Maternal Ureaplasma exposure during pregnancy and the risk of preterm birth and BPD: a meta-analysis

Effects of Ureaplasma urealyticum infection on neonates: a meta-analysis

OBJECTIVE

Ureaplasma urealyticum (UU) is an opportunistic pathogen transmitted from mother to fetus, potentially causing neonatal diseases. Despite extensive research, its association with these diseases remains uncertain. This study analyzes the effects of UU infection on newborns.

METHODS

We performed an exhaustive literature review by searching various databases, including PubMed, EMBASE, and Cochrane, for research articles published before March 2024 on the impact of UU infection on neonates and its association with related diseases. Keywords included "Ureaplasma urealyticum", "Pregnancy Outcomes", "Sepsis", "Cerebral Intraventricular Hemorrhage", "Bronchopulmonary Dysplasia", and "Necrotizing Enterocolitis". Two authors independently screened the literature, extracted data, and evaluated study quality. Meta-analysis was conducted using Stata software, where either a fixed-effects model or a random-effects model was employed to calculate the odds ratio (OR) and 95% confidence interval (CI). The methodological quality of each study was assessed, and the quality of evidence for outcome measures was graded using the GRADE (Grades of Recommendations Assessment, Development and Evaluation, GRADE) system.

RESULTS

Thirteen studies, published between 2011 and 2024, were included, covering regions of China (two studies), South Korea (three studies), Japan (two studies), Austria (three studies), Germany (one study), Belgium (one study), and Italy (one study). Findings indicate that UU infection significantly increased the risk of bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), and sepsis in neonates. However, the correlation between UU infection and necrotizing enterocolitis (NEC) was found not to be significant. Additionally, a descriptive analysis of two studies on UU infection's impact on neonatal pneumonia showed no significant correlation.

CONCLUSION

UU infection significantly increases the risk of BPD, IVH, and sepsis in newborns.

Association between Ureaplasma colonization and bronchopulmonary dysplasia defined by different criteria in very low birth weight infants: A retrospective cohort study

OBJECTIVE

To study the association between Ureaplasma colonization and bronchopulmonary dysplasia (BPD) with different definitions in very low birth weight (VLBW) infants.

METHODS

A retrospective cohort study was performed with VLBW infants admitted from January 2019 to October 2021. Neonates with a positive respiratory tract Ureaplasma culture were included in the study group. Control group infants, matched for gestational age (±1 week), birth weight (±100 g), and birth year, had a negative respiratory tract Ureaplasma culture during the same period. The primary outcomes included the incidence and severity of BPD, defined by various criteria.

RESULTS

The study included 302 neonates (151 in the study group and 151 in the control group). After adjusting for confounders, Ureaplasma colonization was not associated with BPD as defined by the National Institutes of Health (NIH) in 2001 (adjusted odds ratio [aOR]: 0.820, 95% confidence interval [CI]: 0.362-1.860, p = .635). However, it was associated with BPD as defined by the NIH in 2018 (aOR: 2.490, 95% CI: 1.128-5.497, p = .024) and the Neonatal Research Network (NRN) in 2019 (aOR: 2.352, 95% CI: 1.077-5.134, p = .032). Additionally, VLBW infants with Ureaplasma colonization had a higher risk of moderate-severe BPD according to the NIH 2001 (aOR: 2.352, 95% CI: 1.077-5.134, p = .032), NIH 2018 (aOR: 6.339, 95% CI: 1.686-23.836, p = .006), and NRN 2019 definitions (aOR: 3.542, 95% CI: 1.267-9.904, p = .016).

CONCLUSIONS

Ureaplasma colonization is not associated with BPD by the NIH 2001 definition, but is associated with an increased incidence by the NIH 2018 or NRN 2019 definitions.

Causal associations between gut microbiota and premature rupture of membranes: a two-sample Mendelian randomization study

Background

Previous study has indicated a potential link between gut microbiota and maternal pregnancy outcomes. However, the causal relationship between gut microbiota and premature rupture of membranes (PROM) remains a topic of ongoing debate.

Methods

A two-sample Mendelian Randomization (MR) study was used to investigate the relationship between gut microbiota and PROM. Genetic data on gut microbiota was obtained from the MiBioGen consortium's largest genome-wide association study (GWAS) (n=14,306). Genetic data on PROM (3011 cases and 104247 controls) were sourced from publicly available GWAS data from the Finnish National Biobank FinnGen consortium. Various methods including Inverse variance weighted (IVW), MR-Egger, simple mode, weighted median, and weighted mode were utilized to assess the causal relationship by calculating the odd ratio (OR) value and confidence interval (CI). Sensitivity analyses for quality control were performed using MR-Egger intercept tests, Cochran's Q tests, and leave-one-out analyses.

Results

The IVW method revealed that class Mollicutes (IVW, OR=0.773, 95%CI: 0.61-0.981, pval = 0.034), genus Marvinbryantia (IVW, OR=00.736, 95%CI: 0.555-0.977, pval = 0.034), genus Ruminooccaceae UCG003 (IVW, OR=0.734, 95%CI: 0.568-0.947, pval = 0.017) and phylum Tenericutes (IVW, OR=0.773, 95%CI: 0.566-1.067, pval = 0.034) were associated with a reduced risk of PROM, while genus Collinsella (IVW, OR=1.444, 95%CI: 1.028-2.026, pval = 0.034), genus Intestinibacter (IVW, OR=1.304, 95%CI: 1.047-1.623, pval = 0.018) and genus Turicibacter (IVW, OR=1.282, 95%CI: 1.02-1.611, pval = 0.033) increased the risk of PROM. Based on the other four supplementary methods, six gut microbiota may have a potential effect on PROM. Due to the presence of pleiotropy (pval=0.045), genus Lachnoclostridium should be ruled out. No evidence of horizontal pleiotropy or heterogeneity was found in other microbiota (pval >0.05).

Conclusions

In this study, we have discovered a causal relationship between the presence of specific probiotics and pathogens in the host and the risk of PROM. The identification of specific gut microbiota associated with PROM through MR studies offers a novel approach to diagnosing and treating this condition, thereby providing a new strategy for clinically preventing PROM.

Association between Ureaplasma urealyticum colonization and bronchopulmonary dysplasia in preterm infants: a systematic review and meta-analysis

Background

Bronchopulmonary dysplasia (BPD) is the most prevalent chronic lung disease in preterm infants. Studies have shown that Ureaplasma urealyticum (UU) infection is linked to its pathogenesis. However, it remains controversial whether UU colonization in preterm infants increases the risk of developing BPD.

Objective

This study aimed to conduct a systematic review and meta-analysis to summarize the correlation between UU and BPD.

Methods

We searched PubMed, Embase, the Cochrane Library, Web of Science, Wanfang Database, Chinese National Knowledge Infrastructure Database, Chinese Science and Technique Journal Database, and the China Biology Medicine disc from their inception to March 15, 2024. We included cohort and case-control studies investigating the association between UU infections and BPD in preterm infants, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The Newcastle-Ottawa Scale was used for quality assessment. The outcome was defined as the continued need for oxygen or respiratory support at 28 days after birth (BPD28) or at 36 weeks postmenstrual age (BPD36). Considering the potential publication bias in observational studies, we used a random-effects meta-analysis model, assessed heterogeneity (I2), performed subgroup analyses, evaluated publication bias, and graded the quality of evidence.

Results

The meta-analysis included 36 cohort studies encompassing 5,991 participants. Among these, 20 reported on BPD28, 13 on BPD36, and 3 on both. The results indicated a significant association between UU colonization and BPD28 (odds ratio (OR): 2.26, 95% confidence interval (CI): 1.78-2.85, P < 0.00001, 23 studies, very low certainty of evidence) and BPD36 (OR: 2.13, 95% CI: 1.47-3.07, P < 0.0001, 16 studies, very low certainty of evidence).

Conclusion

There is a correlation between UU colonization and the development of BPD in preterm infants. Future research should prioritize well-designed, large-scale, high-quality randomized controlled trials (RCTs) to comprehensively assess the risk of BPD in neonates following UU infection and to provide stronger evidence for clinical screening and prevention strategies to improve the prognosis of affected newborns.

Systematic Review Registration

https://www.crd.york.ac.uk/, identifier (CRD42024524846).

The Role of Ureaplasma Species in Prenatal and Postnatal Morbidity of Preterm Infants: Current Concepts

BACKGROUND

Ureaplasma species are considered commensals of the adult urogenital tract. Yet, in pregnancy, Ureaplasma parvum and Ureaplasma urealyticum have been associated with chorioamnionitis and preterm birth. In preterm infants, Ureaplasma respiratory tract colonization has been correlated with the development of bronchopulmonary dysplasia and has been implicated in the pathogenesis of other complications of prematurity. Controversies on the impact of Ureaplasma exposure on neonatal morbidity, however, remain, and recommendations for screening practices and therapeutic management in preterm infants are missing.

SUMMARY

In this review, we outline clinical and experimental evidence of Ureaplasma-driven fetal and neonatal morbidity, critically examining inconsistencies across some of the existing studies. We explore underlying mechanisms of Ureaplasma-associated neonatal morbidity and discuss gaps in the current understanding including the interplay between Ureaplasma and the maternal urogenital tract and the preterm airway microbiome. Ultimately, we highlight the importance of adequate diagnostics and review the potential efficacy of anti-infective therapies.

KEY MESSAGES

There is strong evidence that perinatal Ureaplasma exposure is causally related to the development of bronchopulmonary dysplasia, and there are conclusive data of the role of Ureaplasma in the pathogenesis of neonatal central nervous system infection. Observational and experimental findings indicate immunomodulatory capacities that might promote an increased risk of secondary infections. The burden of Ureaplasma exposure is inversely related to gestational age - leaving the tiniest babies at highest risk. A better knowledge of contributing pathogen and host factors and modulating conditions remains paramount to define screening and treatment recommendations allowing early intervention in preterm infants at risk.

Prevention of Inflammatory Disorders in the Preterm Neonate: An Update with a Special Focus on Bronchopulmonary Dysplasia

BACKGROUND

The rates of major neonatal morbidities, such as bronchopulmonary dysplasia, necrotizing enterocolitis, preterm white matter disease, and retinopathy of prematurity, remain high among surviving preterm infants. Exposure to inflammatory stimuli and the subsequent host innate immune response contribute to the risk of developing these complications of prematurity. Notably, the burden of inflammation and associated neonatal morbidity is inversely related to gestational age - leaving primarily but not exclusively the tiniest babies at highest risk.

SUMMARY

Avoidance, prevention, and treatment of inflammation to reduce this burden remain a major goal for neonatologists worldwide. In this review, we discuss the link between the host response to inflammatory stimuli and the disease state. We argue that inflammatory exposures play a key role in the pathobiology of preterm birth and that preterm neonates hereafter are highly susceptible to immune stimulation not only from their surrounding environment but also from therapeutic interventions employed in clinical care. Using bronchopulmonary dysplasia as an example, we report clinical studies demonstrating the potential utility of targeting inflammation to prevent this neonatal morbidity. On the contrary, we highlight limitations in our current understanding of how inflammation contributes to disease prevention and treatment.

KEY MESSAGE

To be successful in preventing and treating inflammation-driven morbidity in neonatal intensive care, it may be necessary to better identify at-risk patients and pair therapeutic interventions to key pathways and mediators of inflammation-associated neonatal morbidity identified in pre-clinical and translational studies.

Significance of cervical secretion culture in predicting maternal and fetal outcome in pregnant women with premature rupture of membranes: a retrospective cohort study

Background: To investigate the clinical value of cervical secretion culture in pregnant women with premature rupture of membranes (PROM) in predicting maternal and fetal outcomes. Methods: We retrospectively reviewed clinical records of pregnant women who underwent obstetric examination and delivered in Fujian Maternal and Child Healthcare from December 2013 to December 2016. Pregnant women with a clear diagnosis of PROM, who underwent cervical secretion culture immediately after hospital admission were selected for the study. The primary outcome was the occurrence of chorioamnionitis. The secondary outcome was neonatal admission to the neonatal intensive care unit (NICU). Correlation between maternal and fetal outcomes and the results of the cervical secretion culture was analyzed by one-way analysis and multifactorial analysis, respectively. The predictive efficacy of cervical secretion culture was evaluated using receiver operating characteristic curve (ROC), area under the curve (AUC) and the integrated discrimination improvement (IDI). Results: A total of 7,727 pregnant women with PROM were included in the study. Of them, 1812 had positive cervical secretion cultures (635 positive for mycoplasma infection, 475 for bacterial, 637 for fungal, and 65 for chlamydial infections). Pregnant women with positive mycoplasma and bacterial cultures had higher rates of developing chorioamnionitis compared to women with negative cervical secretion cultures (9%, 12% vs. 1%, respectively). Similarly, positive mycoplasma and bacterial cultures were associated with higher rate of the preterm (before 34 weeks) labor (3%, 3% vs. 1% in women with negative cultures, respectively), and neonatal admission to the NICU (9%, 11% vs. 7%, respectively). After adjusting for various confounding factors, our analysis demonstrated that a positive cervical secretion culture for mycoplasma or bacterial pathogens remained an independent risk factor for chorioamnionitis. Cervical secretion culture outcome was less effective in predicting chorioamnionitis (AUC 0.569) compared to white blood count (WBC) (AUC 0.626) and C-reactive protein (CRP) levels (AUC 0.605). The IDI of the combined predictive model incorporating WBC, CRP, maternal fever and cervical secretion culture results was 0.0029. Conclusion: Positive cervical secretion cultures, especially for mycoplasma and bacteria, are associated with higher incidence of adverse maternal and fetal outcomes. However, the predictive value of this test is poor, and cannot be efficiently used for predicting chorioamnionitis.

Molecular detection of bacteria, placental inflammation, and neonatal sepsis risk

OBJECTIVE

To identify bacteria in umbilical cord tissue and investigate the association with placental inflammation and neonatal sepsis risk score.

STUDY DESIGN

Retrospective cohort study from 2017-2019. RNA was extracted from umbilical cord tissue and NanoString nCounter used to identify seven bacteria genera. Sepsis risk score was calculated using the Kaiser sepsis calculator. Placental histopathology was abstracted from medical records.

RESULTS

Detection of bacterial RNA in the umbilical cord (n = 96/287) was associated with high-stage maternal and fetal acute placental inflammation (maternal 35.4% vs 22.5%, p = 0.03 and fetal 34.4% vs 19.4%, p < 0.01) and maternal vascular malperfusion (36.5% vs 23.0%, p = 0.02). Detection of Ureaplasma spp. was also associated with increased sepsis risk score (1.5/1000 [0.6, 8.6] vs 0.9/1000 [0.2, 2.9], p = 0.04).

CONCLUSION

Umbilical cord bacterial pathogens are linked to fetal and maternal placental inflammation and maternal vascular malperfusion during gestation and associated with increased sepsis risk score in the neonate.

Emerging role of toll-like receptors signaling and its regulators in preterm birth: a narrative review

INTRODUCTION

Despite intensive research, preterm birth (PTB) rates have not decreased significantly in recent years due to a lack of understanding of the underlying causes and insufficient treatment options for PTB. We are committed to finding promising biomarkers for the treatment of PTB.

METHODS

An extensive search of the literature was conducted with MEDLINE/PubMed, and in total, 151 studies were included and summarized in the present review.

RESULTS

Substantial evidence supports that the infection and/or inflammatory cascade associated with infection is an early event in PTB. Toll-like receptor (TLR) is a prominent pattern recognition receptor (PRR) found on both immune and non-immune cells, including fetal membrane cells. The activation of TLR downstream molecules, followed by TLR binding to its ligand, is critical for infection and inflammation, leading to the involvement of the TLR signaling pathway in PTB. TLR ligands are derived from microbial components and molecules released by damaged and dead cells. Particularly, TLR4 is an essential TLR because of its ability to recognize lipopolysaccharide (LPS). In this comprehensive overview, we discuss the role of TLR signaling in PTB, focus on numerous host-derived genetic and epigenetic regulators of the TLR signaling pathway, and cover ongoing research and prospective therapeutic options for treating PTB by inhibiting TLR signaling.

CONCLUSION

This is a critical topic because TLR-related molecules and mechanisms may enable obstetricians to better understand the physiological changes in PTB and develop new treatment and prevention strategies.

Maternal Nutritional Status and the Microbiome across the Pregnancy and the Post-Partum Period

Appropriate nutrition during pregnancy and the post-partum period is vital for both the mothers and their offspring. Both under- and over-nourished status may have important microbial implications on the maternal and infant gut microbiomes. Alterations in the microbiome can have implications for a person's risk of obesity and metabolic diseases. In this review, we examine alterations in the maternal gut, vaginal, placental, and milk microbiomes in the context of pre-pregnancy BMI, gestational weight gain, body composition, gestational diabetes, and maternal diet. We also investigate how the infant gut microbiome may be altered by these different parameters. Many of the microbial changes seen in under- and over-nourished states in birthing parents may result in long-term implications for the health of offspring. Differences in diet appear to be a major driver of the maternal and subsequently milk and offspring microbiomes. Further prospective longitudinal cohort studies are needed to examine nutrition and the microbiome to better understand its implications. Additionally, trials involving dietary interventions in child-bearing age adults should be explored to improve the mother and child's risks for metabolic diseases.

Placing Ureaplasma within the Context of Bronchopulmonary Dysplasia Endotypes and Phenotypes

Different pathophysiological pathways (endotypes), leading to very preterm birth may result in distinct clinical phenotypes of bronchopulmonary dysplasia (BPD). Ureaplasma is a unique player in the pathogenesis of BPD. The interaction between factors inherent to Ureaplasma (virulence, bacterial load, duration of exposure), and to the host (immune response, infection clearance, degree of prematurity, respiratory support, concomitant infections) may contribute to BPD development in a variable manner. The data reviewed herein support the hypothesis that Ureaplasma, as a representative of the infectious/inflammatory endotype, may produce pulmonary damage predominantly in parenchyma, interstitium, and small airways. In contrast, Ureaplasma may have a very limited role in the pathogenesis of the vascular phenotype of BPD. In addition, if Ureaplasma is a key factor in BPD pathogenesis, its eradication by macrolides should prevent BPD. However, various meta-analyses do not show consistent evidence that this is the case. The limitations of current definitions and classifications of BPD, based on respiratory support needs instead of pathophysiology and phenotypes, may explain this and other failures in strategies aimed to prevent BPD. The precise mechanisms through which Ureaplasma infection leads to altered lung development and how these pathways can result in different BPD phenotypes warrant further investigation.

Maternal Origins of Neonatal Infections: What Do Obstetrician-Gynecologist Should/Could Do?

Neonatal infections are responsible for 20% of neonatal deaths yearly. In this review, we focused on the origins of the commoner neonatal infections, and we define the role of obstetricians. Regarding group B Streptococcus, a key measure for the prevention of neonatal infection is the vaginal-rectal culture screening at term pregnancy. Intravenous penicillin is the first-line prophylaxis at the start of labor, with intravenous ampicillin as an alternative. First-generation cephalosporins or clindamycin are recommended in case of penicillin allergy. Concerning urinary tract infections (UTIs), guidelines recommend complete urinalysis and urine culture in the first trimester of pregnancy for the screening of asymptomatic bacteriuria. For lower UTIs, guidelines recommend nitrofurantoin as first-choice antibiotic. Amoxicillin or cefalexin are second-line antibiotics. For upper UTIs, guidelines recommend cephalexin per os as first line. Candida spp. colonization affects 20% of pregnant women; however, congenital fetal candidosis and Candida amnionitis are rare. First-line treatment in case of symptomatic vaginitis during pregnancy or asymptomatic colonization during the third trimester is vaginal clotrimazole. Fluconazole is not approved in pregnancy, especially during the first trimester. Genital mycoplasmas colonization during pregnancy is usually asymptomatic and associated with bacterial vaginosis. Colonization is related to neonatal respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), pneumonia, chorioamnionitis, and sepsis. Macrolides are the first-line treatment along with lactobacillus supplementation. In cases of preterm premature rupture of membranes or preterm labor, ceftriaxone, clarithromycin, and metronidazole are required to prevent intra-amniotic infection. Intra-amniotic infection affects 1 to 5% of deliveries at term and one-third of preterm ones and is associated with perinatal death, early-onset neonatal sepsis, RDS, BPD, pneumonia, meningitis, and prematurity-related diseases. Guidelines recommend a combination of ampicillin and gentamicin, and in case of caesarean section, an additional dose of clindamycin or metronidazole is required. In conclusion, obstetricians should be aware that the treatment of maternal infection during pregnancy can prevent potentially lethal infections in the newborn. KEY POINTS: · Part of neonatal infections starts from maternal infections that must be treated during pregnancy.. · Streptococcus group B and asymptomatic bacteriuria should be investigated in pregnancy and treated.. · Mycoplasma and ureaplasma vaginal colonization during pregnancy is related to negative neonatal outcomes..