Infection and the role of inflammation in preterm premature rupture of the membranes

Vaginal matrix metalloproteinase-9 (MMP-9) as a potential early predictor of preterm birth

OBJECTIVES

To evaluate the differences in vaginal matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMPs) in pregnant patients with a history of prior preterm birth compared with controls.

METHODS

A prospective cohort pilot study recruited patients during prenatal care with history of prior spontaneous preterm birth (high-risk group) or no history of preterm birth (low-risk/controls). Inclusion criteria were singleton gestation at 11-16 weeks and between 18 and 55 years of age. Exclusion criteria were diabetes mellitus, hypertension, diseases affecting the immune response or acute vaginitis. A vaginal wash was performed at time of enrollment, and patients were followed through delivery. Samples were analyzed using semi-quantitative analysis of MMPS and TIMPS. The study was approved by the IRB and a p value <0.05 was considered significant.

RESULTS

A total of 48 pregnant patients were recruited: 16 with a history of preterm birth (high-risk group) and 32 with no history of preterm birth (low-risk group/controls). Groups were similar in age, race, BMI, and delivery mode. The high-risk group had more multiparous women (100 vs. 68.8 %; p=0.02), a greater preterm birth rate (31.2 vs. 6.3 %; p=0.02), and a lower birth weight (2,885 ± 898 g vs. 3,480 ± 473 g; p=0.02). Levels of vaginal MMP-9 were greater in high-risk patients than low-risk patients (74.9 % ± 27.0 vs. 49.4 % ± 31.1; p=0.01). When dividing the cohort into patients that had a spontaneous preterm birth (7/48, 14.6 %) vs. those with a term delivery (41/48, 85.4 %), the vaginal MMP-9 remained elevated in the cohort that experienced a preterm birth (85.46 %+19.79 vs. 53.20 %+31.47; p=0.01). There were no differences in the other MMPS and in TIMPs between high and low-risk groups.

CONCLUSIONS

There was an increase in vaginal MMP-9 during early pregnancy in those at high risk for preterm birth and in those who delivered preterm, regardless of prior pregnancy outcome. Vaginal MMP-9 may have potential as a marker of increased risk of preterm birth.

CX3CL1/Fractalkine as a biomarker for early pregnancy prediction of preterm premature rupture of membranes

OBJECTIVES

The objective of our study was to evaluate serum CX3CL1/Fractalkine, a monocyte/macrophage chemoattractant expressed in cytotrophoblasts and decidual cells, as a predictive biomarker for the occurrence of preterm premature rupture of membranes (PPROM).

METHODS

A case-control study of 438 pregnancies including 82 PPROM cases and 64 preterm labor with intact membranes cases with blood samples collected at first trimester, second trimester and delivery was conducted. The predictive ability of CX3CL1 and maternal risk factors for the occurrence of PPROM was assessed by receiver operating characteristic curve analysis. A second, independent cohort was prospectively constituted to confirm the case-control study results.

RESULTS

First trimester CX3CL1 was significantly increased in PPROM cases when compared to matched controls. Multivariate regression analysis highlighted a significant difference for CX3CL1 measured during the first trimester (p<0.001). Alone, CX3CL1 predicts PPROM with a 90 % sensitivity and a specificity around 40 %. The area under the receiver operating characteristic curve for PPROM prediction were 0.64 (95% confidence interval: 0.57-0.71) for first trimester CX3CL1, and 0.61 (95% confidence interval: 0.54-0.68) for maternal risk factors (body mass index<18.5 kg/m2, nulliparity, tobacco use and the absence of high school diploma). The combination of CX3CL1 and maternal risk factors significantly improved the area under the curve: 0.72 (95% confidence interval: 0.66-0.79) (p<0.001). The results were confirmed on a second independent cohort.

CONCLUSIONS

CX3CL1 is a promising blood biomarker in the early (first trimester) prediction of PPROM.

Changes in serum inflammatory factors in group B streptococcal infection and their predictive value for premature rupture of membranes complicated by chorioamnionitis

Objective: The aim of this study as to unveil changes in serum inflammatory factors in pregnant women with genital tract group B Streptococcus (GBS) infection and their predictive value for premature rupture of membranes (PROM) complicated by chorioamnionitis (CS) and adverse pregnancy outcomes. Methods: The value of serum inflammatory factor levels in predicting PROM complicating CS and adverse pregnancy outcomes in GBS-infected pregnant women was evaluated by ELISA. Results: Serum IL-6, TNF-α, PCT and hs-CRP levels were higher in pregnant women with GBS infection. The combined diagnosis of these factors had excellent diagnostic value in PROM complicating CS and adverse pregnancy outcomes. Conclusion: Joint prediction of IL-6, TNF-α, PCT and hs-CRP has the best predictive value for PROM complicating CS and adverse pregnancy outcomes.

Clinical chorioamnionitis at term: definition, pathogenesis, microbiology, diagnosis, and treatment

Clinical chorioamnionitis, the most common infection-related diagnosis in labor and delivery units, is an antecedent of puerperal infection and neonatal sepsis. The condition is suspected when intrapartum fever is associated with two other maternal and fetal signs of local or systemic inflammation (eg, maternal tachycardia, uterine tenderness, maternal leukocytosis, malodorous vaginal discharge or amniotic fluid, and fetal tachycardia). Clinical chorioamnionitis is a syndrome caused by intraamniotic infection, sterile intraamniotic inflammation (inflammation without bacteria), or systemic maternal inflammation induced by epidural analgesia. In cases of uncertainty, a definitive diagnosis can be made by analyzing amniotic fluid with methods to detect bacteria (Gram stain, culture, or microbial nucleic acid) and inflammation (white blood cell count, glucose concentration, interleukin-6, interleukin-8, matrix metalloproteinase-8). The most common microorganisms are Ureaplasma species, and polymicrobial infections occur in 70% of cases. The fetal attack rate is low, and the rate of positive neonatal blood cultures ranges between 0.2% and 4%. Intrapartum antibiotic administration is the standard treatment to reduce neonatal sepsis. Treatment with ampicillin and gentamicin have been recommended by professional societies, although other antibiotic regimens, eg, cephalosporins, have been used. Given the importance of Ureaplasma species as a cause of intraamniotic infection, consideration needs to be given to the administration of antimicrobial agents effective against these microorganisms such as azithromycin or clarithromycin. We have used the combination of ceftriaxone, clarithromycin, and metronidazole, which has been shown to eradicate intraamniotic infection with microbiologic studies. Routine testing of neonates born to affected mothers for genital mycoplasmas could improve the detection of neonatal sepsis. Clinical chorioamnionitis is associated with decreased uterine activity, failure to progress in labor, and postpartum hemorrhage; however, clinical chorioamnionitis by itself is not an indication for cesarean delivery. Oxytocin is often administered for labor augmentation, and it is prudent to have uterotonic agents at hand to manage postpartum hemorrhage. Infants born to mothers with clinical chorioamnionitis near term are at risk for early-onset neonatal sepsis and for long-term disability such as cerebral palsy. A frontier is the noninvasive assessment of amniotic fluid to diagnose intraamniotic inflammation with a transcervical amniotic fluid collector and a rapid bedside test for IL-8 for patients with ruptured membranes. This approach promises to improve diagnostic accuracy and to provide a basis for antimicrobial administration.

Association of 25-Hydroxyvitamin D with Preterm Birth and Premature Rupture of Membranes: A Mendelian Randomization Study

Low vitamin D (VitD) level is a risk factor for preterm birth (PTB), but the results of previous studies remained inconsistent, which may be influenced by the confounding factors and different types of PTB. We performed Mendelian randomization (MR) to uncover the association of 25-hydroxyvitamin D (25(OH)D) with PTB, premature rupture of membranes (PROM), and preterm premature rupture of membranes (PPROM). This study was conducted in Zhoushan Maternal and Child Health Hospital, Zhejiang, from August 2011 to March 2022. Plasma 25(OH)D levels in three trimesters of pregnancy were measured. We conducted an MR analysis utilizing a genetic risk score (GRS) approach, which was based on VitD-associated single-nucleotide polymorphisms. The prospective cohort study included 3923 pregnant women. The prevalence of PTB, PROM, and PPROM were 6.09%, 13.18%, and 1.33%, respectively. Compared to those without vitamin D deficiency (VDD), only vaginally delivering pregnant women with VDD had a 2.69 (1.08-6.68) times risk of PTB. However, MR analysis did not support the association. One-unit higher GRS was not associated with an increased risk of PTB, regardless of the trimesters (OR [95% CI]: 1.01 [0.93-1.10], 1.06 [0.96-1.18], and 0.95 [0.82-1.10], respectively). When further taking PROM and PPROM as the outcomes, the MR analysis also showed no consistent evidence of a causal effect of VitD levels on the risk of them. Our MR analyses did not support a causal effect of 25(OH)D concentrations in the three trimesters on PTB, PROM, and PPROM.

Efficacy of prophylactic antibiotics for preterm premature rupture of membranes: a systematic review and network meta-analysis

OBJECTIVE

Various prophylactic antibiotic regimens are used in the management of preterm premature rupture of membranes. We investigated the efficacy and safety of these regimens in terms of maternal and neonatal outcomes.

DATA SOURCES

We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials from inception to July 20, 2021.

STUDY ELIGIBILITY CRITERIA

We included randomized controlled trials involving pregnant women with preterm premature rupture of membranes before 37 weeks of gestation and a comparison of ≥2 of the following 10 antibiotic regimens: control/placebo, erythromycin, clindamycin, clindamycin plus gentamicin, penicillins, cephalosporins, co-amoxiclav, co-amoxiclav plus erythromycin, aminopenicillins plus macrolides, and cephalosporins plus macrolides.

METHODS

Two investigators independently extracted published data and assessed the risk of bias with a standard procedure following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Network meta-analysis was conducted using the random-effects model.

RESULTS

A total of 23 studies that recruited a total of 7671 pregnant women were included. Only penicillins (odds ratio, 0.46; 95% confidence interval, 0.27-0.77) had significantly superior effectiveness for maternal chorioamnionitis. Clindamycin plus gentamicin reduced the risk of clinical chorioamnionitis, with borderline significance (odds ratio, 0.16; 95% confidence interval, 0.03-1.00). By contrast, clindamycin alone increased the risk of maternal infection. For cesarean delivery, no significant differences were noted among these regimens.

CONCLUSION

Penicillins remain the recommended antibiotic regimen for reducing maternal clinical chorioamnionitis. The alternative regimen includes clindamycin plus gentamicin. Clindamycin should not be used alone.

The change of inflammatory status and vaginal flora in pregnant women with premature rupture of membranes

Introduction. Premature rupture of the membrane (PROM) can trigger significant maternal complications, even maternal and fetal morbidity or mortality.Hypothesis. Inflammatory status and vaginal flora might be utilized to predict the occurrence of PROM.Aim. To explore the association between the occurrence of PROM and vaginal flora and inflammatory status alteration.Methodology. A case-control cross-sectional study was carried out on 140 pregnant women with or without PROM. Socio-demographic characteristics, vaginal flora assessment, pregnant outcomes and Apgar score information were retrieved.Results. Pregnant women with PROM showed an increased incidence of vulvovaginal candidiasis (VVC), trichomonas vaginitis (TV) and bacterial vaginitis (BV) with dysregulated vaginal flora and diminished fetal tolerance of labour indicated by down-regulated Apgar score. The increased rate of prematurity, puerperal infection and neonatal infection could be detected in PROM patients with imbalanced vaginal flora compared with PROM patients with normal vaginal flora. ROC analysis suggested IL-6 and TNF-α yielded the best discrimination for the prediction of PROM.Conclusion. Altered vaginal and inflammatory status are associated with PROM, and IL-6 and TNF-α can predict the occurrence of PROM.

NETs promote ROS production to induce human amniotic epithelial cell apoptosis via ERK1/2 signaling in spontaneous preterm birth

PROBLEM

Premature birth is a common obstetric complication but its pathogenesis is unclear. Inflammation at the maternal-fetal interface in preterm labor leads to the infiltration of neutrophils, which promotes inflammatory responses and induces the degradation of extracellular matrix and cell apoptosis, thus contributing to preterm labor. It is unclear whether neutrophil extracellular traps (NETs), a functional form of neutrophils, are involved in preterm labor.

METHODS OF STUDY

After collecting amniotic membranes from research objects, we localized NETs by immunofluorescence and evaluated the expression of matrix metalloproteinase (MMP)-9 and MMP-2 by western blotting. Primary human amniotic epithelial cells (hAECs) subjected to treatment with NETs, 5-ethynyl-20-deoxyuridine cell proliferation assay, lactate dehydrogenase (LDH) assay, western blotting, and flow cytometry apoptosis assay were used to determine the effects of NETs on hAECs. We also elucidated possible mechanisms underlying the effects.

RESULTS

Compared with normal term women, NETs infiltration and MMP-9 expression in the amniotic membrane from preterm women had increased. Thereafter, NETs might suppress the proliferation and promote the apoptosis of hAECs. Furthermore, after NETs treatment, the mitochondrial membrane potential was significantly decreased, ERK1/2 phosphorylation expression was upregulated and reactive oxygen species (ROS) production was increased in hAECs. Changes in cell proliferation, LDH release, and cell apoptosis level due to NETs could be reversed by ROS inhibitor or ERK phosphorylation inhibitors.

CONCLUSIONS

NETs can promote the apoptosis of hAECs via ERK1/2 pathways dependent on ROS release.

The serotonin reuptake inhibitor fluoxetine induces human fetal membrane sterile inflammation through p38 MAPK activation

Serotonin Reuptake Inhibitors (SRIs) are often used as first line therapy for depression and other psychiatric disorders. SRI use during pregnancy is associated with preterm premature rupture of membranes (PPROM) and subsequent preterm birth. The objective of this study was to investigate the mechanism(s) responsible for SRI-associated PPROM. Putative mechanisms underlying PPROM include fetal membrane (FM) inflammation, increased apoptosis, and/or accelerated senescence, the later which may be reversed by statins. Human FM explants from normal term deliveries without labor, infection, or antidepressant use were treated with or without the SRI, fluoxetine (FLX), either alone or in the presence of a p38 MAPK inhibitor or the statins, simvastatin or rosuvastatin. FMs were also collected from women either unexposed or exposed to FLX during pregnancy. FLX significantly increased FM p38 MAPK activity and secretion of inflammatory IL-6. Inhibition of p38 MAPK reduced FM IL-6 secretion in response to FLX. Statins did not reduce the SRI-induced FM IL-6 production. FMs from women exposed to FLX during pregnancy expressed elevated levels of p38 MAPK activity compared to matched unexposed women. FMs exposed to FLX did not exhibit signs of increased apoptosis and/or accelerated senescence. These results indicate that the SRI, FLX, may induce sterile FM inflammation during pregnancy through activation of the p38 MAPK pathway, and in the absence of apoptosis and senescence. These findings may better inform clinicians and patients as they weigh the risks and benefits of SRI antidepressant treatment during pregnancy.

Preterm Birth and Corticotrophin-Releasing Hormone as a Placental Clock

Preterm birth worldwide remains a significant cause of neonatal morbidity and mortality, yet the exact mechanisms of preterm parturition remain unclear. Preterm birth is not a single condition, but rather a syndrome with a multifactorial etiology. This multifactorial nature explains why individual predictive measures for preterm birth have had limited sensitivity and specificity. One proposed pathway for preterm birth is via placentally synthesized corticotrophin-releasing hormone (CRH). CRH is a peptide hormone that increases exponentially in pregnancy and has been implicated in preterm birth because of its endocrine, autocrine, and paracrine roles. CRH has actions that increase placental production of estriol and of the transcription factor nuclear factor-κB, that likely play a key role in activating the myometrium. CRH has been proposed as part of a placental clock, with early activation of placental production resulting in preterm birth. This article will review the current understanding of preterm birth, CRH as an initiator of human parturition, and the evidence regarding the use of CRH in the prediction of preterm birth.

Preterm labor with intact membranes: a simple noninvasive method to identify patients at risk for intra-amniotic infection and/or inflammation

OBJECTIVE

To develop a noninvasive scoring system to identify patients at high risk for intra-amniotic infection and/or inflammation, which would reduce the need for amniocentesis.

METHODS

This prospective cohort study comprised patients admitted with preterm labor and intact membranes (20-34 weeks of gestation) who underwent a transabdominal amniocentesis and for whom concentrations of quantitative cervical fetal fibronectin and of maternal serum C-reactive protein (CRP) were determined. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms. Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. Multivariate logistic regression analysis was performed to identify intra-amniotic infection/inflammtion with noninvasive parameters that had a significant relationship with univariate analysis. With four parameters identified by multivariate analysis, we generated a noninvasive risk scoring system.

RESULTS

Of the study population consisting of 138 singleton pregnant women, (1) the overall rate of intra-amniotic infection/inflammation was 28.3% (39/138); (2) four parameters were used to develop a noninvasive risk scoring system [i.e. cervical fetal fibronectin concentration (score 0-2), maternal serum CRP concentration (score 0-2), cervical dilatation (score 0-2), and gestational age at presentation (score 0-1)]; the total score ranges from 0 to 7; 3) the area under the curve of the risk score was 0.96 (95% confidence interval (CI), 0.92-0.99), significantly higher than that of each predictor in the identification of intra-amniotic infection/inflammation (p < .001, for all); 4) the risk score with a cutoff of 4 had a sensitivity of 94.9% (37/39), a specificity of 90.9% (90/99), a positive predictive value of 80.4% (37/46), a negative predictive value of 97.8% (90/92), a positive likelihood ratio of 10.4 (95% CI, 5.6-19.5), and a negative likelihood ratio of 0.06 (95% CI, 0.15-0.22) in the identification of intra-amniotic infection/inflammation.

CONCLUSIONS

(1) The combination of four parameters (concentrations of cervical fetal fibronectin and maternal serum CRP, cervical dilatation, and gestational age) was independently associated with intra-amniotic infection and/or inflammation; and (2) the risk scoring system comprised of the combination of 4 noninvasive parameters was sensitive and specific to identify the patients at risk for intra-amniotic infection and/or inflammation.

Analysis of risk factors related to extremely and very preterm birth: a retrospective study

Background:

Preterm birth is one of the main causes of perinatal morbidity and mortality and imposes a heavy burden on families and society. The aim of this study was to identify risk factors and analyze birth conditions and complications of newborns born at < 32 gestational weeks for extremely preterm (EP) and very preterm (VP) birth in the clinic to further extend the gestational period.

Methods:

We performed a retrospective cohort study and collected data from 1598 pregnant women and 1660 premature newborns (excluding 229 premature babies who died due to severe illness and abandonment) admitted to the Obstetrics and Gynecology Hospital Affiliated with Nanjing Medical University in China from 2016 to 2020. We compared women’s and newborns’ characteristics by t-tests and Chi-square tests for continuous and categorical variables, respectively. Multivariable logistic regression was performed to estimate the effects of risk factors on EP and VP birth.

Results:

We identified 3 independent risk factors for EP birth: cervical incompetency (P < 0.001); multiple pregnancy (P < 0.01), primipara (P < 0.001). Additionally, we identified 4 independent risk factors for VP birth: gestational diabetes mellitus (GDM) (P < 0.05), preterm premature rupture of membrane (PPROM) (P < 0.01), fetal intrauterine distress (P < 0.001), and hypertensive disorder complicating pregnancy (HDCP) (P < 0.001). In addition, pairwise comparisons revealed statistically significant differences in the incidence rates of neonatal pneumonia, bronchopulmonary dysplasia (BPD) and sepsis between the 28–28 + 6 and 29–29 + 6 weeks of gestation groups (P < 0.05). Compared with 28–28 + 6 weeks of gestation, neonatal complications were significantly more common at < 26 weeks of gestation (P < 0.05). The incidence rates of neonatal intracranial hemorrhage(NICH), patent ductus arteriosus(PDA), patent foramen ovale(PFO), pneumonia, BPD and sepsis were significantly higher in the 26–26 + 6 and 27–27 + 6 gestational weeks than in the 28–28 + 6 gestational weeks (P < 0.05).

Conclusion:

PPROM, is the most common risk factor for EP and VP birth, and cervical insufficiency, multiple pregnancy, and primipara are independent risk factors for EP birth. Therefore, during pregnancy, attention should be devoted to the risk factors for PPROM, and reproductive tract infection should be actively prevented to reduce the occurrence of PPROM. Identifying the risk factors for cervical insufficiency, actively intervening before pregnancy, and cervical cervix ligation may be considered to reduce the occurrence of EP labor. For iatrogenic preterm birth, the advantages and disadvantages should be carefully weighed, and the gestational period should be extended beyond 28 weeks to enhance the safety of the mother and child and to improve the outcomes of preterm birth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-05119-7.

Haematological changes from conception to childbirth: An indicator of major pregnancy complications

BACKGROUND

About 800 women die every day worldwide from pregnancy-related complications, including excessive blood loss, infections and high-blood pressure (World Health Organization, 2019). To improve screening for high-risk pregnancies, we set out to identify patterns of maternal hematological changes associated with future pregnancy complications.

METHODS

Using mixed effects models, we established changes in 14 complete blood count (CBC) parameters for 1710 healthy pregnancies and compared them to measurements from 98 pregnancy-induced hypertension, 106 gestational diabetes and 339 postpartum hemorrhage cases.

RESULTS

Results show interindividual variations, but good individual repeatability in CBC values during physiological pregnancies, allowing the identification of specific alterations in women with obstetric complications. For example, in women with uncomplicated pregnancies, haemoglobin count decreases of 0.12 g/L (95% CI -0.16, -0.09) significantly per gestation week (p value <.001). Interestingly, this decrease is three times more pronounced in women who will develop pregnancy-induced hypertension, with an additional decrease of 0.39 g/L (95% CI -0.51, -0.26). We also confirm that obstetric complications and white CBC predict the likelihood of giving birth earlier during pregnancy.

CONCLUSION

We provide a comprehensive description of the associations between haematological changes through pregnancy and three major obstetric complications to support strategies for prevention, early-diagnosis and maternal care.

Risk factors and maternal/fetal outcomes of pregnant women with abruptio placenta: a retrospective, descriptive study

Aim: Abruptio placenta is one of the most important causes of antepartum bleeding and is linked to the major (unpleasant) obstetrics consequences leading to the increased risks of fetal and maternal morbidity and mortality. The aim of our study is to establish a prevalence in our tertiary hospital and find out the fetal and maternal outcomes, along with the patient’s demographic characteristics and risk factors of abruptio placenta. Material and Method: This trial was carried out in Profesör Doktor Cemil Taşçıoğlu State Hospital, between January 2018 and March 2022. Patient data were extracted from computer system, and files were retrospectively evaluated. We established the fetal and maternal outcomes, along with the demographic characteristics and risk factors of abruptio placenta. All analysis was performed using SPSS software (Statistical Package for the Social Sciences, version 25.0, SPSS Inc., Chicago, IL, USA). Results: Within the review period there were 7126 deliveries. And 112 cases with abruptio placenta were seen out of the total deliveries. In our population, prevalence of the abruptio placenta was calculated as 1.5%. Because of the incomplete data in certain files, only a total of 102 cases (91%) were eligible for the study. Conclusion: In conclusion, since the abruptio placenta is highly associated with maternal and fetal morbidity and mortality, timely diagnosis is crucial to prevent devastating consequenuces.

Possible effects of dietary advanced glycation end products on maternal and fetal health: a review

Excessive accumulation of advanced glycation end products (AGEs) in the body has been associated with many adverse health conditions. The common point of the pathologies associated at this point is oxidative stress and inflammation. Pregnancy is an important period in which many physiological, psychological, and biological changes are experienced. Along with the physiological changes that occur during this period, the mother maintaining an AGE-rich diet may cause an increase in the body's AGE pool and may increase oxidative stress and inflammation, as seen in healthy individuals. Studies have reported the negative effects of maternal AGE levels on maternal and fetal health during pregnancy. Although gestational diabetes, preeclampsia, endothelial dysfunction, and pelvic diseases constitute maternal complications, a number of pathological conditions such as intrauterine growth retardation, premature birth, neural tube defect, neurobehavioral developmental disorders, fetal death, and neonatal asphyxia constitute fetal complications. It is thought that the mechanisms of these complications have not been confirmed yet and more clinical studies are needed on this subject. The possible effects of dietary AGE levels during pregnancy on maternal and fetal health are examined in this review.

Epithelial to mesenchymal transition (EMT) of feto-maternal reproductive tissues generates inflammation: a detrimental factor for preterm birth

Human pregnancy is a delicate and complex process where multiorgan interactions between two independent systems, the mother, and her fetus, maintain pregnancy. Intercellular interactions that can define homeostasis at the various cellular level between the two systems allow uninterrupted fetal growth and development until delivery. Interactions are needed for tissue remodeling during pregnancy at both fetal and maternal tissue layers. One of the mechanisms that help tissue remodeling is via cellular transitions where epithelial cells undergo a cyclic transition from epithelial to mesenchymal (EMT) and back from mesenchymal to epithelial (MET). Two major pregnancy-associated tissue systems that use EMT, and MET are the fetal membrane (amniochorion) amnion epithelial layer and cervical epithelial cells and will be reviewed here. EMT is often associated with localized inflammation, and it is a well-balanced process to facilitate tissue remodeling. Cyclic transition processes are important because a terminal state or the static state of EMT can cause accumulation of proinflammatory mesenchymal cells in the matrix regions of these tissues and increase localized inflammation that can cause tissue damage. Interactions that determine homeostasis are often controlled by both endocrine and paracrine mediators. Pregnancy maintenance hormone progesterone and its receptors are critical for maintaining the balance between EMT and MET. Increased intrauterine oxidative stress at term can force a static (terminal) EMT and increase inflammation that are physiologic processes that destabilize homeostasis that maintain pregnancy to promote labor and delivery of the fetus. However, conditions that can produce an untimely increase in EMT and inflammation can be pathologic. These tissue damages are often associated with adverse pregnancy complications such as preterm prelabor rupture of the membranes (pPROM) and spontaneous preterm birth (PTB). Therefore, an understanding of the biomolecular processes that maintain cyclic EMT-MET is critical to reducing the risk of pPROM and PTB. Extracellular vesicles (exosomes of 40-160 nm) that can carry various cargo are involved in cellular transitions as paracrine mediators. Exosomes can carry a variety of biomolecules as cargo. Studies specifically using exosomes from cells undergone EMT can carry a pro-inflammatory cargo and in a paracrine fashion can modify the neighboring tissue environment to cause enhancement of uterine inflammation.

Analysis of Maternal and Neonatal Outcome of Patients with Preterm Prelabor Rupture of Membranes

Background

Preterm prelabor rupture of membranes (PPROM) increases risk of maternal and neonatal diseases. Expectant treatment is one major treatment for PPROM patients, but it raises concerns on infection. Currently, the optimal delivery time for PPROM patients is still unclear, and there are various outcomes for the patients with PPROM. Previous studies conducted to analyze the pregnancy outcome showed inconsistent results. The purpose of this study is to retrospectively analyze the maternal and neonatal outcomes for comparison among different latency periods of patients with PPROM at a university hospital in China.

Method

This was a retrospective study. We divided all patients with PPROM into four groups according to gestational weeks, namely, group A (GA 24-27⁺⁶), group B (GA 28-31⁺⁶), group C (GA 32-33⁺⁶), and group D (GA34-36⁺⁶). The maternal and neonatal outcomes of each group were observed, respectively. Groups B and C were separately divided into two subgroups according to the median latency period of each group, namely, B1, B2, C1, and C2. Then, the differences of pregnancy outcomes between B1 and B2, C1 and C2, were compared, respectively. A p value < 0.05 was considered statistically significant.

Result

Group A: the common maternal and neonatal complications were the increased infection index before labour, neonatal hyperbilirubinemia and neonatal respiratory distress syndrome. Groups B, C, and D: the common maternal and neonatal complications were the increased infection index before labour, fetal distress, neonatal pneumonia, neonatal hyperbilirubinemia, and patent foramen ovale. Comparison of pregnancy outcome between group B1 and group B2 showed higher incidence rate of increased infection index before labour, lower incidence rate of respiratory distress syndrome, electrolyte disturbance, and premature brain in group B2 than those in group B1. Comparison of pregnancy outcome between group C1 and group C2 showed the higher incidence of increased infection index before labour, bigger birth weight, and shorter hospital stay in group C2 than those in group C1.

Conclusion

Increased infection index before labour was common maternal complication in four groups. Neonatal hyperbilirubinemia and neonatal pneumonia were top neonatal complications in four groups. The prolongation of latency period was beneficial to newborns of patients with gestational week at 28-31⁺⁶ weeks, while it did not benefit those with gestational week beyond 32 weeks.

Genital Mycoplasmas and Biomarkers of Inflammation and Their Association With Spontaneous Preterm Birth and Preterm Prelabor Rupture of Membranes: A Systematic Review and Meta-Analysis

Genital mycoplasmas (GM), such as Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma parvum, and Ureaplasma urealyticum are commonly associated with spontaneous preterm labor (SPTL), spontaneous preterm birth (PTB), and preterm prelabor rupture of membranes (PPROM). This study determined the association between GM and such adverse pregnancy outcomes. We searched for studies published 1980–2019 in MEDLINE, EMBASE, and Web of Science. Studies were eligible when GM was detected during pregnancy. We included 93 and 51 studies in determining the prevalence and the inflammatory biomarkers associated with GM, respectively, using the “metafor” package within R. The protocol was registered with PROSPERO (registration no. CRD42016047297). Women with the studied adverse pregnancy outcomes had significantly higher odds of presence with GM compared to women who delivered at term. For PTB, the odds ratios were: M. hominis (OR: 2.25; CI: 1.35–3.75; I²: 44%), M. genitalium (OR: 2.04; CIL 1.18–3.53; I²: 20%), U. parvum (OR: 1.75; CI: 1.47–2.07; I²: 0%), U. urealyticum (OR: 1.50; CI: 1.08–2.07; I²: 58%). SPTL had significantly higher odds with M. hominis (OR: 1.96; CI: 1.19–3.23; I²: 1%) or U. urealyticum (OR: 2.37; CI: 1.20–4.70; I²: 76%) compared to women without SPTL. Women with PPROM had significantly higher odds with M. hominis (OR: 2.09; CI: 1.42–3.08; I²: 0%) than women without PPROM. However, our subgroup analysis based on the diagnostic test and the sample used for detecting GM showed a higher prevalence of GM in maternal samples than in fetal samples. GM presence of the cervix and vagina was associated with lower odds of PTB and preterm labor (PTL). In contrast, GM presence in the AF, fetal membrane, and placenta was associated with increased odds of PTB and PTL. However, genital mycoplasmas may not elicit the massive inflammation required to trigger PTB. In conclusion, GM presence in the fetal tissues was associated with significantly increased odds of PTB and PTL.

Computational Screening of the Natural Product Osthole and Its Derivates for Anti-Inflammatory Activity

Osthole (OS) is a natural coumarin with a long history of medicinal use in a variety of diseases, such as itch and menstrual disorders. In recent years, OS has been shown to treat inflammation and reduce the expression and activity of NF-κB, although its mechanism of action is still unclear. Overexpression of inflammatory cytokines can have many negative effects in the body, including inducing preterm labor; thus, the modulation of inflammation by OS and its derivatives may be able to delay preterm birth, increasing neonatal survival rates. The objectives of this study were to screen and identify the derivatives of OS with the highest potential for binding capacity to inflammatory mediators NF-κB, TNF-α, and ERK1, and to measure the drug-like properties of these compounds. GLIDE docking in Schrodinger Maestro software was used to calculate docking scores for a variety of semi-synthetic OS derivatives against three proteins involved in inflammation: NF-κB, TNF-α, and ERK1. Schrodinger Qikprop was also used to measure the pharmaceutically relevant properties of the compounds. The protonated demethoxy osthole 1 showed the highest docking of all the proteins tested, while the deprotonated demethoxy osthole 2 consistently had the lowest scores, denoting the importance of pH in the binding activity of this derivative. The lowest docking was at NF-κB, suggesting that this is less likely to be the primary target of OS. All of the screened derivatives showed high drug potential, based on their Qikprop properties. OS and its derivatives showed potential to bind to multiple proteins that regulate the inflammatory response and are prospective candidates for delaying preterm birth.

Development of a mouse model of ascending infection and preterm birth

Background

Microbial invasion of the intraamniotic cavity and intraamniotic inflammation are factors associated with spontaneous preterm birth. Understanding the route and kinetics of infection, sites of colonization, and mechanisms of host inflammatory response is critical to reducing preterm birth risk.

Objectives

This study developed an animal model of ascending infection and preterm birth with live bacteria (E. coli) in pregnant CD-1 mice with the goal of better understanding the process of microbial invasion of the intraamniotic cavity and intraamniotic inflammation.

Study design

Multiple experiments were conducted in this study. To determine the dose of E. coli required to induce preterm birth, CD-1 mice were injected vaginally with four different doses of E. coli (10³, 10⁶, 10¹⁰, or 10¹¹ colony forming units [CFU]) in 40 μL of nutrient broth or broth alone (control) on an embryonic day (E)15. Preterm birth (defined as delivery before E18.5) was monitored using live video. E. coli ascent kinetics were measured by staining the E. coli with lipophilic tracer DiD for visualization through intact tissue with an in vivo imaging system (IVIS) after inoculation. The E. coli were also directly visualized in reproductive tissues by staining the bacteria with carboxyfluorescein succinimidyl ester (CFSE) prior to administration and via immunohistochemistry (IHC) by staining tissues with anti-E. coli antibody. Each pup’s amniotic fluid was cultured separately to determine the extent of microbial invasion of the intraamniotic cavity at different time points. Intraamniotic inflammation resulting from E. coli invasion was assessed with IHC for inflammatory markers (TLR-4, P-NF-κB) and neutrophil marker (Ly-6G) for chorioamnionitis at 6- and 24-h post-inoculation.

Results

Vaginally administered E. coli resulted in preterm birth in a dose-dependent manner with higher doses causing earlier births. In ex vivo imaging and IHC detected uterine horns proximal to the cervix had increased E. coli compared to the distal uterine horns. E. coli were detected in the uterus, fetal membranes (FM), and placenta in a time-dependent manner with 6 hr having increased intensity of E. coli positive signals in pups near the cervix and in all pups at 24 hr. Similarly, E. coli grew from the cultures of amniotic fluid collected nearest to the cervix, but not from the more distal samples at 6 hr post-inoculation. At 24 hr, all amniotic fluid cultures regardless of distance from the cervix, were positive for E. coli. TLR-4 and P-NF-κB signals were more intense in the tissues where E. coli was present (placenta, FM and uterus), displaying a similar trend toward increased signal in proximal gestational sacs compared to distal at 6 hr. Ly-6G+ cells, used to confirm chorioamnionitis, were increased at 24 hr compared to 6 hr post-inoculation and control.

Conclusion

We report the development of mouse model of ascending infection and the associated inflammation of preterm birth. Clinically, these models can help to understand mechanisms of infection associated preterm birth, determine targets for intervention, or identify potential biomarkers that can predict a high-risk pregnancy status early in pregnancy.

Pregnancy complicated with hepatitis B virus infection and preterm birth: a retrospective cohort study

Background

We aimed to investigate whether maternal chronic hepatitis B virus (HBV) infection affects preterm birth (PTB) in pregnant women.

Methods

We retrospectively analyzed HBV-infected and non-infected pregnant women attending antenatal care at Fujian Maternity and Child Health Hospital, Fuzhou, China between January 1, 2016 to December 31, 2018. Participants were divided into HBV infection (n = 1302) and control (n = 12,813) groups. We compared baseline data, pregnancy and perinatal complications, and preterm delivery outcomes between groups. Performed multiple logistics regression analysis to adjust for confounding factors. Finally, we compared early PTB outcome between different HBV DNA level groups.

Results

The incidence of preterm birth (gestation less than 37 weeks) was similar between the groups, early preterm birth (gestation less than 34 weeks) were significantly more among the HBV infection group than among the controls (1.6% VS. 0.8%; P = 0.003). After adjusting for confounding factors through logistics regression, HBV infection was found to be an independent early PTB risk factor gestation (adjusted odds ratio 1.770; 95% confidence interval [1.046–2.997]). The incidence of early PTB in < 500 group, 500 ~ 2.0 × 10e⁵ group and > 2.0 × 10e⁵ group was not statistically significant (P = 0.417).

Conclusion

HBV infection is an independent risk factor for early PTB, and the risk did not seem to be influenced by the levels of HBV DNA. Comprehensive programs focusing on pregnant women with HBV infection would reduce the incidence of adverse outcomes.

Landscape of Preterm Birth Therapeutics and a Path Forward

Preterm birth (PTB) remains the leading cause of infant morbidity and mortality. Despite 50 years of research, therapeutic options are limited and many lack clear efficacy. Tocolytic agents are drugs that briefly delay PTB, typically to allow antenatal corticosteroid administration for accelerating fetal lung maturity or to transfer patients to high-level care facilities. Globally, there is an unmet need for better tocolytic agents, particularly in low- and middle-income countries. Although most tocolytics, such as betamimetics and indomethacin, suppress downstream mediators of the parturition pathway, newer therapeutics are being designed to selectively target inflammatory checkpoints with the goal of providing broader and more effective tocolysis. However, the relatively small market for new PTB therapeutics and formidable regulatory hurdles have led to minimal pharmaceutical interest and a stagnant drug pipeline. In this review, we present the current landscape of PTB therapeutics, assessing the history of drug development, mechanisms of action, adverse effects, and the updated literature on drug efficacy. We also review the regulatory hurdles and other obstacles impairing novel tocolytic development. Ultimately, we present possible steps to expedite drug development and meet the growing need for effective preterm birth therapeutics.

Association of vitamin D and gene variants in the vitamin D metabolic pathway with preterm birth

OBJECTIVES

The aim of this study was to explore the association of vitamin D (VitD) levels during pregnancy and its metabolic pathway genes with the risk for preterm birth (PTB) among pregnant women in southeast China.

METHODS

This study was conducted in Zhoushan Maternal and Child Health Hospital, Zhejiang, from August 2011 to May 2018. Plasma 25-hydroxyvitamin vitamin D [25(OH)D] levels in three trimesters and single-nucleotide morphisms in the VitD metabolic pathway were measured. Relevant information was collected using questionnaires and an electronic medical recorder system. Multiple statistical methods including linear regression, logistic regression, and crossover analysis were applied.

RESULTS

The prospective cohort study included 3465 pregnant women, of which 202 were PTB (week of gestation at delivery: 33.38 ± 4.05), accounting for 5.8%. After adjusting for potential confounders, VitD sufficiency (≥30 ng/mL) in the second and third trimesters was associated with longer gestational age at delivery compared with VitD deficiency (<20 ng/mL). However, no significant association was found between VitD with the risk for PTB. rs7041, rs10210408, and rs2228171 were associated with gestational week and the risk for PTB. Significant associations were found of rs10210408, rs2209314, rs1155563, rs2544381 and the status of VitD in the second and third trimester with the gestational week. We also found that rs7041 and VitD in the second trimester might exert interaction on gestational week and the risk for PTB (P_inter = 0.038; P_inter = 0.019); rs16846876 and VitD in the second trimester might exert interaction on gestational week (P_inter = 0.024); rs4334089 and VitD in the third trimester might exert interaction on gestational week (P_inter = 0.024). Similar results were found when we tested pregnant women's plasma 25(OH)D in the first and second trimesters.

CONCLUSIONS

Women with VitD deficiency were associated with shorter gestational weeks. Single-nucleotide morphisms in VitD metabolic pathway genes were significantly associated with gestation week and the risk for PTB, mainly in vitamin D-binding protein (GC) and low-density lipoprotein-related protein 2 (LRP2)genes. Additionally, maternal VitD with GC gene and maternal VitD with vitamin D receptor (VDR) gene might exert interactions on the risk for PTB.

Predictors of persistent and changing developmental problems of preterm children

BACKGROUND

Accurate prediction of persistent and emerging developmental problems in preterm-born children may lead to targeted interventions.

AIMS

To determine whether specific perinatal and social factors were associated with persistent, emerging, and resolving developmental problems of early-preterm (EPs) and moderately-and-late-preterm children (MLPs) from before to after school entry.

STUDY DESIGN

Observational longitudinal cohort study, part of the LOLLIPOP cohort-study.

SUBJECTS

341 EPs and 565 MLPs.

OUTCOME MEASURES

Developmental problems using the Ages and Stages Questionnaire at ages 4 and 5. We collected data on perinatal and social factors from medical records. Using logistic regression analyses we assessed associations between 48 factors and persistent, emerging, and resolving problems.

RESULTS

Of EPs, 8.7% had persistent and 5.1% emerging problems; this was 4.3% and 1.9% for MLPs, respectively. Predictors for persistent problems included chronic mental illness of the mother, odds ratio (95% confidence interval) 8.01 (1.85-34.60), male sex 4.96 (2.28-10.82), being born small-for-gestational age (SGA) 2.39 (1.15-4.99), and multiparity 3.56 (1.87-6.76). Predictors for emerging problems included MLP birth with prolonged premature rupture of membranes (PPROM) 5.01 (1.38-18.14). Including all predictors in a single prediction model, the explained variance (Nagelkerke R²) was 21.9%, whereas this was 3.0% with only EP/MLP birth as predictor.

CONCLUSIONS

Only few perinatal and social factors had associations with persistent and emerging developmental problems for both EPs and MLPs. For children with specific neonatal conditions such as SGA, and PPROM in MLPs, problems may persist. Insight in risk factors largely improved the prediction of developmental problems among preterm children.

Measurement of the Uterocervical Angle for Predicting the Latent Period in Pregnancy Exhibiting Premature Membrane Rupture

OBJECTIVES

The duration of the latent period is uncertain in preterm premature rupture of membranes (PPROM). This time estimate provides information on the time of the corticosteroid to be applied and the time of delivery of the pregnant women. Here, we used transvaginal sonography to determine the relationship between the uterocervical angle (UCA) and PPROM latency and the risk for neonatal complications.

DESIGN

This is a prospective cohort study of 80 singleton pregnancies with PPROM. Participants/Materials, Setting, and Methods: This prospective cohort study was conducted at a tertiary center with a total of 80 singleton pregnancies with PPROM. The UCA and cervical length were measured in the first evaluation of PPROM in patients between 24 and 34 weeks of age. The study population was subdivided into 2 groups: group 1 (n = 27) included women who gave birth within 10 days after a PPROM diagnosis and group 2 (n = 53) included women who gave birth later than this. Our aim was latency prediction (more or less than 10 days) in PPROM patients undergoing regular UCA monitoring.

RESULTS

Of the women in group 1, 74.1% (n = 20) had spontaneous births and 7.4% (n = 2) had induced births because of clinical chorioamnionitis. Of the women in group 2, 71.6% (n = 38) had spontaneous births and 7.6% (n = 4) had induced births because of clinical chorioamnionitis (n = 3) or poor fetal condition (n = 1). We drew receiver operating characteristic curves to explore whether the UCA predicted birth within 10 days of PPROM. The area under the curve was 0.894 (p < 0.001). The optimal UCA cutoff was 108°, with 93% sensitivity and 85% specificity.

LIMITATIONS

First, the sample size was small; it would have been better to have more patients. Second, we measured the UCA only once. Third, patients were not categorized by parity.

CONCLUSIONS

The UCA, measured by the transvaginal route, can successfully predict latent period in PPROM. Measuring the UCA can be useful to determine the time of corticosteroid administration and to inform patients about the time of birth.

Diseases and conditions that impact maternal and fetal health and the potential for nanomedicine therapies

Maternal mortality rates in the United States have steadily increased since 1987 to the current rate of over 16 deaths per 100,000 live births. Whereas most of these deaths are related to an underlying condition, such as cardiovascular disease, many pregnant women die from diseases that emerge as a consequence of pregnancy. Both pre-existing and emergent diseases and conditions are difficult to treat in pregnant women because of the potential harmful effects of the treatment on the developing fetus. Often the health of the woman and the health of the baby are at odds and must be weighed against each other when medical treatment is needed, frequently leading to iatrogenic preterm birth. However, the use of engineered nanomedicines has the potential to fill the treatment gap for pregnant women. This review describes several conditions that may afflict pregnant women and fetuses and introduces how engineered nanomedicines may be used to treat these illnesses. Although the field of maternal-fetal nanomedicine is in its infancy, with additional research and development, engineered nanotherapeutics may greatly improve outcomes for pregnant women and their offspring in the future.

Association between prenatal rare earth elements exposure and premature rupture of membranes: Results from a birth cohort study

BACKGROUND

The widespread exploitation and application of rare earth elements (REE) have led to the risk of human exposure and might result in the adverse health effect on pregnant women. However, no epidemiological studies have explored the associations between prenatal REE exposure and premature rupture of membranes (PROM).

OBJECTIVE

We aimed to investigate the associations of maternal urinary REE levels with the risk of PROM.

METHODS

A total of 4897 mother-newborn pairs were recruited from a birth cohort study in Wuhan, China. Urinary concentrations of REE were measured by inductively coupled plasma mass spectrometry (ICP-MS). The associations of prenatal REE exposure with PROM were evaluated using logistic regression models. False discovery rate (FDR) was applied to adjust for multiple testing. Weighted quantile sum (WQS) regression was used to estimate the association of urinary REE mixture with PROM.

RESULTS

With one unit increase (μg/g creatinine) in natural log-transformed urinary REE levels (Ce, Yb, La, Pr, Nd, Eu, Gd, Dy, Ho, Er, Tm), the adjusted ORs (95% CIs) for the PROM were from 1.143 (1.078, 1.211) to 1.317 (1.223, 1.419), and the associations were still observed after FDR adjustment (all P_FDRs < 0.05). The associations were stronger among male infants than female infants. Furthermore, the urinary REE mixture was also associated with the risk of PROM, a quartile increase in the WQS index of REE resulted in ORs (95% CI) for the PROM of 1.494 (1.356, 1.645) in the adjusted model.

CONCLUSIONS

Our findings suggested that prenatal exposure to REE (Ce, Yb, La, Pr, Nd, Eu, Gd, Dy, Ho, Er, and Tm) and REE mixture were associated with the increased risk of PROM. Further studies from different populations are needed to confirm the associations and to explore the mechanisms.

Periodontal disease and preterm birth: Findings from the 2015 Pelotas birth cohort study

OBJECTIVES

To verify the association between periodontal conditions and preterm birth.

MATERIALS AND METHODS

This study used data from the 2015 Pelotas Birth Cohort Study, Brazil. Pregnant women expected to give birth in 2015 were interviewed and dentally examined by a trained dentist, with periodontal measures collected in all teeth, six sites per tooth. Exposure was periodontal disease. Outcomes were preterm birth (all births <37 weeks of gestational age) and early preterm birth (<34 weeks). Analysis was carried out using Poisson regression according to a directed acyclic graph.

RESULTS

A total of 2,474 women participated in the study. Incidence of preterm births was 10.2% and of early preterm births was 3.5%. Frequency of gingivitis was 21.7%, and periodontitis was 14.9%. Periodontitis was associated with a risk almost two times higher of having early preterm delivery compared with healthy pregnant women (RR 1.93; 95% CI 1.09-3.43). Presence of 5+ mm periodontal pocket with bleeding on probing was also associated with higher risk for early preterm delivery.

CONCLUSIONS

The association between periodontal disease in pregnancy and the occurrence of preterm delivery is sensitive to the case definitions. Periodontal disease increased the risk of early preterm delivery.

Modeling ascending infection with a feto-maternal interface organ-on-chip

Maternal infection (i.e., ascending infection) and the resulting host inflammatory response are risk factors associated with spontaneous preterm birth (PTB), a major pregnancy complication. However, the path of infection and its propagation from the maternal side to the fetal side have been difficult to study due to the lack of appropriate in vitro models and limitations of animal models. A better understanding of the propagation kinetics of infectious agents and development of the host inflammatory response at the feto-maternal (amniochorion-decidua, respectively) interface (FMi) is critical in curtailing host inflammatory responses that can lead to PTB. To model ascending infection and determine inflammatory responses at the FMi, we developed a microfluidic organ-on-chip (OOC) device containing primary cells from the FMi (decidua, chorion, and amnion [mesenchyme and epithelium]) and collagen matrix harvested from primary tissue. The FMi-OOC is composed of four concentric circular cell/collagen chambers designed to mimic the thickness and cell density of the FMi in vivo. Each layer is connected by arrays of microchannels filled with type IV collagen to recreate the basement membrane of the amniochorion. Cellular characteristics (viability, morphology, production of nascent collagen, cellular transitions, and migration) in the OOC were similar to those seen in utero, validating the physiological relevance and utility of the developed FMi-OOC. The ascending infection model of the FMi-OOC, triggered by exposing the maternal (decidua) side of the OOC to lipopolysaccharide (LPS, 100 ng mL-1), shows that LPS propagated through the chorion, amnion mesenchyme, and reached the fetal amnion within 72 h. LPS induced time-dependent and cell-type-specific pro-inflammatory cytokine production (24 h decidua: IL-6, 48 h chorion: GM-CSF and IL-6, and 72 h amnion mesenchyme and epithelium: GM-CSF and IL-6). Collectively, this OOC model and study successfully modeled ascending infection, its propagation, and distinct inflammatory response at the FMi indicative of pathologic pathways of PTB. This OOC model provides a novel platform to study physiological and pathological cell status at the FMi, and is expected to have broad utility in the field of obstetrics.

Novel Insights into the Regulatory Role of Nuclear Factor (Erythroid-Derived 2)-Like 2 in Oxidative Stress and Inflammation of Human Fetal Membranes

Fetal membrane dysfunction in response to oxidative stress (OS) is associated with adverse pregnancy outcomes. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is one of the regulators of innate OS response. This study evaluated changes in Nrf2 expression and its downstream targets heme oxygenase (HO-1) and peroxisome proliferator-activated receptor gamma (PPARγ) in fetal membranes during OS and infection in vitro. Furthermore, we tested the roles of sulforaphane (SFN; an extract from cruciferous vegetables) and trigonelline (TRN; an aromatic compound in coffee) in regulating Nrf2 and its targets. Fetal membranes (n = 6) collected at term were placed in an organ explant system were treated with water-soluble cigarette smoke extract (CSE), an OS inducer (1:10), and lipopolysaccharide (LPS; 100 ng/mL). Nrf2 expression, expression, its enhancement by sulforaphane (SFN, 10 µM/mL) and down regulation by TRN (10uM/mL) was determined by western blots. Expression of Nrf2 response elements PPARγ (western) heme oxygenase (HO-1), and IL-6 were quantified by ELISA. CSE and LPS treatment of fetal membranes increased nrf2, but reduced HO-1 and PPARγ and increased IL-6. Co-treatment of SFN, but not with TRN, with CSE and LPS increased Nrf2 substantially, as well as increased HO-1 and PPARγ and reduced IL-6 expression. Risk factor-induced Nrf2 increase is insufficient to generate an antioxidant response in fetal membranes. Sulforaphane may enhance innate antioxidant and anti-inflammatory capacity by increasing NRF-2 expression.

IL-37 Exerts Anti-Inflammatory Effects in Fetal Membranes of Spontaneous Preterm Birth via the NF-κB and IL-6/STAT3 Signaling Pathway

Spontaneous preterm birth (sPTB), defined as delivery before 37 weeks of gestation, is thought to be a multifactorial syndrome. However, the inflammatory imbalance at the maternal-fetal interface promotes excessive secretion of inflammatory factors and induces apoptosis and degradation of the extracellular matrix (ECM), which can subsequently lead to preterm birth. As an anti-inflammatory molecule in the IL-1 family, interleukin-37 (IL-37) mainly plays an inhibiting role in a variety of inflammatory diseases. However, as a typical inflammatory disease, no previous studies have been carried out to explore the role of IL-37 in sPTB. In this study, a series of molecular biological experiments were performed in clinical samples and human amniotic epithelial cell line (Wistar Institute Susan Hayflick (WISH)) to investigate the deficiency role of IL-37 and the potential mechanism. Firstly, the results indicated that the expression of IL-37 in human peripheral plasma and fetal membranes was significantly decreased in the sPTB group. Afterward, it is proved that IL-37 could significantly suppress the production of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in WISH cells. Simultaneously, once silence IL-37, LPS-induced apoptosis and activity of matrix metalloproteinases (MMPs) 2 and 9 were significantly increased. In addition, the western blot data showed that IL-37 performed its biological effects by inhibiting the NF-κB and IL-6/STAT3 pathway. In conclusion, our results suggest that IL-37 limits excessive inflammation and subsequently inhibits ECM remodeling and apoptosis through the NF-κB and IL-6/STAT3 signaling pathway in the fetal membranes.

Systemic Inflammation in Pregnant Women With Periodontitis and Preterm Prelabor Rupture of Membranes: A Prospective Case-Control Study

Aims: Periodontal disease is associated with adverse pregnancy outcome, but the underlying pathophysiologic mechanism is still unknown. In this prospective, longitudinal, non-interventional case-control study, 45 women with preterm premature rupture of membranes and 26 controls with uncomplicated pregnancies were examined at three time-points (T1: 20–34 weeks of gestations; T2: within 48 h after delivery; T3: 4–6 weeks post partum). Examinations included subgingival, blood, vaginal, and placenta sampling for microbiologic, cytokine, and histology assessment. Objective of this study was to test the hypothesis that systemic inflammatory changes and not specific bacteria are predominantly involved in the association between periodontal disease and adverse pregnancy outcome.

Results: Demographic data and gestational age at T1 were comparable between groups. While there was no correlation between vaginal and gingival fluid microbiome, cytokine levels in the assessed compartments differed between cases, and controls. Vaginal smears did not show a higher rate of abnormal flora in the cases at the onset of preterm premature rupture of membranes. Number and variety of bacteria in the case group placental membranes and vagina were higher, but these bacteria were not found in membranes at birth.

Conclusions: On the basis of our results we speculate that an inflammatory pathway sequentially involving periodontal tissue, maternal serum, and finally vaginal compartment contributes to the underlying pathomechanism involved in preterm premature rupture of membranes associated with periodontitis.

Is there a role for placental histopathology in predicting the recurrence of preterm birth?

PURPOSE

Spontaneous preterm birth (sPTB) is a major cause of neonatal morbidity and mortality with a relatively high rate to recurrence. Our aim was to study the role of placental histopathology in predicting recurrence of sPTB.

METHODS

We conducted a retrospective cohort study. The medical records and placental pathologic reports of all women with sPTB (gestational age 23^0/7-36^6/7 weeks), during 2008-2015, were reviewed. Only women who had a subsequent delivery were included. Multiple pregnancies and women with known uterine anomalies were excluded. Placental histopathology lesions were classified into maternal and fetal vascular malperfusion lesions, acute maternal and fetal inflammatory responses lesions, and chronic inflammatory lesions. Placental lesions were compared between patients with and without recurrent sPTB on their subsequent pregnancies.

RESULTS

Maternal characteristics, gestational age, birthweight, and the rate of preterm rupture of membrane at index delivery were similar between the recurrent sPTB (n = 72) and the non-recurrent sPTB (n = 167) groups. The incidence of placental vascular malperfusion lesions, or inflammatory lesions did not differ between the study groups. However, on multivariate logistic regression analysis, the presence of only acute inflammatory response lesions was associated with recurrence of early sPTB ( < 34 weeks) (adjusted OR 3.16; 95% CI 1.22-8.18).

CONCLUSION

The presence of isolated placental acute maternal or fetal inflammatory response in index sPTB may be associated with recurrence of early sPTB.

Fracture toughness of human amniotic membranes

Amnion is a membrane that surrounds and structurally protects the developing fetus during pregnancy. The rupture of amniotic membranes prior to both normal and preterm deliveries involves stretch forces acting on a biochemically triggered weak zone of the membranes. Fracture toughness is an important mechanical property describing how the membranes containing a defect resist fracture, but this property has never been investigated in amniotic membranes. In this work, the fracture toughness of many samples cut from four pieces of amniotic membrane from different mothers was examined by uniaxial and pure shear (mode I) fracture tests. The measurement was checked for dependence on the sample geometry and notch length. Results from the uniaxial tensile test show J-shaped stress-strain curves and confirm that the amniotic membrane is a nonlinear material. The measured fracture toughness of four amniotic membranes ranged from 0.96 ± 0.11 to 1.83 ± 0.18 kJ m^-2. Despite considering the effect of the presence of the defect on mechanical property measurement, similar fracture behaviour was observed for pre-notched and unnotched specimens, indicating that the membranes were extremely tolerant to defects. This defect-tolerant characteristic provides insight into the understanding of fetal membrane rupture.

Activation of the epithelial sodium channel (ENaC) leads to cytokine profile shift to pro-inflammatory in labor

The shift of cytokine profile from anti‐ to pro‐inflammatory is the most recognizable sign of labor, although the underlying mechanism remains elusive. Here, we report that the epithelial sodium channel (ENaC) is upregulated and activated in the uterus at labor in mice. Mechanical activation of ENaC results in phosphorylation of CREB and upregulation of pro‐inflammatory cytokines as well as COX‐2/PGE₂ in uterine epithelial cells. ENaC expression is also upregulated in mice with RU486‐induced preterm labor as well as in women with preterm labor. Interference with ENaC attenuates mechanically stimulated uterine contractions and significantly delays the RU486‐induced preterm labor in mice. Analysis of a human transcriptome database for maternal–fetus tissue/blood collected at onset of human term and preterm births reveals significant and positive correlation of ENaC with labor‐associated pro‐inflammatory factors in labored birth groups (both term and preterm), but not in non‐labored birth groups. Taken together, the present finding reveals a pro‐inflammatory role of ENaC in labor at term and preterm, suggesting it as a potential target for the prevention and treatment of preterm labor.

A high concentration of fetal fibronectin in cervical secretions increases the risk of intra-amniotic infection and inflammation in patients with preterm labor and intact membranes

Objective To determine whether the risk of intra-amniotic infection/inflammation and spontaneous preterm delivery (SPTD) varies as a function of the concentration of cervical fetal fibronectin (fFN) in patients with preterm labor and intact membranes. Methods This prospective study included 180 patients with preterm labor and intact membranes who had a sample collected for quantitative fFN measurement and underwent amniocentesis. Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas. Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. Results (1) The prevalence of intra-amniotic infection/inflammation and SPTD within 7 days was 32.2% (58/180) and 33.9% (61/178), respectively; (2) The higher the fFN concentration, the greater the risk of intra-amniotic infection/inflammation and SPTD within 7 days (P<0.001, respectively); (3) An fFN concentration 150 ng/mL had a better diagnostic performance than an fFN 50 ng/mL in the identification of intra-amniotic infection/inflammation and SPTD within 7 days; (4) Among the patients with an fFN <50 ng/mL, intra-amniotic infection/inflammation was identified in 7.6% (6/79) of patients and 66.7% (4/6) delivered within 7 days. Conclusion The higher the concentration of fFN, the greater the risk of intra-amniotic infection/inflammation and SPTD in patients with preterm labor and intact membranes.

Pregnancy outcomes of antibody negative and untreated subclinical hypothyroidism

AIM

Subclinical hypothyroidism is thought to be associated with adverse pregnancy outcomes but the data is conflicting and generally depends on antibody positivity and treatment. We evaluated the pregnancy outcomes in Turkish population with untreated, antibody negative subclinical hypothyroidism for the first time.

METHODS

We searched for 30 015 patients between January 2016 and May 2017 retrospectively. Finally, a total of 930 pregnant women with untreated, antibody negative subclinical hypothyroidism and 7986 controls were included. Demographic characteristics, laboratory findings and pregnancy outcomes, including pregnancy loss, impaired glucose tolerance, gestational diabetes, hypertensive disorders of pregnancy, preterm birth, neonatal intensive care unit admission, placenta previa and abruption, cesarean delivery, low birthweight, Apgar score <7 and premature rupture of membranes were recorded.

RESULTS

Demographic and laboratory characteristics were similar between two groups except thyroid stimulating hormone levels and previous uterine surgery rates. Subclinical hypothyroidism group had an increased risk of pregnancy loss (odds ratio [OR] 2.583; 95% confidence interval [CI] 1.982-3.365; P < 0.001), impaired glucose tolerance (OR 1.952; 95% CI 1.450-2.627; P < 0.001), hypertensive disorders of pregnancy (OR 1.476; 95% CI 1.113-1.923; P = 0.004), neonatal intensive care unit admission (OR 1.620; 95% CI 1.084-2.420; P = 0.019), placenta previa (OR 12.581; 95% CI 5.046-31.363; P < 0.001) and cesarean delivery (OR 1.263; 95% CI 1.091-1.462; P = 0.002).

CONCLUSION

Subclinical hypothyroidism has worse pregnancy outcomes as compared to euthyroid pregnant women even in antibody negativity. Therefore, we suggest that all pregnant women should routinely be screened in their first antenatal visits for thyroid functions.

Block of Granulocyte-Macrophage Colony-Stimulating Factor Prevents Inflammation-Induced Preterm Birth in a Mouse Model for Parturition

OBJECTIVE

A multitude of factors promotes inflammation in the reproductive tract leading to preterm birth. Macrophages peak in the cervix prior to birth and their numbers are increased by the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF). We hypothesize GM-CSF is produced from multiple sites in the genital tract and is a key mediator in preterm birth.

STUDY DESIGN

Ectocervical, endocervical, and amniotic fluid mesenchymal stem cells were treated with lipopolysaccharide (LPS), and the concentration and expression of GM-CSF was measured. Pregnant CD-1 mice on gestational day 17 received LPS and an intravenous injection of either anti-mouse GM-CSF or control antibody. After 6 hours, the preterm birth rate was recorded.

RESULTS

Treatment with LPS increased the GM-CSF concentration and messenger RNA expression after 24 hours in all 3 cell lines ( P < .01). Mice treated with LPS and the GM-CSF antibody had a preterm birth rate of 25%, compared to a 66.7% preterm birth rate in controls, within 6 hours ( P < .05, χ²). Treatment with the anti-mouse GM-CSF antibody decreased the concentration of GM-CSF in the mouse serum ( P < .01) but did not alter the number of macrophages or collagen content in the cervix.

CONCLUSION

These studies demonstrate that GM-CSF is produced from multiple sites in the genital tract and that treatment with an antibody to GM-CSF prevents preterm birth. Curiously, the anti-mouse GM-CSF antibody did not decrease the number of macrophages in the cervix. Further research is needed to determine whether antibodies to GM-CSF can be utilized as a therapeutic agent to prevent preterm birth.

Cerclage is associated with the increased risk of preterm birth in women who had cervical conization

Background

The aim of this study was to determine the effect of cerclage in women who underwent cervical conization.

Methods

Study data were collected from the Korea National Health Insurance Claims Database of the Health Insurance Review and Assessment Service for 2009–2013. Women who had a conization in 2009 and a subsequent first delivery between 2009 and 2013 in Korea were enrolled.

Results

Among the women who had conization in 2009, 1075 women had their first delivery between 2009 and 2013. A cerclage was placed in 161 of the women who were treated by conization. The rate of preterm birth was higher in the women who were treated with cerclage following a conization compared with those without cerclage (10.56 vs 4.27, p < 0.01, respectively). The multivariate regression analysis revealed that the women who were treated cerclage following a conization had an increased risk of preterm delivery compared with women without cerclage (odds ratio (OR), 2.6, 95% confidence interval (CI), 1.4–4.9).

Conclusion

Our study showed that cerclage associated with an increased risk of preterm birth and preterm premature rupture of membranes in women who underwent conization. Further studies are required to clarify the mechanism by which cerclage affects the risk of preterm birth.

Mid-gestational changes in cervicovaginal fluid cytokine levels in asymptomatic pregnant women are predictive markers of inflammation-associated spontaneous preterm birth

OBJECTIVES

Perturbation of the choriodecidual space before the onset of spontaneous preterm birth (sPTB) could lead to a concomitant rise in both cervicovaginal fluid (CVF) cytokine and fetal fibronectin (FFN), and assessing the concentrations of both markers could improve the prediction of sPTB (delivery before 37 completed weeks of gestation). Therefore, we prospectively determined mid-trimester changes in CVF cytokine and FFN concentrations, and their predictive capacity for sPTB in asymptomatic pregnant women.

STUDY DESIGN

CVF collected at 20+0-22+6 weeks (n = 47: Preterm-delivered = 22, Term-delivered = 25) and 26+0-28+6 weeks (n = 50: Preterm-delivered = 17, Term-delivered = 33) from 63 asymptomatic pregnant women at risk of sPTB were examined. Cytokine and FFN concentrations were determined by multiplexed bead-based immunoassay and 10Q Rapid analysis (Hologic, MA, USA) respectively. The 20+0-22+6/26+0-28+6 weeks ratios of cytokines and FFN concentrations were compared between preterm- and term-delivered women using Receiver Operating Characteristics curves to predict sPTB. Also, bacterial 16S rDNA from 64 samples (20+0-22+6 weeks n = 36, 26+0-28+6 weeks n = 28) was amplified by polymerase chain reaction to determine associations between vaginal microflora, cytokine and FFN concentrations.

RESULTS

Changes in RANTES and IL-1β concentrations between 20+0-22+6 and 26+0-28+6 weeks, expressed as a ratios, were predictive of sPTB, RANTES (AUC = 0.82, CI = 0.62-0.94) more so than IL-1β (AUC = 0.71, CI = 0.53-0.85) and FFN (not predictive). Combining these markers (AUC = 0.83, CI = 0.63-0.95) showed similar predictive capacity as RANTES alone. FFN concentrations at 26+0-28+6 weeks correlated with IL-1β (r = 0.4, P = 0.002) and RANTES (r = 0.3, P = 0.03). In addition, there was increased prevalence of vaginal anaerobes including Bacteroides, Fusobacterium and Mobiluncus between gestational time points in women who experienced sPTB compared to the term women (P = 0.0006).

CONCLUSIONS

CVF RANTES and IL-1β in mid-trimester of pregnancy correlate with quantitative FFN. The levels of CVF RANTES and IL-1β decline significantly in women who deliver at term unlike women who deliver preterm. This observation suggests that sPTB may be characterised by sustained choriodecidual inflammation and may have clinical value in serial screening for sPTB if confirmed by larger studies.

Patterns of Systemic and Cervicovaginal Fluid Inflammatory Cytokines throughout Pregnancy

OBJECTIVE

 This study describes the normal variations in serum and cervicovaginal fluid (CVF) cytokine levels throughout pregnancy.

STUDY DESIGN

 This multicenter, prospective study examined trimester-specific maternal serum and CVF cytokines (interleukin [IL]-1α, IL-1β, IL-6, IL-8, IL-10, tumor necrosis factor-α, and C-reactive protein [CRP]). A two-factor linear mixed modeling approach compared cytokine distribution, while pairwise comparisons evaluated differences over time.

RESULTS

 Trimester-specific serum cytokine data were available for 288, 243, and 221 patients, whereas CVF cytokine data were available for 273, 229, and 198 patients. CVF had significantly higher concentrations of IL-1α, IL-1β, IL-6, IL-8, and matrix metalloproteinase-8 (p < 0.001), irrespective of the trimester. At all time points, IL-10 and CRP concentrations were higher in serum than CVF (p < 0.001). Serum IL-10 increased significantly throughout pregnancy (p < 0.001).

CONCLUSION

 Differences in cytokine distribution across different biological fluids are evident throughout pregnancy. These findings provide a framework for examining patterns of changes in cytokines throughout pregnancy.

Maternal serum advanced glycation end products level as an early marker for predicting preterm labor/PPROM: a prospective preliminary study

OBJECTIVE

To evaluate the value of maternal serum advanced glycation end products (AGEs) level at 11-13 weeks' gestation for the prediction of preterm labor and or preterm premature rupture of membranes (PPROM).

MATERIALS AND METHODS

This prospective cross-sectional study is performed in a university-affiliated hospital between February and April 2016. The participants of this study are low-risk pregnant women. Blood samples for maternal AGEs level were collected in the first trimester of pregnancy and all women completed their antenatal follow-up and delivered in our center. During the follow-up 21 women developed preterm labor/PPROM. The first trimester maternal AGEs levels of preterm labor/PPROM cases were compared with uncomplicated cases (n = 25) matched for age-parity and BMI. The predictive value of AGEs levels for preterm labor/PPROM was also assessed.

RESULTS

First-trimester AGEs levels were significantly higher in cases complicated with preterm labor/PPROM (1832 (415-6682) versus 1276 (466-6445) ng/L, p = .001 and 1722 (804-6682) versus 1343 (466-6445) ng/L, p = .025). According to receiver-operating characteristic curve analysis, the calculated cut off value of AGEs was 1538 ng/L with the sensitivity 91.7%, specificity 73.8%; and the negative and positive predictive values were 91.6% and 29.5%, respectively.

CONCLUSIONS

For the prediction of preterm labor/PPROM, the relatively high AGEs levels in the first trimester might be a useful marker.

Inhibition of PIM1 kinase attenuates inflammation-induced pro-labour mediators in human foetal membranes in vitro

STUDY QUESTION

Does proviral integration site for Moloney murine leukaemic virus (PIM)1 kinase play a role in regulating the inflammatory processes of human labour and delivery?

SUMMARY ANSWER

PIM1 kinase plays a critical role in foetal membranes in regulating pro-inflammatory and pro-labour mediators.

WHAT IS KNOWN ALREADY

Infection and inflammation have strong causal links to preterm delivery by stimulating pro-inflammatory cytokines and collagen degrading enzymes, which can lead to rupture of membranes. PIM1 has been shown to have a role in immune regulation and inflammation in non-gestational tissues; however, its role has not been explored in the field of human labour.

STUDY DESIGN, SIZE, DURATION

PIM1 expression was analysed in myometrium and/or foetal membranes obtained at term and preterm (n = 8-9 patients per group). Foetal membranes, freshly isolated amnion cells and primary myometrial cells were used to investigate the effect of PIM1 inhibition on pro-labour mediators (n = 5 patients per treatment group).

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Foetal membranes, from term and preterm, were obtained from non-labouring and labouring women, and from preterm pre-labour rupture of membranes (PPROM) (n = 9 per group). Amnion was collected from women with and without preterm chorioamnionitis (n = 8 per group). Expression of PIM1 kinase was determined by qRT-PCR and western blotting. To determine the effect of PIM1 kinase inhibition on the expression of pro-inflammatory and pro-labour mediators induced by bacterial products lipopolysaccharide (LPS) (10 μg/ml) and flagellin (1 μg/ml) and pro-inflammatory cytokine tumour necrosis factor (TNF) (10 ng/ml), chemical inhibitors SMI-4a (20 μM) and AZD1208 (50 μM) were used in foetal membrane explants and siRNA against PIM1 was used in primary amnion cells. Statistical significance was set at P < 0.05.

MAIN RESULTS AND THE ROLE OF CHANCE

PIM1 expression was significantly increased in foetal membranes after spontaneous term labour compared to no labour at term and in amnion with preterm chorioamnionitis compared to preterm with no chorioamnionitis. There was no change in PIM1 expression with preterm labour or PPROM compared to preterm with no labour or PPROM. In human foetal membranes, PIM1 inhibitors SMI-4a and AZD1208 significantly decreased the expression of pro-inflammatory cytokine interleukin-6 (IL6) and chemokines CXCL8 and CCL2 mRNA and release, prostaglandin prostaglandin F2α (PGF2α) release, adhesion molecule intercellular adhesion molecule 1 mRNA expression and release, and oxidative stress marker 8-isoprostane release after stimulation with either LPS or flagellin. Primary amnion cells transfected with PIM1 siRNA also showed decreased expression of IL6, CXCL8 and CCL2, PTGS2 mRNA and PGF2α release, and matrix metalloproteinase-9 (MMP9) expression, when stimulated with TNF.

LARGE SCALE DATA

None.

LIMITATIONS, REASONS FOR CAUTION

The conclusions were drawn from in vitro experiments using foetal membrane explants and primary cells isolated from amnion. Animal models are necessary to determine whether PIM1 kinase inhibitors can prevent spontaneous preterm birth in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

PIM1 kinase inhibitors may provide a novel therapeutic approach for preventing spontaneous preterm birth.

STUDY FUNDING/COMPETING INTEREST(S)

Associate Professor Martha Lappas is supported by a Career Development Fellowship from the National Health and Medical Research Council (NHMRC; grant no. 1047025). Funding for this study was provided by the NHMRC (grant no. 1058786), Norman Beischer Medical Research Foundation and the Mercy Research Foundation. The authors have no conflict of interest.

Timing of probiotic milk consumption during pregnancy and effects on the incidence of preeclampsia and preterm delivery: a prospective observational cohort study in Norway

OBJECTIVES

To investigate whether the timing of probiotic milk intake before, during early or late pregnancy influences associations with preeclampsia and preterm delivery.

DESIGN

Population based prospective cohort study.

SETTING

Norway, between 1999 and 2008.

PARTICIPANTS

70 149 singleton pregnancies resulting in live-born babies from the Norwegian Mother and Child Cohort Study (no chronic disease, answered questionnaires, no placenta previa/cerclage/serious malformation of fetus, first enrolment pregnancy). Only nulliparous women (n=37 050) were included in the preeclampsia analysis. Both iatrogenic and spontaneous preterm delivery (between gestational weeks 22+0 and 36+6) with spontaneous term controls (between gestational weeks 39+0 and 40+6) were included in the preterm delivery analysis resulting in 34 458 cases.

MAIN OUTCOME MEASURES

Adjusted OR for preeclampsia and preterm delivery according to consumption of probiotic milk at three different time periods (before pregnancy, during early and late pregnancy).

RESULTS

Probiotic milk intake in late pregnancy (but not before or in early pregnancy) was significantly associated with lower preeclampsia risk (adjusted OR: 0.80 (95% CI 0.68 to 0.94) p-value: 0.007). Probiotic intake during early (but not before or during late pregnancy) was significantly associated with lower risk of preterm delivery (adjusted OR: 0.79 (0.64 to 0.97) p-value: 0.03).

CONCLUSIONS

In this observational study, we found an association between timing of probiotic milk consumption during pregnancy and the incidence of the adverse pregnancy outcomes preeclampsia and preterm delivery. If future randomised controlled trials could establish a causal association between probiotics consumption and reduced risk of preeclampsia and preterm delivery, recommending probiotics would be a promising public health measure to reduce these adverse pregnancy outcomes.

Chronic hepatitis B virus infection and preterm labor(birth) in pregnant women-an updated systematic review and meta-analysis

We aimed to explore whether maternal chronic hepatitis B virus (HBV) infection certainly affects preterm labor (birth) in pregnant women. Four databases were systematically searched up to May 31, 2017, without language restriction. Any study was included if it clearly defined exposure to chronic HBV infection, reported risk of preterm labor or birth in pregnant women, and reported relative risks (RRs) or odds ratios (ORs) or provided data for estimation. RRs (or ORs) with 95% confidence intervals were pooled using random-effects models. Statistical heterogeneity was assessed with Cochran's Q statistic and I2 statistic. Twenty-two observational studies involving 6 141 146 pregnant women (three prospective cohort studies, n = 1 116 799; 15 retrospective cohort studies, n = 5 022 513 and four case-control studies, n = 1834) were included. The risk of preterm labor was significantly intensified with chronic HBV infection compared with uninfected women, with substantial heterogeneity. Chronic HBV infection was also significantly associated with a 16% increase in the risk of preterm birth, with substantial heterogeneity. The risk of preterm birth significantly increased by 21% in HBsAg+/HBeAg+ pregnant women compared with uninfected pregnant women. Chronic HBV infection intensifies the risk of preterm labor and birth in pregnant women, but this conclusion should be interpreted with caution given the possibility of residual confounding and be confirmed by well-designed studies in the future.

Preterm prelabor rupture of the membranes: A disease of the fetal membranes

Preterm prelabor rupture of the membranes (pPROM) remains a significant obstetric problem that affects 3-4% of all pregnancies and precedes 40-50% of all preterm births. pPROM arises from complex, multifaceted pathways. In this review, we summarize some old concepts and introduce some novel theories related to pPROM pathophysiology. Specifically, we introduce the concept that pPROM is a disease of the fetal membranes where inflammation-oxidative stress axis plays a major role in producing pathways that can lead to membrane weakening through a variety of processes. In addition, we report microfractures in fetal membranes that are likely sites of tissue remodeling during gestation; however, increase in number and morphometry (width and depth) of these microfractures in pPROM membranes suggests reduced remodeling capacity of membranes. Microfractures can act as channels for amniotic fluid leak, and inflammatory cell and microbial migration. Further studies on senescence activation and microfracture formation and their role in maintaining membrane homeostasis are needed to fill the knowledge gaps in our understanding of pPROM as well as provide better screening (biomarker and imaging based) tools for predicting women at high risk for pPROM and subsequent preterm birth.

Role of NF-κB/GATA3 in the inhibition of lysyl oxidase by IL-1β in human amnion fibroblasts

Preterm premature rupture of membranes (pPROMs) account for one-third of preterm births, a leading cause of neonatal death. Understanding the mechanism of membrane rupture is thus of clinical significance in the prevention of preterm birth. Parturition at both term and preterm is associated with increased abundance of proinflammatory cytokines in the fetal membranes regardless of the presence of infection, which is believed to induce rupture of membranes through activation of the matrix metalloproteinases. It remains unknown whether there are any alternative mechanisms underpinning proinflammatory cytokine-induced rupture of membranes. Here we showed that there were reciprocal increases in interleukin-1β (IL-1β) and decreases in lysyl oxidase (LOX), a collagen crosslinking enzyme, in the human amnion tissue following spontaneous rupture of membrane at term and pPROM. Studies using human amnion tissue explants revealed that IL-1β inhibited the expression of LOX, which can be reproduced in cultured human amnion fibroblasts. Mechanistic study revealed that IL-1β inhibited LOX expression through activation of p38 and Erk1/2 mitogen-activated protein kinase pathways, which resulted in the phosphorylation of the nuclear factor kappa light-chain enhancer of activated B (NF-κB) cell subunit p65 as well as GATA binding protein 3 (GATA3). Subsequently, activated NF-κB interacted with GATA3 at the NF-κB binding site of LOX promoter to inhibit its expression. Conclusively, this study has revealed an alternative mechanism that IL-1β may contribute to the rupture of membranes by attenuating collagen crosslinking through downregulation of LOX expression in amnion fibroblasts.