The Association of Inflammatory Biomarker of Neutrophil-to-Lymphocyte Ratio with Spontaneous Preterm Delivery: A Systematic Review and Meta-analysis

Association between neutrophil-to-lymphocyte ratio and epidural-related maternal fever in Chinese parturients: a prospective cohort study

OBJECTIVE

Epidural analgesia could increase the risk of maternal fever during labor, and the potential mechanisms involved inflammation. Neutrophil-to-lymphocyte ratio (NLR) was a sensitive inflammatory composite indicator and related to adverse outcomes in parturients. This study aimed to investigate the association between NLR levels and epidural related maternal fever (ERMF).

METHODS

This prospective cohort study included 614 parturients who underwent epidural analgesia at the Women's Hospital School of Medicine Zhejiang University from November 2021 to May 2023. NLR level was calculated before epidural analgesia for women. The outcome was ERMF. Univariate and multivariate logistic regression models were utilized to explore the association between NLR level and ERMF. And the association was further investigated in subgroups of age, body mass index (BMI) before pregnancy, and parity of delivery. The results were presented as odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Totally, 614 parturients, of whom 171 (27.85%) had ERMF. High NLR level was associated with higher incidence of ERMF (OR = 2.70, 95% CI: 1.58-4.69). Parturients with ERMF had higher proportion of postpartum hemorrhage, longer labor times, and other adverse outcomes in parturients. The association also observed in subgroups of age <35 years old (OR = 2.74, 95% CI: 1.55-4.29), BMI <24 kg/m2 before pregnancy (OR = 2.32, 95% CI: 1.32-4.13), BMI ≥24 kg/m2 before pregnancy (OR = 38.28, 95%CI: 3.67-854.66), primipara (OR = 2.26, 95% CI:1.27-4.04), and multipara (OR = 30.60, 95% CI: 3.73-734.03).

CONCLUSION

High NLR levels were associated with ERMF in women. It indicated that physicians may measure NLR levels as a regular measurement, which may beneficial for pregnancy outcomes.

Predicting Spontaneous Preterm Birth Using the Immunome

Throughout pregnancy, the maternal peripheral circulation contains valuable information reflecting pregnancy progression, detectable as tightly regulated immune dynamics. Local immune processes at the maternal-fetal interface and other reproductive and non-reproductive tissues are likely to be the pacemakers for this peripheral immune "clock." This cellular immune status of pregnancy can be leveraged for the early risk assessment and prediction of spontaneous preterm birth (sPTB). Systems immunology approaches to sPTB subtypes and cross-tissue (local and peripheral) interactions, as well as integration of multiple biological data modalities promise to improve our understanding of preterm birth pathobiology and identify potential clinically actionable biomarkers.

Longitudinal Cervical Length Measurements and Spontaneous Preterm Birth in Singleton and Twin Pregnancies

Importance

Changes in cervical length in twin pregnancies exhibit various patterns, but it is unclear whether the mechanism underlying spontaneous preterm birth (sPTB) is consistent. The existence of detailed phenomena in singleton pregnancies is also unclear.

Objectives

To explore the different patterns in cervical length trajectories in singleton and twin pregnancies and to analyze whether the immunological mechanisms of sPTB are consistent among these cervical length patterns.

Design, Setting, and Participants

This cohort study recruited pregnant individuals who received antenatal care and delivered at Peking University Third Hospital in Beijing, China, between January 1, 2014, and December 31, 2022. Individuals with singleton and twin pregnancies were included.

Exposures

Cervical length measurements and white blood cell (WBC) indicators.

Main Outcomes and Measures

The primary outcome was sPTB. Longitudinal trajectory cluster analysis was used to identify patterns of changes in cervical length in singleton and twin pregnancies. A random-effects model with cubic spline was used to fit and compare the longitudinal trajectory of WBC indicators among early preterm birth, moderate to late preterm birth, and term birth.

Results

A total of 43 559 pregnant individuals were included; of these, 41 706 had singleton pregnancies (mean [SD)] maternal age, 33.0 [4.0] years) and 1853 had twin pregnancies (mean [SD] maternal age, 33.3 [3.6] years). Two distinct patterns of cervical length changes were observed in both singleton and twin pregnancies: shortened (21 366 singletons and 546 twins) and stable (20 340 singletons and 1307 twins). In singleton pregnancies, WBC count was associated with early sPTB in individuals with both shortened cervix (odds ratio [OR], 1.35; 95% CI, 1.00-1.82) and stable cervix (OR, 1.64; 95% CI, 1.07-2.50). However, for twin pregnancies, the association of WBC count (OR, 3.13; 95% CI, 1.58-6.18) with the risk of early sPTB was observed only in individuals with a shortened cervix.

Conclusions and Relevance

This study identified 2 distinct cervical length patterns: shortened and stable. These patterns revealed 2 preterm birth mechanisms in twin pregnancies, with the immunopathogenesis of sPTB found only in the shortened cervix pattern; in singleton pregnancies, maternal immune response was associated with a higher risk of sPTB regardless of a shortened or stable cervix.

Neutrophil-to-Lymphocyte Ratio (NLR) and Platelet-to-Lymphocyte Ratio (PLR) Can Predict Spontaneous Preterm Birth?

Purpose

To investigate the role of neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) in the prediction of spontaneous preterm birth.

Patients and Methods

Data was retrospectively collected from hospital record between February 2018 and November 2022. Pregnant women (n = 78) with a single pregnancy between 24 and 34 weeks of gestation, presented with labor pain, and had regular uterine contractions (threatened preterm labor - TPL) were included. Patients delivered within the first week after TPL were included in group 1 (n = 40) and who delivered after in group 2 (n = 38). Two groups were investigated for NLR and PLR values.

Results

The median cervical length among women who gave birth within a week was significantly lower (24.5 versus 30.0 p < 0.001). The median neutrophil-to-lymphocyte ratio among women who gave birth within a week was significantly higher (6.4 versus 4.5 p < 0.001). The median platelet-to-lymphocyte ratio among women who gave birth within a week was significantly higher (151 versus 131 p < 0.001). The cut-off values to predict preterm birth were >5 for NLR (sensitivity: 90%, specificity: 92.1%), >139 for PLR (sensitivity: 97.5%, specificity: 100%).

Conclusion

NLR and PLR values predict spontaneous preterm birth with high sensitivity and specificity. By predicting preterm birth, the pregnancy process can be managed sensitively and smoothly.

The Predictive Role of Maternal Biological Markers and Inflammatory Scores NLR, PLR, MLR, SII, and SIRI for the Risk of Preterm Delivery

In many countries, preterm birth, defined as birth before 37 completed weeks of gestation, is the primary cause of infant death and morbidity. An increasing body of research suggests that inflammation (both clinical and subclinical) plays a significant role in inducing preterm labor or developing pregnancy problems that lead to premature birth. Consequently, the purpose of this research was to determine the predictive value of the Neutrophil-Lymphocyte Ratio (NLR), derived Neutrophil-Lymphocyte Ratio (dNLR), Monocytes-to-Lymphocyte Ratio (MLR), Platelets-to-Lymphocyte Ratio (PLR), Systemic immune-inflammation index (SII), and systemic inflammatory response index (SIRI), for premature delivery. A retrospective study analyzed a total of 243 eligible pregnancies that resulted in a preterm birth during 2020 and 2021. A control group without a history of preterm birth was matched by age and trimester of laboratory analysis at a 1:1 ratio. Although the number of comorbidities was similar among study groups, the body-mass index estimated for the week of gestation was significantly higher among the patients from the prematurity group, as well as the prevalence of urinary tract infections and smoking. Laboratory data showed that patients with a preterm birth had significantly higher white blood cell count and monocytes, but significantly lower lymphocytes, platelets, and hemoglobin. The NLR, dNLR, PLR, and MLR scores showed to be significantly higher among patients from the prematurity group, but SII and SIRI were not significantly different between the study groups. It was observed that the AUC values of NLR, dNLR, PLR, and MLR were higher than 0.600, respectively NLR had the highest value among the tested scores (AUC = 0.694) and the highest sensitivity in this study (71%). The highest sensibility was achieved by dNLR, with 70%, and an AUC value of 0.655 (p-value = 0.022). PLR had the second-highest AUC value (0.682) and the best score in terms of sensitivity (70%) and sensibility (69%) (p-value = 0.015). Lastly, MLR had the lowest significant AUC score (0.607) and lowest sensitivity/sensibility. The significant cut-off values for the inflammatory scores were 9.0 for NLR, 9.8 for dNLR, 250 for PLR, and 4.07 for MLR. After evaluating the importance of these inflammatory scores, further clinical applications should be conducted to confirm the results and improve therapy and care to reduce the burden of premature deliveries.

Neutrophil depletion in the pre-implantation phase impairs pregnancy index, placenta and fetus development

Maternal neutrophils cells are players in gestational tolerance and fetus delivery. Nonetheless, their actions in each phase of the pregnancy are unknown. We here investigated the role of maternal neutrophil depletion before the blastocyst implantation phase and outcomes in the pregnancy index, placenta, and fetus development. Neutrophils were pharmacologically depleted by i.p. injection of anti-Gr1 (anti-neutrophils; 200 µg) 24 hours after plug visualization in allogeneic-mated C57BL/6/BALB/c mice. Depletion of peripheral neutrophils lasted until 48 hours after anti-Gr1 injection (gestational day 1.5-3.5). On gestational day 5.5, neutrophil depletion impaired the blastocyst implantation, as 50% of pregnant mice presented reduced implantation sites. On gestational day 18.5, neutrophil depletion reduced the pregnancy rate and index, altered the placenta disposition in the uterine horns, and modified the structure of the placenta, detected by reduced junctional zone, associated with decreased numbers of giant trophoblast cells, spongiotrophoblast. Reduced number of placenta cells labeled for vascular endothelial growth factor (VEGF), platelet-endothelial cell adhesion molecule (PECAM-1), and intercellular cell adhesion molecule (ICAM-1), important markers of angiogenesis and adhesiveness, were detected in neutrophil depleted mice. Furthermore, neutrophil depletion promoted a higher frequency of monocytes, natural killers, and T regulatory cells, and lower frequency of cytotoxic T cells in the blood, and abnormal development of offspring. Associated data obtained herein highlight the pivotal role of neutrophils actions in the early stages of pregnancy, and address further investigations on the imbricating signaling evoked by neutrophils in the trophoblastic interaction with uterine epithelium.

The Role of Neutrophils in Pregnancy, Term and Preterm Labour

Neutrophils are surveillance cells, and the first to react and migrate to sites of inflammation and infection following a chemotactic gradient. Neutrophils play a key role in both sterile inflammation and infection, performing a wide variety of effector functions such as degranulation, phagocytosis, ROS production and release of neutrophil extracellular traps (NETs). Healthy term labour requires a sterile pro-inflammatory process, whereas one of the most common causes of spontaneous preterm birth is microbial driven. Peripheral neutrophilia has long been described during pregnancy, and evidence exists demonstrating neutrophils infiltrating the cervix, uterus and foetal membranes during both term and preterm deliveries. Their presence supports a role in tissue remodelling via their effector functions. In this review, we describe the effector functions of neutrophils. We summarise the evidence to support their role in healthy pregnancy and labour and describe their potential contribution to microbial driven preterm birth.

Association of subclinical markers of inflammation with preterm premature rupture of membranes and adverse neonatal results: a case control study

AIM

The study aims to investigate the relationship between subclinical inflammatory factors, which are known to be closely related to inflammation, with preterm premature rupture of membranes (PPROM) and adverse postpartum outcomes.

MATERIALS AND METHODS

The case control type study was conducted between January 1, 2021, and January 2022. 525 pregnant women, including 272 PPROM and 253 normal patients, were added to the study.

RESULTS

There was a positive relationship between PPROM and PCT (platelet crit), MPV (mean platelet volume), NLR (neutrophil-to-lymphocyte ratio), and MLR (monocytes to lymphocyte ratio) values. ROC analysis, PCT > 0.19, MPV > 8.78, NLR > 2.82, and MLR > 0.24 were significantly related to improved risk of PPROM (P < 0.05). In logistic regression analysis, a one-unit rise in PCT resulted in a 3.9-fold rise in RDS risk and a one-unit increase in NLR resulted in a 1.6-fold significant rise in sepsis risk (p < 0.05).

CONCLUSION

NLR and PCT parameters were found to be related to adverse neonatal outcomes.

Role of peripheral inflammatory biomarkers, transforming growth factor-beta and interleukin 6 in predicting peritoneal adhesions following repeat cesarean delivery

BACKGROUND

Repeat cesarean deliveries (CDs) pose a risk in the development of intra-abdominal adhesions.

AIM

We aimed to examine the incidence and severity of adhesions in repeat CDs using a specific scoring system and assess the predictive power of the pre-operative value of transforming growth factor (TGF)-β and interleukin (IL)-6 with selected peripheral inflammatory biomarkers (PIBs) in the prediction of adhesion formation.

METHODS

This prospective study enrolled 91 pregnant women at term, who had previously undergone at least one or more scheduled CDs. PIBs, namely C-reactive protein, white blood cell count, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and systemic immune-inflammation index, TGF-β, and IL-6 were studied according to the presence and location of adhesions.

RESULTS

There was a significant difference only in the variables of the number of CDs, post-operative adhesion index (PAI) score, IL-6, and TGF-β on the presence of adhesion (p < 0.05). The linear regression model revealed that the effect of the number of CDs, PAI score, and IL-6 values on TGF-β was significant (p < 0.05). The effect of the PAI score on TGF-β was higher than that of IL-6. As a reciprocal relationship, the effect of the TGF-β value on the PAI score was also higher than that of IL-6.

CONCLUSION

In patients with a history of repeat CDs, the preoperative determination of TGF-β seems to be an important independent predictor of POA. The adverse events due to post-operative adhesion caused by repeat CDs can be overcome by detecting high-risk patients with a comprehensive assessment and individualized intervention integrated into overall patient management.