of spontaneous preterm birth (the Predict1000 study)

BACKGROUND

Intrauterine infection accounts for a quarter of the cases of spontaneous preterm birth; however, at present, it is not possible to efficiently identify pregnant women at risk to deliver preventative treatments.

OBJECTIVE

This study aimed to establish a vaginal microbial DNA test for Australian women in midpregnancy that will identify those at increased risk of spontaneous preterm birth.

STUDY DESIGN

A total of 1000 women with singleton pregnancies were recruited in Perth, Australia. Midvaginal swabs were collected between 12 and 23 weeks' gestation. DNA was extracted for the detection of 23 risk-related microbial DNA targets by quantitative polymerase chain reaction. Obstetrical history, pregnancy outcome, and demographics were recorded.

RESULTS

After excluding 64 women owing to losses to follow-up and insufficient sample for microbial analyses, the final cohort consisted of 936 women of predominantly white race (74.3%). The overall preterm birth rate was 12.6% (118 births); the spontaneous preterm birth rate at <37 weeks' gestation was 6.2% (2.9% at ≤34 weeks' gestation), whereas the preterm premature rupture of the membranes rate was 4.2%. No single individual microbial target predicted increased spontaneous preterm birth risk. Conversely, women who subsequently delivered at term had higher amounts of Lactobacillus crispatus, Lactobacillus gasseri, or Lactobacillus jensenii DNA in their vaginal swabs (13.8% spontaneous preterm birth vs 31.2% term; P=.005). In the remaining women, a specific microbial DNA signature was identified that was strongly predictive of spontaneous preterm birth risk, consisting of DNA from Gardnerella vaginalis (clade 4), Lactobacillus iners, and Ureaplasma parvum (serovars 3 and 6). Risk prediction was improved if Fusobacterium nucleatum detection was included in the test algorithm. The final algorithm, which we called the Gardnerella Lactobacillus Ureaplasma (GLU) test, was able to detect women at risk of spontaneous preterm birth at <37 and ≤34 weeks' gestation, with sensitivities of 37.9% and 44.4%, respectively, and likelihood ratios (plus or minus) of 2.22 per 0.75 and 2.52 per 0.67, respectively. Preterm premature rupture of the membranes was more than twice as common in GLU-positive women. Adjusting for maternal demographics, ethnicity, and clinical history did not improve prediction. Only a history of spontaneous preterm birth was more effective at predicting spontaneous preterm birth than a GLU-positive result (odds ratio, 3.6).

CONCLUSION

We have identified a vaginal bacterial DNA signature that identifies women with a singleton pregnancy who are at increased risk of spontaneous preterm birth and may benefit from targeted antimicrobial therapy.

Infection-mediated preterm birth: Bacterial origins and avenues for intervention

Preterm birth (PTB) is globally the leading cause of death and disability in children under five years of age. Intra-amniotic infection is well recognised as a major cause of PTB. Importantly, it is the most common cause of extreme PTB (birth prior to 28 weeks gestation), which is frequently associated with a wide range of serious neonatal morbidities. Recent developments in next generation sequencing technologies, combined with many years of culture-based microbiological data have allowed us to gain a deeper understanding of the pathogenesis of infection-mediated PTB. In particular, studies have revealed numerous potential routes to intra-amniotic infection beyond the classically described ascending vaginal route. Currently, antibiotic therapy is standard treatment for suspected or confirmed intra-amniotic infection, although its use in this context has had mixed success due to problems ranging from inappropriate antibiotic selection in relation to the target organism/s, to poor transplacental drug passage. In this review, we will draw together evidence from animal models and human studies to characterise pathways to intra-amniotic infection. We will then thoroughly outline current therapeutic protocols for cases of intra-amniotic infection and suggest potential new avenues for treatment.

Recent advances in the prevention of preterm birth

Preterm birth (PTB) remains a major obstetric healthcare problem and a significant contributor to perinatal morbidity, mortality, and long-term disability. Over the past few decades, the perinatal outcomes of preterm neonates have improved markedly through research and advances in neonatal care, whereas rates of spontaneous PTB have essentially remained static. However, research into causal pathways and new diagnostic and treatment modalities is now bearing fruit and translational initiatives are beginning to impact upon PTB rates. Successful PTB prevention requires a multifaceted approach, combining public health and educational programs, lifestyle modification, access to/optimisation of obstetric healthcare, effective prediction and diagnostic modalities, and the application of effective, targeted interventions. Progress has been made in some of these areas, although there remain areas of controversy and uncertainty. Attention is now being directed to areas where greater gains can be achieved. In this mini-review, we will briefly and selectively review a range of PTB prevention strategies and initiatives where progress has been made and where exciting opportunities await exploitation, evaluation, and implementation.

The colonization with Candida species is more harmful in the second trimester of pregnancy

Purpose

Vaginal colonization with Candida species (spp.) during pregnancy has been associated with impaired pregnancy outcomes. There is a reduction in spontaneous preterm birth among women with recurrent asymptomatic colonization of Candida who were treated with clotrimazole. This study aimed to evaluate the impact of the trimester of vulvovaginal colonization with Candida species.

Methods

Data from all women, who were tested positive for the vaginal colonization with Candida spp. during the first or second trimester of pregnancy, and who registered for a planned birth at our tertiary referral center between 2005 and 2014 were retrospectively analyzed. Their preterm birth rate served as the primary outcome variable. Secondary outcome variables were neonatal birthweight and Apgar score.

Results

Overall, 1066 women were eligible for the study. In 673 women (63%), who were diagnosed with Candida spp. during the first trimester of pregnancy, the rate of preterm birth was 10% (N = 64). In 393 women (37%), who were diagnosed with candidosis during the second trimester, the preterm birth rate was 18% (N = 71; p = 0.0002). Neonates of women, who presented with vulvovaginal candidosis during the first trimester, had a mean birthweight of 3243 g, compared to 2989 g in the group with a second trimester colonization (p < 0.0001).

Conclusion

Women who are colonized with Candida spp. during the second trimester of pregnancy have higher rates of preterm birth and lower neonatal birthweight than those who are colonized during the first trimester of their pregnancy. Screening programs for asymptomatic Candida colonization should take this information into account.

Ureaplasma parvum genotype, combined vaginal colonisation with Candida albicans, and spontaneous preterm birth in an Australian cohort of pregnant women

BACKGROUND

Detection of Ureaplasma, Mycoplasma and Candida spp. in the vagina during pregnancy has previously been associated with preterm birth (PTB). However, the prevalence of these microorganisms and the associated obstetric risks (likely to be population-specific) have not been determined in Australian women; furthermore, in the case of Ureaplasma spp., very few studies have attempted characterisation at the species level and none have examined genotype/serovar status to further refine risk assessment.

METHODS

In order to address these issues we sampled the vaginal fluid of 191 pregnant Australian women at three time points in pregnancy. Culture methods were used for detection of Ureaplasma spp. and Candida spp., and real-time PCR was used for speciation of U. parvum and U. urealyticum, non-albicans Candida spp., Mycoplasma hominis and Mycoplasma genitalium. High-resolution melt PCR was used to genotype U. parvum. Data on various lifestyle factors (including sex during pregnancy and smoking), antimicrobial use and pregnancy outcome were collected on all participants. Chi-square tests were used to assess the association of vaginal microorganisms with PTB.

RESULTS

Detection of Ureaplasma spp. was higher among spontaneous PTB cases, specifically in the presence of U. parvum [77 % preterm (95 % confidence interval (CI) 50-100 %) vs. 36 % term (CI: 29-43 %), p = 0.004], but not U. urealyticum. The association with PTB strengthened when U. parvum genotype SV6 was detected (54 % preterm (CI: 22-85 %) vs. 15 % term (CI: 10-20 %), p = 0.002); this genotype was also present in 80 % (4/5) of cases of PTB <34 weeks gestation. When present with Candida albicans in the same sample, the association with PTB remained strong for both U. parvum [46 % preterm (CI: 15-78 %) vs. 13 % term (CI: 8-18 %), p = 0.005] and U. parvum genotype SV6 [39 % preterm (CI: 8-69 %) vs. 7 % term (CI: 3-11 %), p = 0.003]. With the exception of Candida glabrata, vaginal colonisation status for all organisms was stable throughout pregnancy. Smoking significantly increased the likelihood of detection of all target organisms.

CONCLUSIONS

These data suggest that the presence of different species and serovars of Ureaplasma spp. in the vagina confers an increased risk of spontaneous PTB, findings which may be useful in risk assessment for identifying women who would benefit from antimicrobial treatment.

Detection of Candida spp. in the vagina of a cohort of nulliparous pregnant women by culture and molecular methods: Is there an association between maternal vaginal and infant oral colonisation?

BACKGROUND

Most studies describing vaginal Candida spp. in pregnancy focus on symptomatic vaginitis, rather than asymptomatic colonisation, and solely utilise microbiological culture. The extent to which asymptomatic vaginal carriage may represent a reservoir for infant oral colonisation has been highly debated.

MATERIALS AND METHODS

This study formed part of the Candida and Staphylococcus Transmission Longitudinal Evaluation (CASTLE) study, in Melbourne, Australia, from 2009 to 2011 and used culture and molecular methods to examine vaginal swabs collected late in the third trimester of pregnancy for Candida spp. Oral swabs from infants were also examined using culture methods.

RESULTS

Overall, 80 of 356 (22%) women were positive for Candida spp; the majority being Candida albicans (83%). Candida glabrata and other Candida spp. were also identified, but in much lower numbers. Molecular analysis identified numerous positive samples not detected by culture, including 13 cases of C. albicans. In addition, some positive samples only recorded to genus level by culture were accurately identified as either C. albicans or C. glabrata following molecular analyses. Eighteen infants recorded positive Candida spp. cultures, predominantly C. albicans. However, there were only four (25%) mother/infant dyads where C. albicans was detected.

CONCLUSIONS

This study provides valuable data on asymptomatic colonisation rates of Candida spp. within an asymptomatic population of women late in pregnancy. The utilisation of molecular methods improved the rate of detection and provided a more accurate means for identification of non-albicans Candida spp. The low mother/infant colonisation rate suggests that non-maternal sources are likely involved in determining infant oral colonisation status.

Effect of asymptomatic vaginal colonization with Candida albicans on pregnancy outcome

INTRODUCTION

Vaginal infection is a major causative factor of preterm delivery. The present study was performed to evaluate the effect of asymptomatic vaginal colonization with Candida albicans at early gestation on pregnancy outcome.

MATERIAL AND METHODS

From 2005 to 2014, a total of 8447 women with singleton pregnancies between 10(+0) and 16(+0) gestational weeks were routinely subjected to an antenatal infection screen-and-treat program. Vaginal smears were Gram-stained and microscopically evaluated, and data were retrospectively analyzed. Women exposed to Candida received clotrimazole and were re-tested after 4-6 weeks. Treatment was repeated in case of recurrence. Women with normal or intermediate vaginal flora were considered as non-exposed. Bacterial vaginosis and trichomoniasis were assessed and treated as well. Descriptive data analysis, chi-squared testing and multiple regression analysis with adjustment for potential confounders were performed. Rates of asymptomatic vaginal infections, preterm delivery and low birthweight served as the main outcomes measures.

RESULTS

A normal or intermediate flora was found in 6708 (79.4%) of the screened women; 1142 women (13.5%) showed asymptomatic C. albicans infection. Of this group, 185 women (2.2%) had a recurrence of Candida on vaginal smears. Compared with the non-exposed women with normal or intermediate flora, those with recurrent candidiasis had higher rates of preterm delivery (11.9% vs. 9.5%) and of low birthweight (10.8% vs. 8.0%), as confirmed in the multiple model (p = 0.02).

CONCLUSIONS

Recurrent asymptomatic vaginal colonization with Candida in early pregnancy is associated with preterm delivery and low birthweight. Routine screening and consequent treatment for candidiasis could improve pregnancy outcomes.

The frequent shift to intermediate flora in preterm delivery cases after abnormal vaginal flora screening

The effect of screening and treatment for abnormal vaginal flora on the reduction of preterm deliveries remains controversial. We evaluated whether this screening and treatment reduces the preterm delivery rate for general-population pregnant women. Pregnant women of the Intervention group (n = 574) underwent the screening test and the treatment of vaginal metronidazole during the early second trimester, and those of the Control group (n = 1,161) did not. We compared the preterm delivery rate between these two groups. We also compared the profiles of vaginal flora of the preterm delivery cases with those of the pregnant women with a normal course. There was no significant difference in the preterm delivery rate between these two groups. However, in the preterm delivery cases, a frequent shift to intermediate flora was observed not before but after the screening in the Intervention group. This shift may explain why most of the previous studies failed in regard to the prevention of preterm deliveries.

Genitourinary pathogens and preterm birth

PURPOSE OF REVIEW

The aim is to describe and quantify the association between genitourinary tract infections and preterm birth.

RECENT FINDINGS

Recent studies confirm the importance of identifying and treating both asymptomatic and symptomatic bacteriuria in pregnancy, which is reflected in current antenatal screening guidelines. These guidelines do not recommend routine screening for other asymptomatic lower genital infections (bacterial vaginosis, trichomonas and gonorrhoea) reflecting inconsistent study results, which may reflect differences in study design, size, diagnostics and the timing of screening in pregnancy. Screening for group B Streptococcus (GBS) late in pregnancy is recognized to reduce neonatal disease, but there is a striking lack of robust studies, specifically randomized controlled trials (RCTs), considering the effect of GBS screening earlier in pregnancy on adverse pregnancy outcomes.

SUMMARY

The potential for screening and treatment of genitourinary tract infections in pregnancy to reduce preterm birth rates has been demonstrated in some RCTs. Current guidelines do not reflect these data because of inconsistencies across the body of evidence. There is a need for robust RCTs to confirm or refute earlier data, to inform the optimal timing for screening in pregnancy and to better quantify the contribution of individual infections to the burden of preterm birth.

Should pregnant women with substance use disorders be managed differently?

Pregnant women with substance use disorders have multiple special needs, which might be best managed within a multiprofessional treatment setting involving medical, psychological and social care. Adequate treatment provision remains a challenge for healthcare professionals, who should undergo special training and education when working with this patient population. Careful assessment and screening is necessary to tailor interventions individually to the woman's needs in order to achieve beneficial clinical outcomes for mothers and newborns, whereas the choice of treatment options highly depends on the type of substance of abuse and evidence-based treatment interventions available. Economic considerations have shown that early multiprofessional treatment might yield better clinical outcomes and save healthcare costs over the lifespan.