Neonatal outcome in preterm deliveries before 34-week gestation - the influence of the mechanism of labor onset

The vaginal immunoproteome for the prediction of spontaneous preterm birth: A retrospective longitudinal study

Background

Preterm birth is the leading cause of neonatal morbidity and mortality worldwide. Most cases of preterm birth occur spontaneously and result from preterm labor with intact (spontaneous preterm labor [sPTL]) or ruptured (preterm prelabor rupture of membranes [PPROM]) membranes. The prediction of spontaneous preterm birth (sPTB) remains underpowered due to its syndromic nature and the dearth of independent analyses of the vaginal host immune response. Thus, we conducted the largest longitudinal investigation targeting vaginal immune mediators, referred to herein as the immunoproteome, in a population at high risk for sPTB.

Methods

Vaginal swabs were collected across gestation from pregnant women who ultimately underwent term birth, sPTL, or PPROM. Cytokines, chemokines, growth factors, and antimicrobial peptides in the samples were quantified via specific and sensitive immunoassays. Predictive models were constructed from immune mediator concentrations.

Results

Throughout uncomplicated gestation, the vaginal immunoproteome harbors a cytokine network with a homeostatic profile. Yet, the vaginal immunoproteome is skewed toward a pro-inflammatory state in pregnant women who ultimately experience sPTL and PPROM. Such an inflammatory profile includes increased monocyte chemoattractants, cytokines indicative of macrophage and T-cell activation, and reduced antimicrobial proteins/peptides. The vaginal immunoproteome has improved predictive value over maternal characteristics alone for identifying women at risk for early (<34 weeks) sPTB.

Conclusions

The vaginal immunoproteome undergoes homeostatic changes throughout gestation and deviations from this shift are associated with sPTB. Furthermore, the vaginal immunoproteome can be leveraged as a potential biomarker for early sPTB, a subset of sPTB associated with extremely adverse neonatal outcomes.

Funding

This research was conducted by the Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services (NICHD/NIH/DHHS) under contract HHSN275201300006C. ALT, KRT, and NGL were supported by the Wayne State University Perinatal Initiative in Maternal, Perinatal and Child Health.

Comparison of Four Tests for Preterm Birth Prediction in Symptomatic Singleton Women: A Prospective Cohort Study

Background and Purpose: It is challenging to predict preterm births accurately. We sought to compare the diagnostic performance of cervical length in predicting preterm birth to those of contraction recording in cardiotocography (CTG), cervical funneling, and Bishop score. Methods: A total of 371 women with singleton pregnancies and threatened preterm labor admitted to tertiary hospitals of northwestern Iran were included in this prospective cohort study and followed up until childbirth. Transvaginal ultrasound was utilized to assess the cervical length and funneling. Also, a CTG test and digital vaginal examination were performed. The data of 218 women were analyzed in the STATA software. The sensitivity and other diagnostic performances, and 95% confidence intervals, were reported. Results: The CTG uterine contraction recording had the highest sensitivity for predicting birth within the next 2 days, whereas a Bishop score ≥6 revealed the highest specificity, positive predictive value, and positive likelihood ratio. Inadequate cervical length for gestational age exhibited a high negative predictive value and the lowest negative likelihood ratio. Conclusion: The cervical length test has good diagnostic and prognostic performance among the four tests for preterm birth. Cervical funneling and CTG tests have poor predictive value, whereas the Bishop score has a superior diagnostic performance to the other tests.

Host-microbiome interactions in distinct subsets of preterm labor and birth

Preterm birth, the leading cause of perinatal morbidity, often follows premature labor, a syndrome whose prevention remains a challenge. To better understand the relationship between premature labor and host-microbiome interactions, we conducted a mechanistic investigation using three preterm birth models. We report that intra-amniotic delivery of LPS triggers inflammatory responses in the amniotic cavity and cervico-vaginal microenvironment, causing vaginal microbiome changes and signs of active labor. Intra-amniotic IL-1α delivery causes a moderate inflammatory response in the amniotic cavity but increasing inflammation in the cervico-vaginal space, leading to vaginal microbiome disruption and signs of active labor. Conversely, progesterone action blockade by RU-486 triggers local immune responses accompanying signs of active labor without altering the vaginal microbiome. Preterm labor facilitates ascension of cervico-vaginal bacteria into the amniotic cavity, regardless of stimulus. This study provides compelling mechanistic insights into the dynamic host-microbiome interactions within the cervico-vaginal microenvironment that accompany premature labor and birth.

Association of delivery risk phenotype with early-onset sepsis in preterm infants

OBJECTIVE

To determine delivery risk phenotype-specific incidence of early-onset sepsis (EOS) among preterm infants.

STUDY DESIGN

Retrospective cohort study of infants born <35 weeks' gestation at four perinatal centers during 2017-2021. Infants were classified into one of six delivery risk phenotypes incorporating delivery mode, presence of labor, and duration of rupture of membranes (ROM). The primary outcome was EOS incidence within the overall cohort and each risk phenotype.

RESULTS

Among 2937 preterm infants, 21 had EOS (0.7%, or 7.1 cases/1000 preterm infants). The majority of EOS cases (13/21, 62%) occurred in the setting of prolonged ROM ≥ 18 h, with a phenotype incidence of 23.8 cases/1000 preterm infants. There were no EOS cases among infants born by cesarean section without ROM (with or without labor), nor via cesarean section with ROM < 18 h without labor.

CONCLUSION

Delivery risk phenotyping may inform EOS risk stratification in preterm infants.

Restrictive prescription of antibiotics in preterm infants with premature rupture of membranes

BACKGROUND

In preterm infants with premature rupture of membranes, antibiotic treatment is frequently started but rates of early onset sepsis are lower. In line with national guidelines, a stratified approach in the decision to start antibiotic treatment using maternal history, clinical impression and biomarkers has been implemented in our level III neonatal center and its results are evaluated.

METHODS

Retrospective cohort study of all preterm newborns with rupture of membranes at least 1 h prior to delivery admitted to our tertiary neonatal intensive care unit. Data on antibiotic exposure, mortality and major neonatal complications were extracted from the electronic patient charts to evaluate the effects and safety of our stratified approach.

RESULTS

Four hundred fifty-six infants met the inclusion criteria. 120 (26%) received primary antibiotics whereas 336 (74%) did not. Of those receiving primary antibiotics, 13 (11%) had a blood culture positive sepsis, 46 (38%) met the criteria of clinical sepsis and in 61 (51%) sepsis was ruled out and antibiotics were stopped after 48-96 h. All infants with blood culture positive sepsis were identified and treated within the first 24 h of life using this approach. None of the 336 infants who were not started on antibiotics primarily needed antibiotic therapy within the first 5 days of life. There were no deaths or major neonatal complications in the group that did not receive empiric antibiotics.

CONCLUSIONS

Our stratified approach for preterm infants with premature rupture of membranes allows a safe reduction of antibiotic exposure even in this high risk population. As a result, only 25% of high risk preterm newborns are treated with antibiotics of which more than half receive less than 5 days of treatment. To treat one infant with blood culture positive sepsis, only 9 infants receive empiric antibiotics.

Validation of a Nomogram for Predicting Preterm Birth in Women With Threatened Preterm Labor: A Prospective Cohort Study in Iranian Tertiary Referral Hospitals

In this prospective cohort study, we aimed to investigate external validity of the Allouche's nomogram to predict preterm birth in symptomatic women in Iran. We employed six variables of cervical length, uterine contractions, rupture of membranes, vaginal bleeding, gestational age, and multiple pregnancy to draw the nomograms. These variables were examined in the first day of women's hospitalization and participants followed up until giving birth. The concordance index of area under the curve (AUC) was used for validation of the nomograms. Of the participants 10% gave birth within 48 hours and 29% before 34 weeks. The nomogram had sufficient accuracy in predicting birth within 48 hours (AUC 0.89 [95% CI 0.82-0.96]) and birth before 34 weeks (AUC 0.89 [95% CI 0.84-0.94]). The optimal risk threshold for nomogram predicting birth within 48 hours was 0.16. Use of these two nomograms, can improve the health of women and their neonates.

[Influence of premature rupture of membranes on the early prognosis of extremely premature infants]

OBJECTIVE

To study the influence of premature rupture of membranes (PROM) on the early prognosis of extremely premature infants, and to provide a basis for the management of extremely premature infants and prenatal consultation.

METHODS

A total of 179 extremely premature singleton infants who were born from 2017 to 2019 were enrolled. According to the presence or absence of PROM, they were divided into two groups: PROM group (n=69) and non-PROM group (n=110). A statistical analysis was performed for maternal data and early prognostic indicators.

RESULTS

Compared with the non-PROM group, the PROM group had significantly higher incidence rates of earlyonset sepsis and necrotizing enterocolitis (NEC) (P < 0.05) and significantly lower rate of use of pulmonary surfactant and incidence rate of hemodynamically significant patent ductus arteriosus (P < 0.05). The multivariate logistic regression analysis showed that chorioamnionitis was an independent risk factor for early-onset sepsis and NEC (OR=11.062 and 9.437 respectively, P < 0.05), and PROM was an independent protective factor against the use of pulmonary surfactant (OR=0.363, P < 0.05).

CONCLUSIONS

PROM increases the incidence rates of early-onset sepsis and NEC in extremely premature infants and does not increase the incidence rates of other adverse outcomes. For pregnant women with PROM at the risk of extremely preterm delivery, prevention of miscarriage and chorioamnionitis is recommended to prolong gestational weeks, reduce the incidence rate of infection, and thus improve the outcome of extremely premature infants.

Neonatal and Childhood Outcomes Following Preterm Premature Rupture of Membranes

Preterm premature rupture of membranes (PPROM) is almost uniformly associated with preterm birth and thus sequelae of prematurity explain many of the complications associated with this condition. However, the unique inflammatory environment and oligohydramnios associated with PPROM may impart unique neonatal and childhood morbidity compared with other preterm birth pathways.

Cellular immune responses in amniotic fluid of women with preterm prelabor rupture of membranes

Background Preterm birth is the leading cause of perinatal morbidity and mortality. Preterm prelabor rupture of membranes (pPROM) occurs in 30% of preterm births; thus, this complication is a major contributor to maternal and neonatal morbidity. However, the cellular immune responses in amniotic fluid of women with pPROM have not been investigated. Methods Amniotic fluid samples were obtained from women with pPROM and a positive (n = 7) or negative (n = 10) microbiological culture. Flow cytometry was performed to evaluate the phenotype and number of amniotic fluid leukocytes. The correlation between amniotic fluid immune cells and an interleukin-6 (IL-6) concentration or a white blood cell (WBC) count in amniotic fluid was calculated. Results Women with pPROM and a positive amniotic fluid culture had (1) a greater number of total leukocytes in amniotic fluid, including neutrophils and monocytes/macrophages and (2) an increased number of total T cells in amniotic fluid, namely CD4+ T cells and CD8+ T cells, but not B cells. The numbers of neutrophils and monocytes/macrophages were positively correlated with IL-6 concentrations and WBC counts in amniotic fluid of women with pPROM. Conclusion Women with pPROM and a positive amniotic fluid culture exhibit a more severe cellular immune response than those with a negative culture, which is associated with well-known markers of intra-amniotic inflammation.

Cumulative Antenatal Risk and Kindergarten Readiness in Preterm-Born Preschoolers

A suboptimal intrauterine environment is thought to increase the probability of deviation from the typical neurodevelopmental trajectory, potentially contributing to the etiology of learning disorders. Yet the cumulative influence of individual antenatal risk factors on emergent learning skills has not been sufficiently examined. We sought to determine whether antenatal complications, in aggregate, are a source of variability in preschoolers’ kindergarten readiness, and whether specific classes of antenatal risk play a prominent role. We recruited 160 preschoolers (85 girls; ages 3–4 years), born ≤33⁶/₇ weeks’ gestation, and reviewed their hospitalization records. Kindergarten readiness skills were assessed with standardized intellectual, oral-language, prewriting, and prenumeracy tasks. Cumulative antenatal risk was operationalized as the sum of complications identified out of nine common risks. These were also grouped into four classes in follow-up analyses: complications associated with intra-amniotic infection, placental insufficiency, endocrine dysfunction, and uteroplacental bleeding. Linear mixed model analyses, adjusting for sociodemographic and medical background characteristics (socioeconomic status, sex, gestational age, and sum of perinatal complications) revealed an inverse relationship between the sum of antenatal complications and performance in three domains: intelligence, language, and prenumeracy (p = 0.003, 0.002, 0.005, respectively). Each of the four classes of antenatal risk accounted for little variance, yet together they explained 10.5%, 9.8%, and 8.4% of the variance in the cognitive, literacy, and numeracy readiness domains, respectively. We conclude that an increase in the co-occurrence of antenatal complications is moderately linked to poorer kindergarten readiness skills even after statistical adjustment for perinatal risk.

Phenotypic overlap in neonatal respiratory morbidity following preterm premature rupture of membranes versus spontaneous preterm labor

BACKGROUND

Bronchopulmonary dysplasia (BPD), a major source of morbidity in premature neonates, has been associated with intrauterine infection and preterm birth. Both preterm premature rupture of membranes (PPROM) and spontaneous preterm labor (sPTL) are linked with intrauterine inflammation. Whether PPROM and sPTL, as two phenotypic categories of preterm birth, are associated with exposure to different degrees and durations of inflammation that might impact fetal lung development is unknown. PPROM may be associated with longer latency until delivery, which is beneficial for neonatal mortality, but may impart greater injury risk to the developing fetal lungs. It is unknown if PPROM is associated with a greater risk of adverse neonatal respiratory outcomes than sPTL.

OBJECTIVE

The objective of this study was to determine if PPROM imparts a differentially greater risk for neonatal BPD than sPTL. A secondary objective was to determine if PPROM was associated with a greater risk of adverse neonatal respiratory outcomes other than BPD and whether gestational latency following PPROM or sPTL diagnosis constitutes a risk factor for fetal lung injury.

STUDY DESIGN

We conducted a retrospective secondary analysis of a large cohort of women at risk for spontaneous preterm birth, who were originally enrolled in a randomized controlled trial of magnesium sulfate versus placebo examining neuroprotection. For our study, we included women with a singleton pregnancy complicated by PPROM or sPTL and delivery between 24 and 34 weeks gestational age. Cases with multiple gestation, congenital anomalies, maternal seropositivity for human immunodeficiency virus, or hypertensive diseases of pregnancy (including preeclampsia) were excluded. The primary outcome was BPD. Secondary outcomes were respiratory distress syndrome (RDS), transient tachypnea of the newborn (TTN), requirement for mechanical ventilation, pneumonia, neonatal sepsis, fetal or neonatal death, and a composite of adverse neonatal respiratory outcomes including (BPD, pneumonia, RDS, and TTN). Statistical analyses included chi-square, Student's t-test and logistic and multiple regression.

RESULTS

A total of 1729 women were included in this analysis including 1554 with PPROM and 175 with sPTL. Women in the PPROM group were more likely to be older, not of Hispanic race, married, more educated, have smoked during pregnancy and have a greater body mass index. The BPD rate was not significantly different following PPROM versus sPTL. Neonates in the PPROM group experienced a lower rate of pneumonia (p = .001), neonatal sepsis (p = .009) and patent ductus arterious (PDA) requiring either medical or surgical therapy (p < .001) than neonates in the sPTL group. Chorioamnionitis was more common in the PPROM group (p = .008) than the sPTL group. After multivariable logistic regression with BPD or composite of adverse neonatal respiratory outcomes as the dependent outcomes, and controlling for gestational age at delivery, maternal smoking history, duration of mechanical ventilation and RDS, there was no significant difference between PPROM and sPTL.

CONCLUSIONS

BPD rates were not significantly different in neonates born to women following PPROM versus sPTL. However, PPROM was associated with lower rates of pneumonia, neonatal sepsis, and PDA requiring therapy in the univariate analysis, but not the multivariate analysis. Neonatal respiratory outcomes may have a similar phenotypic overlap regardless of whether preterm birth follows PPROM or sPTL.