Uterine overdistention induces preterm labor mediated by inflammation: observations in pregnant women and nonhuman primates

Gasotransmitters in pregnancy: from conception to uterine involution

Gasotransmitters are endogenous small gaseous messengers exemplified by nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S or sulfide). Gasotransmitters are implicated in myriad physiologic functions including many aspects of reproduction. Our objective was to comprehensively review basic mechanisms and functions of gasotransmitters during pregnancy from conception to uterine involution and highlight future research opportunities. We searched PubMed and Web of Science databases using combinations of keywords nitric oxide, carbon monoxide, sulfide, placenta, uterus, labor, and pregnancy. We included English language publications on human and animal studies from any date through August 2018 and retained basic and translational articles with relevant original findings. All gasotransmitters activate cGMP signaling. NO and sulfide also covalently modify target protein cysteines. Protein kinases and ion channels transduce gasotransmitter signals, and co-expressed gasotransmitters can be synergistic or antagonistic depending on cell type. Gasotransmitters influence tubal transit, placentation, cervical remodeling, and myometrial contractility. NO, CO, and sulfide dilate resistance vessels, suppress inflammation, and relax myometrium to promote uterine quiescence and normal placentation. Cervical remodeling and rupture of fetal membranes coincide with enhanced oxidation and altered gasotransmitter metabolism. Mechanisms mediating cellular and organismal changes in pregnancy due to gasotransmitters are largely unknown. Altered gasotransmitter signaling has been reported for preeclampsia, intrauterine growth restriction, premature rupture of membranes, and preterm labor. However, in most cases specific molecular changes are not yet characterized. Nonclassical signaling pathways and the crosstalk among gasotransmitters are emerging investigation topics.

Novel pathways of inflammation in human fetal membranes associated with preterm birth and preterm pre-labor rupture of the membranes

Spontaneous preterm birth (PTB) and preterm pre-labor rupture of the membranes (pPROM) are major pregnancy complications. Although PTB and pPROM have common etiologies, they arise from distinct pathophysiologic pathways. Inflammation is a common underlying mechanism in both conditions. Balanced inflammation is required for fetoplacental growth; however, overwhelming inflammation (physiologic at term and pathologic at preterm) can lead to term and preterm parturition. A lack of effective strategies to control inflammation and reduce the risk of PTB and pPROM suggests that there are several modes of the generation of inflammation which may be dependent on the type of uterine tissue. The avascular fetal membrane (amniochorion), which provides structure, support, and protection to the intrauterine cavity, is one of the key contributors of inflammation. Localized membrane inflammation helps tissue remodeling during pregnancy. Two unique mechanisms that generate balanced inflammation are the progressive development of senescence (aging) and cyclic cellular transitions: epithelial to mesenchymal (EMT) and mesenchymal to epithelial (MET). The intrauterine build-up of oxidative stress at term or in response to risk factors (preterm) can accelerate senescence and promote a terminal state of EMT, resulting in the accumulation of inflammation. Inflammation degrades the matrix and destabilizes membrane function. Inflammatory mediators from damaged membranes are propagated via extracellular vesicles (EV) to maternal uterine tissues and transition quiescent maternal uterine tissues into an active state of labor. Membrane inflammation and its propagation are fetal signals that may promote parturition. This review summarizes the mechanisms of fetal membrane cellular senescence, transitions, and the generation of inflammation that contributes to term and preterm parturitions.

Multiomic immune clockworks of pregnancy

Preterm birth is the leading cause of mortality in children under the age of five worldwide. Despite major efforts, we still lack the ability to accurately predict and effectively prevent preterm birth. While multiple factors contribute to preterm labor, dysregulations of immunological adaptations required for the maintenance of a healthy pregnancy is at its pathophysiological core. Consequently, a precise understanding of these chronologically paced immune adaptations and of the biological pacemakers that synchronize the pregnancy "immune clock" is a critical first step towards identifying deviations that are hallmarks of peterm birth. Here, we will review key elements of the fetal, placental, and maternal pacemakers that program the immune clock of pregnancy. We will then emphasize multiomic studies that enable a more integrated view of pregnancy-related immune adaptations. Such multiomic assessments can strengthen the biological plausibility of immunological findings and increase the power of biological signatures predictive of preterm birth.

Cervical pessary to prevent preterm birth in asymptomatic high-risk women: a systematic review and meta-analysis

BACKGROUND

Randomized controlled trials that have assessed the efficacy of cervical pessary to prevent preterm birth in asymptomatic high-risk women have reported conflicting results.

OBJECTIVE

To evaluate the efficacy and safety of cervical pessary to prevent preterm birth and adverse perinatal outcomes in asymptomatic high-risk women.

DATA SOURCES

MEDLINE, EMBASE, POPLINE, CINAHL, and LILACS (from their inception to October 31, 2019), Cochrane databases, Google Scholar, bibliographies, and conference proceedings.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials that compared cervical pessary with standard care (no pessary) or alternative interventions in asymptomatic women at high risk for preterm birth.

STUDY APPRAISAL AND SYNTHESIS METHODS

The systematic review was conducted according to the Cochrane Handbook guidelines. The primary outcome was spontaneous preterm birth <34 weeks of gestation. Secondary outcomes included adverse pregnancy, maternal, and perinatal outcomes. Pooled relative risks with 95% confidence intervals were calculated. Quality of evidence was assessed using the GRADE methodology.

RESULTS

Twelve studies (4687 women and 7167 fetuses/infants) met the inclusion criteria: 8 evaluated pessary vs no pessary in women with a short cervix, 2 assessed pessary vs no pessary in unselected multiple gestations, and 2 compared pessary vs vaginal progesterone in women with a short cervix. There were no significant differences between the pessary and no pessary groups in the risk of spontaneous preterm birth <34 weeks of gestation among singleton gestations with a cervical length ≤25 mm (relative risk, 0.80; 95% confidence interval, 0.43-1.49; 6 trials, 1982 women; low-quality evidence), unselected twin gestations (relative risk, 1.05; 95% confidence interval, 0.79-1.41; 1 trial, 1177 women; moderate-quality evidence), twin gestations with a cervical length <38 mm (relative risk, 0.75; 95% confidence interval, 0.41-1.36; 3 trials, 1128 women; low-quality evidence), and twin gestations with a cervical length ≤25 mm (relative risk; 0.72, 95% confidence interval, 0.25-2.06; 2 trials, 348 women; low-quality evidence). Overall, no significant differences were observed between the pessary and no pessary groups in preterm birth <37, <32, and <28 weeks of gestation, and most adverse pregnancy, maternal, and perinatal outcomes (low- to moderate-quality evidence for most outcomes). There were no significant differences in the risk of spontaneous preterm birth <34 weeks of gestation between pessary and vaginal progesterone in singleton gestations with a cervical length ≤25 mm (relative risk, 0.99; 95% confidence interval, 0.54-1.83; 1 trial, 246 women; low-quality evidence) and twin gestations with a cervical length <38 mm (relative risk, 0.73; 95% confidence interval, 0.46-1.18; 1 trial, 297 women; very low-quality evidence). Vaginal discharge was significantly more frequent in the pessary group than in the no pessary and vaginal progesterone groups (relative risks, ∼2.20; high-quality evidence).

CONCLUSION

Current evidence does not support the use of cervical pessary to prevent preterm birth or to improve perinatal outcomes in singleton or twin gestations with a short cervix and in unselected twin gestations.

The Role of Danger Associated Molecular Patterns in Human Fetal Membrane Weakening

The idea that cellular stress (including that precipitated by stretch), plays a significant role in the mechanisms initiating parturition, has gained considerable traction over the last decade. One key consequence of this cellular stress is the increased production of Danger Associated Molecular Patterns (DAMPs). This diverse family of molecules are known to initiate inflammation through their interaction with Pattern Recognition Receptors (PRRs) including, Toll-like receptors (TLRs). TLRs are the key innate immune system surveillance receptors that detect Pathogen Associated Molecular Patterns (PAMPs) during bacterial and viral infection. This is also seen during Chorioamnionitis. The activation of TLR commonly results in the activation of the pro-inflammatory transcription factor Nuclear Factor Kappa-B (NF-kB) and the downstream production of pro-inflammatory cytokines. It is thought that in the human fetal membranes both DAMPs and PAMPs are able, perhaps via their interaction with PRRs and the induction of their downstream inflammatory cascades, to lead to both tissue remodeling and weakening. Due to the high incidence of infection-driven Pre-Term Birth (PTB), including those that have preterm Premature Rupture of the Membranes (pPROM), the role of TLR in fetal membranes with Chorioamnionitis has been the subject of considerable study. Most of the work in this field has focused on the effect of PAMPs on whole pieces of fetal membrane and the resultant inflammatory cascade. This is important to understand, in order to develop novel prevention, detection, and therapeutic approaches, which aim to reduce the high number of mothers suffering from infection driven PTB, including those with pPROM. Studying the role of sterile inflammation driven by these endogenous ligands (DAMPs) activating PRRs system in the mesenchymal and epithelial cells in the amnion is important. These cells are key for the maintenance of the integrity and strength of the human fetal membranes. This review aims to (1) summarize the knowledge to date pertinent to the role of DAMPs and PRRs in fetal membrane weakening and (2) discuss the clinical potential brought by a better understanding of these pathways by pathway manipulation strategies.

Mid-trimester amniotic fluid proteome's association with spontaneous preterm delivery and gestational duration

BACKGROUND

Amniotic fluid is clinically accessible via amniocentesis and its protein composition may correspond to birth timing. Early changes in the amniotic fluid proteome could therefore be associated with the subsequent development of spontaneous preterm delivery.

OBJECTIVE

The main objective of this study was to perform unbiased proteomics analysis of the association between mid-trimester amniotic fluid proteome and spontaneous preterm delivery and gestational duration, respectively. A secondary objective was to validate and replicate the findings by enzyme-linked immunosorbent assay using a second independent cohort.

METHODS

Women undergoing a mid-trimester genetic amniocentesis at Sahlgrenska University Hospital/Östra between September 2008 and September 2011 were enrolled in this study, designed in three analytical stages; 1) an unbiased proteomic discovery phase using LC-MS analysis of 22 women with subsequent spontaneous preterm delivery (cases) and 37 women who delivered at term (controls), 2) a validation phase of proteins of interest identified in stage 1, and 3) a replication phase of the proteins that passed validation using a second independent cohort consisting of 20 cases and 40 matched controls.

RESULTS

Nine proteins were nominally significantly associated with both spontaneous preterm delivery and gestational duration, after adjustment for gestational age at sampling, but none of the proteins were significant after correction for multiple testing. Several of these proteins have previously been described as being associated with spontaneous PTD etiology and six of them were thus validated using enzyme linked immunosorbent assay. Two of the proteins passed validation; Neutrophil gelatinase-associated lipocalin and plasminogen activator inhibitor 1, but the results could not be replicated in a second cohort.

CONCLUSIONS

Neutrophil gelatinase-associated lipocalin and Plasminogen activator inhibitor 1 are potential biomarkers of spontaneous preterm delivery and gestational duration but the findings could not be replicated. The negative findings are supported by the fact that none of the nine proteins from the exploratory phase were significant after correction for multiple testing.

A Broad Spectrum Chemokine Inhibitor Prevents Preterm Labor but Not Microbial Invasion of the Amniotic Cavity or Neonatal Morbidity in a Non-human Primate Model

Leukocyte activation within the chorioamniotic membranes is strongly associated with inflammation and preterm labor (PTL). We hypothesized that prophylaxis with a broad-spectrum chemokine inhibitor (BSCI) would downregulate the inflammatory microenvironment induced by Group B Streptococcus (GBS, Streptococcus agalactiae) to suppress PTL and microbial invasion of the amniotic cavity (MIAC). To correlate BSCI administration with PTL and MIAC, we used a unique chronically catheterized non-human primate model of Group B Streptococcus (GBS)-induced PTL. In the early third trimester (128–138 days gestation; ~29–32 weeks human pregnancy), animals received choriodecidual inoculations of either: (1) saline (N = 6), (2) GBS, 1–5 × 10⁸ colony forming units (CFU)/ml; N = 5), or (3) pre-treatment and daily infusions of a BSCI (10 mg/kg intravenous and intra-amniotic) with GBS (1–5 × 10⁸ CFU/ml; N = 4). We measured amniotic cavity pressure (uterine contraction strength) and sampled amniotic fluid (AF) and maternal blood serially and cord blood at delivery. Cesarean section was performed 3 days post-inoculation or earlier for PTL. Data analysis used Fisher's exact test, Wilcoxon rank sum and one-way ANOVA with Bonferroni correction. Saline inoculation did not induce PTL or infectious sequelae. In contrast, GBS inoculation typically induced PTL (4/5, 80%), MIAC and fetal bacteremia (3/5; 60%). Remarkably, PTL did not occur in the BSCI+GBS group (0/4, 0%; p = 0.02 vs. GBS), despite MIAC and fetal bacteremia in all cases (4/4; 100%). Compared to the GBS group, BSCI prophylaxis was associated with significantly lower cytokine levels including lower IL-8 in amniotic fluid (p = 0.03), TNF-α in fetal plasma (p < 0.05), IFN-α and IL-7 in the fetal lung (p = 0.02) and IL-18, IL-2, and IL-7 in the fetal brain (p = 0.03). Neutrophilic chorioamnionitis was common in the BSCI and GBS groups, but was more severe in the BSCI+GBS group with greater myeloperoxidase staining (granulocyte marker) in the amnion and chorion (p < 0.05 vs. GBS). Collectively, these observations indicate that blocking the chemokine response to infection powerfully suppressed uterine contractility, PTL and the cytokine response, but did not prevent MIAC and fetal pneumonia. Development of PTL immunotherapies should occur in tandem with evaluation for AF microbes and consideration for antibiotic therapy.

Twin pregnancies with uterine fibroids are not at increased risk for obstetric complications: single center cohort study

BACKGROUND

Twin pregnancies with uterine fibroid(s) (UFs) may not be at increased risk for obstetric complications compared to those without UFs. However, there was no reported comparison study with obstetric outcomes and complications of twin pregnancy after myomectomy. We aimed to compare the pregnancy outcomes in twin pregnancies with or without uterine fibroid(s), and also compared in patients with previous myomectomy history in Korean women.

METHODS

A cohort of twin pregnancies delivered in a single institution between January 2011 and March 2019 were retrospectively analyzed. UFs group was defined by the presence of UFs during pregnancy (≥1 fibroid, measuring ≥2 cm or multiple fibroids regardless of the size). Previous myomectomy group included patients with history of abdominal or laparoscopic or hysteroscopic myomectomy of ≥1 fibroid, measuring ≥2 cm or multiple fibroids whatever the size. Patients with monochorionic monoamniotic twins, myoma less than 2 cm in size, missed abortion or intrauterine fetal death (IUFD) of one fetus before 14 weeks, history of previous conization, and uterine anomalies were excluded. Pregnancy outcomes and obstetric complications were compared.

RESULT

A total 1388 patients were included in this study, 191 (13.8%) had UFs and 89 (6.4%) had a history of myomectomy. Maternal age was younger in non-UFs group and primiparity was more common in UFs group (p < 0.001, and p = 0.019). No significant differences were found in the gestational age at delivery (p = 0.657), delivery before 37 weeks (p = 0.662), delivery before 34 weeks (p = 0.340), and sum of birth weight of twin (p = 0.307). There were also no statistical differences in rates of obstetrical complications, such as preeclampsia, gestational diabetes mellitus, placenta previa, placenta abruption, cerclage, small for gestational age, IUFD, postpartum hemorrhage and peripartum transfusion or ICU care. These obstetrical outcomes and complications showed no statistical differences between UFs group and previous myomectomy group.

CONCLUSION

In patients with twin pregnancies, the presence of UFs or history of previous myomectomy did not relate to negative effects on pregnancy outcomes and obstetrical complications.

Targeting Toll-like receptor-4 to tackle preterm birth and fetal inflammatory injury

Every year, 15 million pregnancies end prematurely, resulting in more than 1 million infant deaths and long-term health consequences for many children. The physiological processes of labour and birth involve essential roles for immune cells and pro-inflammatory cytokines in gestational tissues. There is compelling evidence that the mechanisms underlying spontaneous preterm birth are initiated when a premature and excessive inflammatory response is triggered by infection or other causes. Exposure to pro-inflammatory mediators is emerging as a major factor in the 'fetal inflammatory response syndrome' that often accompanies preterm birth, where unscheduled effects in fetal tissues interfere with normal development and predispose to neonatal morbidity. Toll-like receptors (TLRs) are critical upstream gatekeepers of inflammatory activation. TLR4 is prominently involved through its ability to sense and integrate signals from a range of microbial and endogenous triggers to provoke and perpetuate inflammation. Preclinical studies have identified TLR4 as an attractive pharmacological target to promote uterine quiescence and protect the fetus from inflammatory injury. Novel small-molecule inhibitors of TLR4 signalling, specifically the non-opioid receptor antagonists (+)-naloxone and (+)-naltrexone, are proving highly effective in animal models for preventing preterm birth induced by bacterial mimetic LPS, heat-killed Escherichia coli, or the TLR4-dependent pro-inflammatory lipid, platelet-activating factor (PAF). Here, we summarise the rationale for targeting TLR4 as a master regulator of inflammation in fetal and gestational tissues, and the potential utility of TLR4 antagonists as candidates for preventative and therapeutic application in preterm delivery and fetal inflammatory injury.

Myometrial activation: Novel concepts underlying labor

Term labour is a state of physiological inflammation orchestrated by multiple uterine tissues (both fetal and maternal). This physiological inflammation preceding and accompanying labour onset is characterized by an increase in cytokine and chemokine secretion by the fetal membranes, as well as uterine tissues (i.e., decidua and myometrium). Pro-inflammatory cytokines and chemokines activate circulating maternal peripheral leukocytes as well as the uterine vascular endothelium to permit leukocyte infiltration into the uterus. This inflammatory milieu, in the absence of infection, is required for the initiation of labour as the uterine-infiltrated leukocytes secrete matrix metalloproteinases to induce fetal membrane rupture and cervical ripening as well as various labour mediators, which promote contractions of the myometrium. Myometrial activation at term and the onset of labour contractions are directly related to the changes in the ovarian/placental hormone progesterone and its downstream mediators (i.e., the progesterone receptors, PRA/B), which are also critical for maintenance of pregnancy. Our recent data provides direct evidence in support of local and functional P4 withdrawal in the uterine muscle (myometrium) via the activator protein-1 (AP-1) mediated pathway. This review outlines known mechanisms regulating activation of human labour, including progesterone and cytokine signaling. Understanding of the molecular mechanism of myometrial activation and labour onset could facilitate the development of new therapeutics for high-risk pregnant women to prevent premature uterine activation and preterm birth.

Comparison of the myometrial transcriptome from singleton and twin pregnancies by RNA-Seq

Preterm birth is recognized as the primary cause of infant mortality worldwide. Twin pregnancies are significantly more at risk of preterm birth than singleton pregnancies. A greater understanding of why this is and better modes of treatment and prevention are needed. Key to this is determining the differing pathophysiological mechanisms of preterm birth in twins, including the role of the myometrium and premature uterine contraction. We performed RNA sequencing (RNA-Seq) of human myometrium from singleton and twin pregnancies at term (> 37+0 weeks) and preterm (< 37+0 weeks), collected during pre-labour Caesarean Section. RNA-Seq libraries were prepared from polyA-selected RNA and sequenced on the Illumina HiSeq 4000 platform. Differentially expressed genes (DEGs), GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment were conducted using R software. Significance was determined with a false discovery rate-adjusted P value of <0.05. Only 3 DEGs were identified between gestational age-matched singleton and twin myometrium and only 1 DEG identified between singleton term and twin preterm tissues. Comparison of singleton preterm myometrium with twin term myometrium however, revealed 75 down-regulated and 24 up-regulated genes in twin myometrium. This included genes associated with inflammation and immune response, T cell maturation and differentiation and steroid biosynthesis. GO and KEGG enrichment analyses for biologically relevant processes and functions also revealed several terms related to inflammation and immune response, as well as cytokine-cytokine receptor interaction and chemokine receptor signalling. Data indicate that little or no differences exist in the transcriptome of singleton and twin myometrium when matched for gestational age. The significant up- and down-regulation of genes identified between preterm singleton and twin myometrium at term may point to transcriptome changes associated with the chronic levels of uterine stretch in twin pregnancy or genes associated with the myometrium transitioning to labour onset.

Effect of intra-amniotic fluid pressure from polyhydramnios on cervical length in patients with twin-twin transfusion syndrome undergoing fetoscopic laser surgery

OBJECTIVES

To determine the relationship between intra-amniotic pressure and cervical length (CL) in patients with twin-twin transfusion syndrome (TTTS) undergoing fetoscopic laser photocoagulation (FLP), and to identify pre- or intraoperative factors associated with increased intra-amniotic pressure in this population.

METHODS

This was a prospective cohort study of patients undergoing FLP for TTTS. Exclusion criteria were triplet or higher-order gestation and prior cervical cerclage, amnioreduction or FLP procedure. CL was assessed using preprocedure transvaginal ultrasound. Intra-amniotic pressure measurements were obtained on initial placement of the trocar into the amniotic cavity, using a direct hydrostatic pressure gauge. The relationship between intra-amniotic pressure and CL was assessed using multivariate linear regression analysis, including relevant preoperative and intraoperative variables.

RESULTS

In total, 283 pregnancies met the inclusion criteria. Quintero stage of TTTS was I in 33 pregnancies, II in 88, III in 150 and IV in 12. Mean gestational age (GA) at FLP was 20.7 ± 3 weeks. Mean intra-amniotic pressure was 23.1 ± 9 mmHg. On unadjusted linear regression analysis, there was no significant association between intra-amniotic pressure and preoperative CL (P = 0.24) or GA at delivery (P = 0.22). On multivariate analysis, the factors associated significantly with intra-amniotic pressure were: number of prior term deliveries (P = 0.03), recipient maximum vertical pocket (P < 0.0001), Quintero stage IV (P = 0.01) and type of anesthesia (sedation vs general anesthesia; P = 0.01).

CONCLUSION

In pregnancies with TTTS, intra-amniotic pressure is not associated with CL or GA at delivery. This novel finding suggests that cervical shortening in this population is not mechanically driven. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Antibiotic administration can eradicate intra-amniotic infection or intra-amniotic inflammation in a subset of patients with preterm labor and intact membranes

BACKGROUND

Intra-amniotic infection is present in 10% of patients with an episode of preterm labor, and is a risk factor for impending preterm delivery and neonatal morbidity/mortality. Intra-amniotic inflammation is often associated with intra-amniotic infection, but is sometimes present in the absence of detectable microorganisms. Antibiotic treatment of intra-amniotic infection has traditionally been considered to be ineffective. Intra-amniotic inflammation without microorganisms has a prognosis similar to that of intra-amniotic infection.

OBJECTIVE

To determine whether antibiotics can eradicate intra-amniotic infection or intra-amniotic inflammation in a subset of patients with preterm labor and intact membranes.

MATERIALS AND METHODS

The study population consisted of women who met the following criteria: 1) singleton gestation between 20 and 34 weeks; 2) preterm labor and intact membranes; 3) transabdominal amniocentesis performed for the evaluation of the microbiologic/inflammatory status of the amniotic cavity; 4) intra-amniotic infection and/or intra-amniotic inflammation; and 5) received antibiotic treatment that consisted of ceftriaxone, clarithromycin, and metronidazole. Follow-up amniocentesis was performed in a subset of patients. Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and polymerase chain reaction was performed for Ureaplasma spp. Intra-amniotic infection was defined as a positive amniotic fluid culture or positive polymerase chain reaction, and intra-amniotic inflammation was suspected when there was an elevated amniotic fluid white blood cell count or a positive result of a rapid test for matrix metalloproteinase-8. For this study, the final diagnosis of intra-amniotic inflammation was made by measuring the interleukin-6 concentration in stored amniotic fluid (>2.6 ng/mL). These results were not available to managing clinicians. Treatment success was defined as eradication of intra-amniotic infection and/or intra-amniotic inflammation or delivery ≥37 weeks.

RESULTS

Of 62 patients with intra-amniotic infection and/or intra-amniotic inflammation, 50 received the antibiotic regimen. Of those patients, 29 were undelivered for ≥7 days and 19 underwent a follow-up amniocentesis. Microorganisms were identified by culture or polymerase chain reaction of amniotic fluid obtained at admission in 21% of patients (4/19) who had a follow-up amniocentesis, and were eradicated in 3 of the 4 patients. Resolution of intra-amniotic infection/inflammation was confirmed in 79% of patients (15/19), and 1 other patient delivered at term, although resolution of intra-amniotic inflammation could not be confirmed after a follow-up amniocentesis. Thus, resolution of intra-amniotic inflammation/infection or term delivery (treatment success) occurred in 84% of patients (16/19) who had a follow-up amniocentesis. Treatment success occurred in 32% of patients (16/50) with intra-amniotic infection/inflammation who received antibiotics. The median amniocentesis-to-delivery interval was significantly longer among women who received the combination of antibiotics than among those who did not (11.4 days vs 3.1 days: P = .04).

CONCLUSION

Eradication of intra-amniotic infection/inflammation after treatment with antibiotics was confirmed in 79% of patients with preterm labor, intact membranes, and intra-amniotic infection/inflammation who had a follow-up amniocentesis. Treatment success occurred in 84% of patients who underwent a follow-up amniocentesis and in 32% of women who received the antibiotic regimen.

Large-for-gestational-age fetuses have an increased risk for spontaneous preterm birth

OBJECTIVE

Our aim was to investigate the association between large-for-gestational-age and the risk of spontaneous preterm birth.

STUDY DESIGN

We studied nulliparous women with a singleton gestation using data from the Dutch perinatal registry from 1999 to 2010. Neonates were categorized according to the Hadlock fetal weight standard, into 10th to 90th percentile, 90th to 97th percentile, or above 97th percentile. Outcomes were preterm birth <37⁺⁰ weeks and preterm birth between 25⁺⁰-27⁺⁶ weeks, 28⁺⁰-30⁺⁶ weeks, 31⁺⁰-33⁺⁶ weeks, and 34⁺⁰-36⁺⁶ weeks.

RESULTS

We included 547,418 women. The number of spontaneous preterm births <37 weeks was significantly increased in the large-for-gestational-age group ( > p97) compared with fetuses with a normal growth (p10-p90) (11.3% vs. 7.3%, odds ratio (OR) 1.8; 95% CI 1.7-1.9). The same results were found when limiting analyses to women with certain pregnancy duration (after in vitro fertilization).

CONCLUSION

Large-for-gestational-age increases the risk of spontaneous preterm delivery from 25 weeks of gestation onwards.

Initiation of human parturition: signaling from senescent fetal tissues via extracellular vesicle mediated paracrine mechanism

A better understanding of the underlying mechanisms by which signals from the fetus initiate human parturition is required. Our recent findings support the core hypothesis that oxidative stress (OS) and cellular senescence of the fetal membranes (amnion and chorion) trigger human parturition. Fetal membrane cell senescence at term is a natural physiological response to OS that occurs as a result of increased metabolic demands by the maturing fetus. Fetal membrane senescence is affected by the activation of the p38 mitogen activated kinase-mediated pathway. Similarly, various risk factors of preterm labor and premature rupture of the membranes also cause OS-induced senescence. Data suggest that fetal cell senescence causes inflammatory senescence-associated secretory phenotype (SASP) release. Besides SASP, high mobility group box 1 and cell-free fetal telomere fragments translocate from the nucleus to the cytosol in senescent cells, where they represent damage-associated molecular pattern markers (DAMPs). In fetal membranes, both SASPs and DAMPs augment fetal cell senescence and an associated ‘sterile’ inflammatory reaction. In senescent cells, DAMPs are encapsulated in extracellular vesicles, specifically exosomes, which are 30–150 nm particles, and propagated to distant sites. Exosomes traffic from the fetus to the maternal side and cause labor-associated inflammatory changes in maternal uterine tissues. Thus, fetal membrane senescence and the inflammation generated from this process functions as a paracrine signaling system during parturition. A better understanding of the premature activation of these signals can provide insights into the mechanisms by which fetal signals initiate preterm parturition.

Quantitative Ultrasound Parameters Based on the Backscattered Echo Power Signal as Biomarkers of Cervical Remodeling: A Longitudinal Study in the Pregnant Rhesus Macaque

Clinical prediction and especially prevention of abnormal birth timing, particularly pre-term, is poor. The cervix plays a key role in birth timing; it first serves as a rigid barrier to protect the developing fetus, then becomes the pathway to delivery of that fetus. Imaging biomarkers to define this remodeling process could provide insights to improve prediction of birth timing and elucidate novel targets for preventive therapies. Quantitative ultrasound (QUS) approaches that appear promising for this purpose include shear wave speed (SWS) estimation to quantify softness, as well as parameters based on backscattered power, such as the mean backscattered power difference (mBSPD) and specific attenuation coefficient (SAC), to quantify the organization of tissue microstructure. Invasive studies in rodents demonstrated that as pregnancy advances, cervical microstructure disorganizes as tissue softness and compliance increase. Our non-invasive studies in pregnant women and rhesus macaques suggested that QUS can detect these microstructural changes in vivo. Our previous study in the same cohort showed a progressive decline in SWS during pregnancy, consistent with increasing tissue softness, and we hypothesized that backscatter parameters would also decrease, consistent with increasing microstructural disorganization. In this study, we analyzed the mBSPD and SAC in the cervices of rhesus macaques (n = 18). We found that both mBSPD and SAC decreased throughout pregnancy (p < 0.001 for both parameters) and that the former appears to be a more reliable biomarker. In summary, biomarkers that can characterize tissue microstructural organization are promising for comprehensive characterization of cervical remodeling in pregnancy.

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.

Targeting mechanotransduction mechanisms and tissue weakening signals in the human amniotic membrane

Mechanical and inflammatory signals in the fetal membrane play an important role in extracellular matrix (ECM) remodelling in order to dictate the timing of birth. We developed a mechanical model that mimics repetitive stretching of the amniotic membrane (AM) isolated from regions over the placenta (PAM) or cervix (CAM) and examined the effect of cyclic tensile strain (CTS) on mediators involved in mechanotransduction (Cx43, AKT), tissue remodelling (GAGs, elastin, collagen) and inflammation (PGE₂, MMPs). In CAM and PAM specimens, the application of CTS increased GAG synthesis, PGE₂ release and MMP activity, with concomitant reduction in collagen and elastin content. Co-stimulation with CTS and pharmacological agents that inhibit either Cx43 or AKT, differentially influenced collagen, GAG and elastin in a tissue-dependent manner. SHG confocal imaging of collagen fibres revealed a reduction in SHG intensity after CTS, with regions of disorganisation dependent on tissue location. CTS increased Cx43 and AKT protein and gene expression and the response could be reversed with either CTS, the Cx43 antisense or AKT inhibitor. We demonstrate that targeting Cx43 and AKT prevents strain-induced ECM damage and promotes tissue remodelling mechanisms in the AM. We speculate that a combination of inflammatory and mechanical factors could perturb typical mechanotransduction processes mediated by Cx43 signalling. Cx43 could therefore be a potential therapeutic target to prevent inflammation and preterm premature rupture of the fetal membranes.

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.

The role of maternal T cell and macrophage activation in preterm birth: Cause or consequence?

The role of the immune system in term (TL) and preterm labor (PTL) is unknown. Despite the fact that globally, PTL remains the most important cause of childhood mortality. Infection, typically of the fetal membranes, termed chorioamnionitis, is the best-understood driver of PTL, but the mechanisms underpinning other causes, including idiopathic and stretch-induced PTL, are unclear, but may well involve activation of the maternal immune system. The final common pathway of placental dysfunction, fetal membrane rupture, cervical dilation and uterine contractions are highly complex processes. At term, choriodecidual rather than myometrial inflammation is thought to drive the onset of labor and similar findings are present in different types of PTL including idiopathic PTL. Although accumulated data has confirmed an association between the immune response and preterm birth, there is yet a need to understand if this response is an initiator or a consequence of tissue-level dysregulation. This review focuses on the potential role of macrophages and T cells in innate and adaptive immunity relevant to preterm birth in humans and animal models.

Spontaneous premature birth as a target of genomic research

Spontaneous preterm birth is a serious and common pregnancy complication associated with hormonal dysregulation, infection, inflammation, immunity, rupture of fetal membranes, stress, bleeding, and uterine distention. Heredity is 25-40% and mostly involves the maternal genome, with contribution of the fetal genome. Significant discoveries of candidate genes by genome-wide studies and confirmation in independent replicate populations serve as signposts for further research. The main task is to define the candidate genes, their roles, localization, regulation, and the associated pathways that influence the onset of human labor. Genomic research has identified some candidate genes that involve growth, differentiation, endocrine function, immunity, and other defense functions. For example, selenocysteine-specific elongation factor (EEFSEC) influences synthesis of selenoproteins. WNT4 regulates decidualization, while a heat-shock protein family A (HSP70) member 1 like, HSPAIL, influences expression of glucocorticoid receptor and WNT4. Programming of pregnancy duration starts before pregnancy and during placentation. Future goals are to understand the interactive regulation of the pathways in order to define the clocks that influence the risk of prematurity and the duration of pregnancy. Premature birth has a great impact on the duration and the quality of life. Intensification of focused research on causes, prediction and prevention of prematurity is justified.

Risk of singleton preterm birth after prior twin preterm birth: a cohort study

Objective: To determine whether preterm birth in a twin pregnancy increases the risk of subsequent preterm birth (PTB) in a singleton pregnancy and to identify predictors for singleton PTB in women with previous twin PTB.Method: A retrospective cohort study of women with prior twin birth followed by a singleton birth in two tertiary referral centres between 2000 and 2016 was conducted. Rate of PTB in subsequent singleton pregnancy was compared between women who experienced previous preterm versus term twin birth. Analysis was further stratified by gestational age at twin and singleton birth, etiology for PTB and chorionicity in the twin pregnancy.Results: A total of 378 women met the inclusion criteria, of whom 252 (66.7%) experienced PTB in the index twin pregnancy. The overall rate of PTB in the subsequent singleton pregnancy was 11.6% (44/378). Women with prior twin PTB had a higher rate of PTB in the subsequent singleton pregnancy compared with women with prior term twin birth (17.5 versus 6.3%, p = .003, or 3.12, 95%-CI 1.42-6.85), mainly due to a higher rate of late singleton preterm birth (13.1 versus 4.0%, p = .005). Findings of higher odds of PTB in the subsequent singleton pregnancy was limited to women who gave birth before 34^0/7 weeks in the twin pregnancy and was related to the degree of prematurity (prior twin PTB at 30^0/7-33^6/7weeks: OR 3.09, 95%-CI 1.12-8.51; prior twin PTB at <30^0/7weeks: OR 5.8, 95%-CI 2.46-13.68). The association between previous twin PTB and subsequent singleton PTB was limited to women with prior spontaneous twin PTB (OR 3.34, 95%-CI 1.50-7.45).Conclusion: Women with a history of spontaneous PTB in a twin pregnancy are at increased odds of PTB in subsequent singleton pregnancies compared to women with prior term twin birth, and the risk is related to the severity of prematurity in the index twin pregnancy.

The frequency and clinical significance of intra-amniotic inflammation in twin pregnancies with preterm labor and intact membranes

OBJECTIVE

The objective of this study is to evaluate the frequency and clinical significance of intra-amniotic inflammation in twin pregnancies with preterm labor and intact membranes.

STUDY DESIGN

Amniotic fluid (AF) was retrieved from both sacs in 90 twin gestations with preterm labor and intact membranes (gestational age between 20 and 34 6/7 weeks). Preterm labor was defined as the presence of painful regular uterine contractions, with a frequency of at least 2 every 10 min, requiring hospitalization. Fluid was cultured and assayed for matrix metalloproteinase-8. Intra-amniotic inflammation was defined as an AF matrix metalloproteinase-8 concentration >23 ng/mL.

RESULTS

The prevalence of intra-amniotic inflammation for at least 1 amniotic sac was 39% (35/90), while that of proven intra-amniotic infection for at least one amniotic sac was 10% (9/90). Intra-amniotic inflammation without proven microbial invasion of the amniotic cavity was found in 29% (26/90) of the cases. Intra-amniotic inflammation was present in both amniotic sacs for 22 cases, in the presenting amniotic sac for 12 cases, and in the non-presenting amniotic sac for one case. Women with intra-amniotic inflammation observed in at least one amniotic sac and a negative AF culture for microorganisms had a significantly higher rate of adverse pregnancy outcome than those with a negative AF culture and without intra-amniotic inflammation (lower gestational age at birth, shorter amniocentesis-to-delivery interval, and significant neonatal morbidity). Importantly, there was no significant difference in pregnancy outcome between women with intra-amniotic inflammation and a negative AF culture and those with a positive AF culture.

CONCLUSION

Intra-amniotic inflammation is present in 39% of twin pregnancies with preterm labor and intact membranes and is a risk factor for impending preterm delivery and adverse outcome, regardless of the presence or absence of bacteria detected using cultivation techniques.

Diagnostic value of urinary RBP, ALB and AQP2 in neonatal hydronephrosis and the relationship with expression of MCP-1 in the prenatal maternal peripheral blood

Diagnostic value of urinary retinol binding protein (RBP), albumin (ALB) and aquaporin-2 (AQP2) in neonatal hydronephrosis and their relationship with the expression of monocyte chemoattractant protein 1 (MCP-1) in the prenatal maternal peripheral blood was investigated. Forty-six child patients with hydronephrosis admitted to Hongqi Hospital Affiliated to Mudanjiang Medical College from December 2016 to November 2017 were selected as the observation group and the control included 46 normal newborn infants. The urinary RBP, ALB, AQP2 and the expression of MCP-1 in the prenatal maternal peripheral blood in the two groups were compared. The diagnostic value of the combination of urinary RBP, ALB and AQP2 for the neonatal hydronephrosis was accessed through the area under curve (AUC). The changes of urinary RBP, ALB and AQP2 of child patients were observed and the correlations between RBP, ALB, AQP2 and MCP-1 were analyzed. The concentrations of RBP and ALB in the observation group were obviously increased compared to those in the control group. The AQP2 concentration in the observation group was lower than that in the control group. In the observation group, the MCP-1 level in the prenatal maternal blood was significantly higher than that in the control group (P<0.05). After treatment, the concentration of RBP and ALB in the child patients were significantly decreased and AQP2 concentration was increased compared with that before treatment (P<0.05). The AUC of the diagnosis combining with RBP, ALB and AQP2 was 0.913. RBP and ALB were positively correlated to MCP-1 in the prenatal maternal peripheral blood and there was a negative correlation between AQP2 and MCP-1 (P<0.05). In conclusion, urinary RBP, ALB and AQP2 can be regarded as markers for the diagnosis of the neonatal hydronephrosis and they are also closely related to the MCP-1 level in the prenatal maternal peripheral blood.

Multifactorial Regulation of Myometrial Contractility During Pregnancy and Parturition

The steroid hormones progesterone (P₄) and estradiol-17β (E₂), produced by the placenta in humans and the ovaries in rodents, serve crucial roles in the maintenance of pregnancy, and the initiation of parturition. Because of their critical importance for species survival, the mechanisms whereby P₄ and its nuclear receptor (PR) maintain myometrial quiescence during pregnancy, and for the decline in P₄/PR and increase in E₂/estrogen receptor (ER) function leading to parturition, are multifaceted, cooperative, and redundant. These actions of P₄/PR include: (1) PR interaction with proinflammatory transcription factors, nuclear factor κB (NF-κB), and activating protein 1 (AP-1) bound to promoters of proinflammatory and contractile/contraction-associated protein (CAP) genes and recruitment of corepressors to inhibit NF-κB and AP-1 activation of gene expression; (2) upregulation of inhibitors of proinflammatory transcription factor activation (IκBα, MKP-1); (3) induction of transcriptional repressors of CAP genes (e.g., ZEB1). In rodents and most other mammals, circulating maternal P₄ levels remain elevated throughout most of pregnancy and decline precipitously near term. By contrast, in humans, circulating P₄ levels and myometrial PR levels remain elevated throughout pregnancy and into labor. However, even in rodents, wherein P₄ levels decline near term, P₄ levels remain higher than the K_d for PR binding. Thus, parturition is initiated in all species by a series of molecular events that antagonize the P₄/PR maintenance of uterine quiescence. These events include: direct interaction of inflammatory transcription factors (e.g., NF-κB, AP-1) with PR; increased expression of P₄ metabolizing enzymes; increased expression of truncated/inhibitory PR isoforms; altered expression of PR coactivators and corepressors. This article will review various mechanisms whereby P₄ acting through PR isoforms maintains myometrial quiescence during pregnancy as well as those that underlie the decline in PR function leading to labor. The roles of P₄- and E₂-regulated miRNAs in the regulation and integration of these mechanisms will also be considered.

Cell-Free DNA Release by Mouse Fetal Membranes

INTRODUCTION

Cell-free "fetal" DNA is released from the placenta. Because the fetal membranes also arise from the trophectoderm layer of the blastocyst, these studies sought to test the hypothesis that the membranes also release cell-free DNA (cfDNA).

METHODS

Fetal membranes were harvested from pregnant CD-1 mice and cultured in 12-well plates containing media alone or with staurosporine and thapsigargin (apoptosis stimulators), Q-VD-OPh (caspase inhibitor), Trolox (vitamin E analog), and lipopolysaccharide and tumor necrosis factor α (TNFα; inflammatory mediators). The cfDNA in the media was extracted, quantified, and normalized for tissue weight. Media was used for a lactate dehydrogenase (LDH) assay. Membrane homogenates were used to assess activated caspase levels and the expression of DNA fragmentation factor B (DFFB) and BAX proteins. 5-Methylcytosine was assessed using a 5-mC DNA enzyme-linked immunosorbent assay. The cfDNA was used to stimulate interleukin 6 (IL6) release by J774A.1 mouse macrophage cells.

RESULTS

Increased cfDNA release at 6 and 21 hours occurred in parallel with increasing LDH levels. The cfDNA concentrations were significantly suppressed by Q-VD-OPh and Trolox and increased by thapsigargin and TNFα. Increased caspase activity was suppressed by Q-VD-OPh and increased by TNFα, thapsigargin, and staurosporine. The expression of BAX and DFFB proteins significantly increased by 21 hours. 5-Methylcytosine levels were significantly lower in fetal membranes and placentas and below detectable in the cfDNA released by the explants. The cfDNA-stimulated IL6 release by macrophage cells was suppressed by chloroquine, a Toll-like receptor 9 (TLR9) inhibitor.

CONCLUSIONS

These studies have confirmed cfDNA release by the mouse fetal membranes; cfDNA was markedly hypomethylated and a robust stimulator of TLR9.

Uterine distention as a factor in birth timing: retrospective nationwide cohort study in Sweden

OBJECTIVES

To determine whether uterine distention is associated with human pregnancy duration in a non-invasive observational setting.

DESIGN

Retrospective cohort study modelling uterine distention by interaction between maternal height and uterine load.

SETTING

The study is based on the 1990-2013 population data from all delivery units in Sweden.

PARTICIPANTS

Uncomplicated first pregnancies of healthy Nordic-born mothers with spontaneous onset of labour. Pregnancies were classified as twin (n=2846) or singleton (n=527 868). Singleton pregnancies were further classified as carrying a large for gestational age fetus (LGA, n=24 286) or small for gestational age fetus (SGA, n=33 780).

OUTCOME MEASURES

Statistical interaction between maternal height and uterine load categories (twin vs singleton pregnancies, and LGA vs SGA singleton pregnancies), where the outcome is pregnancy duration.

RESULTS

In all models, statistically significant interaction was found. Mothers carrying twins had 2.9 times larger positive linear effect of maternal height on gestational age than mothers carrying singletons (interaction p=5e-14). Similarly, the effect of maternal height was strongly modulated by the fetal growth rate in singleton pregnancies: the effect size of maternal height on gestational age in LGA pregnancies was 2.1 times larger than that in SGA pregnancies (interaction p<1e-11). Preterm birth OR was 1.4 when the mother was short, and 2.8 when the fetus was extremely large for its gestational age; however, when both risk factors were present together, the OR for preterm birth was larger than expected, 10.2 (interaction p<0.0005).

CONCLUSIONS

Across all classes, maternal height was significantly associated with child's gestational age at birth. Interestingly, in short-statured women with large uterine load (twins, LGA), spontaneous delivery occurred much earlier than expected. The interaction between maternal height, uterine load size and gestational age at birth strongly suggests the effect of uterine distention imposed by fetal growth on birth timing.

Leiomyomatous uterus and preterm birth: an exposed/unexposed monocentric cohort study

BACKGROUND

The risk of preterm birth may increase in the presence of uterine leiomyomas during pregnancy. Whether myomectomy abrogates this risk has never been studied.

OBJECTIVE

Our aim was to evaluate the association between the presence of uterine leiomyomas during pregnancy and preterm birth and, if an association exists, to evaluate its persistence in case of a history of myomectomy.

STUDY DESIGN

This exposed/unexposed monocentric retrospective cohort study included all women with singleton pregnancies delivering >22 weeks in a tertiary university hospital maternity unit from January 2011 through September 2015. Women with a leiomyomatous uterus were compared to women with no myomas. Women in the leiomyomatous uterus group were women with uterine leiomyoma(s) during pregnancy (≥1 leiomyoma, measuring ≥20 mm or multiple leiomyomas whatever the size) seen on at least 1 obstetric ultrasound without history of myomectomy, or women with a history of myomectomy (removal of ≥1 leiomyoma, measuring ≥20 mm or multiple leiomyomas whatever the size) by hysteroscopy, laparoscopy, or laparotomy with or without persistent leiomyomas. The association between leiomyomatous uterus and preterm birth was assessed through univariate and multivariable logistic regression.

RESULTS

Among the 19,866 women in the cohort, 301 (1.5%) had a leiomyomatous uterus (154 unoperated women and 147 operated women). The rate of premature delivery was 12.0% in the leiomyomatous uterus group and 8.4% in the nonleiomyomatous uterus group. After adjusting for the risk factors for preterm birth, leiomyomatous uterus was significantly associated with preterm birth (adjusted odds ratio, 2.5; 95% confidence interval, 1.7-3.7). This association was significant for unoperated women (adjusted odds ratio, 2.7; 95% confidence interval, 1.6-4.6) as well as operated women (adjusted odds ratio, 2.3; 95% confidence interval, 1.3-3.9) when compared to the nonleiomyomatous uterus group.

CONCLUSION

Uterine leiomyomas are associated with preterm birth and this association persists after myomectomy.

Impact of maternal pulmonary insufficiency on fetal growth in pregnancy

Rationale: It is known that fetal growth is usually proportional to left-sided cardiac output (CO), which parallels the right-sided CO and that congenital right-sided lesions are usually associated with better perinatal outcomes than left-sided lesions.Objective: Our objective was to document whether newborns from mothers with severe residual pulmonary valve insufficiency (PI) after surgical tetralogy of Fallot (TOF) or pulmonary valve stenosis (PS) correction have lower birth weight (BW) than newborns from mothers with absent, mild, or moderate PI.Methods: This is a retrospective cohort study of women affected with repaired TOF and corrected PS with varied severity of residual PI. Exclusion criteria were: left ventricular dysfunction, left-sided valvular heart disease, other right-sided structural heart disease, chronic hypertension, substance addiction, and incomplete follow-up. Pregnancies were divided into three groups: absent or mild PI, moderate PI, and severe PI. A generalized linear model with normal dependent variable distribution was built and the parameter estimation made with Generalized Estimation Equations (GEE) to take into account repeated mother in data. Variables such as gestational age at birth, maternal age, smoking, and body mass index were tested with bivariate analyses to assess their effect on BW. Only gestational age remained in the adjusted model.Results: A total of 45 patients were included (33 TOF and 12 PS) and 97 pregnancies were reported: 22 miscarriages (22.7%) (15 TOF, 7 PS) and 75 successful pregnancies (57 TOF, 18 PS). The patients were divided into three groups: 1) absent or mild PI, 2) moderate PI, and 3) severe PI groups, which comprised, respectively, 29 (15 TOF, 4 PS), 20 (10 TOF, 1 PS), and 26 successful pregnancies (8 TOF, 7 PS). Using three levels of PI (absent or mild, moderate, and severe), the unadjusted model showed a significant effect of level of PI on BW (p = .0118), as well as the adjusted model (p = .0263) with gestational age as a covariate. The estimated mean newborn's BW was 3055.8 g in the severe PI group, 3151.0 g in the moderate PI group, and 3376.4 g in the absent or mild group when adjusted for gestational age. Hence, we estimated that the mean newborn's BW is 321 g lower in the severe PI group compared with absent or mild PI group ((CI: 572.3; -68.9), p = .0087).Conclusions: Pregnancy is usually well tolerated in repaired TOF and corrected PS. Severe PI either from repaired TOF or PS is at higher risk of lower newborn's BW. Special attention must be paid to the severity of PI. Fetal growth surveillance in the third trimester is warranted.

Preconditioning the uterine unfolded protein response maintains non-apoptotic Caspase 3-dependent quiescence during pregnancy

The prevention of apoptotic caspase 3 activation through biological preconditioning, mediated through the modulation of the unfolded protein response has been demonstrated to ameliorate multiple pathophysiologies. The maintenance of non-apoptotic caspase 3 activity by the unfolded protein response within the pregnant uterus has previously been proven to be critical in inhibiting uterine myocyte contractility during pregnancy. Here we report that the pregnant uterus utilizes an unfolded protein response-preconditioning paradigm to conserve myometrial caspase 3 in a non-apoptotic state in order to effectively inhibit uterine contractility thereby preventing the onset of preterm labor. In the absence of appropriate endogenous preconditioning during pregnancy, uterine caspase 3 is transformed from a non-apoptotic to an apoptotic phenotype. Apoptotic caspase 3 activation results in the precocious triggering of local uterine inflammatory signaling and prostaglandin production, consequently resulting in an increased incidence of preterm birth. These findings represent a paradigm shift in our understanding of how preconditioning promotes the maintenance of uterine non-apoptotic caspase 3 action during pregnancy preventing the onset of premature uterine contraction and therefore defining the timing of the onset of labor.

Understanding fetal factors that contribute to preterm birth: Sjögren-Larsson syndrome as a model

AIM

Preterm birth is the world's leading cause of neonatal death. Unfortunately, the pathophysiology of preterm birth remains poorly understood. Sjögren-Larsson syndrome is a rare, neurometabolic disorder caused by a fatty aldehyde dehydrogenase deficiency. A majority of patients with Sjögren-Larsson syndrome is born preterm.

METHODS

Data of all known Dutch patients with Sjögren-Larsson syndrome and all cases reported in literature were analyzed to learn from preterm birth in context of this rare disease.

RESULTS

Exact gestational age was known in 33 Dutch patients; 24 (73%) of them were born preterm, with a median gestational age of 36 weeks. The literature search confirmed our findings: 13 (59%) of 22 cases was born preterm.

CONCLUSIONS

Preterm birth is a hallmark of Sjögren-Larsson syndrome, presumably caused by the abnormal lipid metabolism of the fetus. At least five additional rare genetic disorders (namely Ehlers-Danlos syndrome, ichthyosis prematurity syndrome, congenital analbuminemia, osteogenesis imperfecta type II and restrictive dermopathy) were found in literature that lead to preterm birth of the affected fetus. These disorders are in fact "experiments of nature" and as such they shed new lights on the mechanisms causing preterm birth.

The uterine pacemaker of labor

The laboring uterus is generally thought to initiate contractions much similar to the heart, with a single, dedicated pacemaker. Research on human and animal models over decades has failed to identify such pacemaker. On the contrary, data indicate that instead of being fixed at a site similar to the sinoatrial node of the heart, the initiation site for each uterine contraction changes during time, often with each contraction. The enigmatic uterine "pacemaker" does not seem to fit the standard definition of what a pacemaker should be. The uterine pacemaker must also mesh with the primary physiological function of the uterus - to generate intrauterine pressure. This requires that most areas of the uterine wall contract in a coordinated, or synchronized, manner for each contraction of labor. It is not clear whether the primary mechanism of the uterine pacemaker is a slow-wave generator or an impulse generator. Slow waves in the gut initiate localized smooth muscle contractions. Because the uterus and the gut have somewhat similar cellular and tissue structure, it is reasonable to consider if uterine contractions are paced by a similar mechanism. Unfortunately, there is no convincing experimental verification of uterine slow waves. Similarly, there is no convincing evidence of a cellular mechanism for impulse generation. The uterus appears to have multiple widely dispersed mechanically sensitive functional pacemakers. It is possible that the coordination of organ-level function occurs through intrauterine pressure, thus creating wall stress followed by activation of many mechanosensitive electrogenic pacemakers.

Quantitative assessment of cervical softening during pregnancy in the Rhesus macaque with shear wave elasticity imaging

Abnormal parturition, e.g. pre- or post-term birth, is associated with maternal and neonatal morbidity and increased economic burden. This could potentially be prevented by accurate detection of abnormal softening of the uterine cervix. Shear wave elasticity imaging (SWEI) techniques that quantify tissue softness, such as shear wave speed (SWS) measurement, are promising for evaluation of the cervix. Still, interpretation of results can be complicated by biological variability (i.e. spatial variations of cervix stiffness, parity), as well as by experimental factors (i.e. type of transducer, posture during scanning). Here we investigated the ability of SWEI to detect cervical softening, as well as sources of SWS variability that can affect this task, in the pregnant and nonpregnant Rhesus macaque. Specifically, we evaluated SWS differences when imaging the cervix transabdominally with a typical linear array abdominal transducer, and transrectally with a prototype intracavitary linear array transducer. Linear mixed effects (LME) models were used to model SWS as a function of menstrual cycle day (in nonpregnant animals) and gestational age (in pregnant animals). Other variables included parity, shear wave direction, and cervix side (anterior versus posterior). In the nonpregnant cervix, the LME model indicated that SWS increased by 2% (95% confidence interval 0-3%) per day, starting eight days before menstruation. During pregnancy, SWS significantly decreased at a rate of 6% (95% CI 5-7%) per week (intracavitary approach) and 3% (95% CI 2-4%) per week (transabdominal approach), and interactions between the scanning approach and other fixed effects were also significant. These results suggest that, while absolute SWS values are influenced by factors such as scanning approach and SWEI implementation, these sources of variability do not compromise the sensitivity of SWEI to cervical softening. Our results also highlight the importance of standardizing SWEI approaches to improve their accuracy for cervical assessment.

Mechanical strain induced phospho-proteomic signaling in uterine smooth muscle cells

Mechanical strain associated with the expanding uterus correlates with increased preterm birth rates. Mechanical signals result in a cascading network of protein phosphorylation events. These signals direct cellular activities and may lead to changes in contractile phenotype and calcium signaling. In this study, the complete phospho-proteome of uterine smooth muscle cells subjected to mechanical strain for 5 min was compared to un-strained controls. Statistically significant, differential phosphorylation events were annotated by Ingenuity Pathway Analysis to elucidate mechanically induced phosphorylation networks. Mechanical strain leads to the direct activation of ERK1/2, HSPB1, and MYL9, in addition to phosphorylation of PAK2, vimentin, DOCK1, PPP1R12A, and PTPN11 at previously unannotated sites. These results suggest a novel network reaction to mechanical strain and reveal proteins that participate in the activation of contractile mechanisms leading to preterm labor.

Computer modeling tools to understand the causes of preterm birth

The mechanical integrity of the soft tissue structures supporting the fetus may play a role in maintaining a healthy pregnancy and triggering the onset of labor. Currently, the level of mechanical loading on the uterus, cervix, and fetal membranes during pregnancy is unknown, and it is hypothesized that the over-stretch of these tissues contributes to the premature onset of contractility, tissue remodeling, and membrane rupture, leading to preterm birth. The purpose of this review article is to introduce and discuss engineering analysis tools to evaluate and predict the mechanical loads on the uterus, cervix, and fetal membranes. Here we will explore the potential of using computational biomechanics and finite element analysis to study the causes of preterm birth and to develop a diagnostic tool that can predict gestational outcome. We will define engineering terms and identify the potential engineering variables that could be used to signal an abnormal pregnancy. We will discuss the translational ability of computational models for the better management of clinical patients. We will also discuss the process of model validation and the limitations of these models. We will explore how we can borrow from parallel engineering fields to push the boundary of patient care so that we can work toward eliminating preterm birth.

A Parameterized Ultrasound-Based Finite Element Analysis of the Mechanical Environment of Pregnancy

Preterm birth is the leading cause of childhood mortality and can lead to health risks in survivors. The mechanical functions of the uterus, fetal membranes, and cervix have dynamic roles to protect the fetus during gestation. To understand their mechanical function and relation to preterm birth, we built a three-dimensional parameterized finite element model of pregnancy. This model is generated by an automated procedure that is informed by maternal ultrasound measurements. A baseline model at 25 weeks of gestation was characterized, and to visualize the impact of cervical structural parameters on tissue stretch, we evaluated the model sensitivity to (1) anterior uterocervical angle, (2) cervical length, (3) posterior cervical offset, and (4) cervical stiffness. We found that cervical tissue stretching is minimal when the cervical canal is aligned with the longitudinal uterine axis, and a softer cervix is more sensitive to changes in the geometric variables tested.

The impact of uterine immaturity on obstetrical syndromes during adolescence

Pregnant nulliparous adolescents are at increased risk, inversely proportional to their age, of major obstetric syndromes, including preeclampsia, fetal growth restriction, and preterm birth. Emerging evidence indicates that biological immaturity of the uterus accounts for the increased incidence of obstetrical disorders in very young mothers, possibly compounded by sociodemographic factors associated with teenage pregnancy. The endometrium in most newborns is intrinsically resistant to progesterone signaling, and the rate of transition to a fully responsive tissue likely determines pregnancy outcome during adolescence. In addition to ontogenetic progesterone resistance, other factors appear important for the transition of the immature uterus to a functional organ, including estrogen-dependent growth and tissue-specific conditioning of uterine natural killer cells, which plays a critical role in vascular adaptation during pregnancy. The perivascular space around the spiral arteries is rich in endometrial mesenchymal stem-like cells, and dynamic changes in this niche are essential to accommodate endovascular trophoblast invasion and deep placentation. Here we evaluate the intrinsic (uterine-specific) mechanisms that predispose adolescent mothers to the great obstetrical syndromes and discuss the convergence of extrinsic risk factors that may be amenable to intervention.

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.

Is myometrial inflammation a cause or a consequence of term human labour?

Myometrial inflammation is thought to have a pivotal role in the onset of term and some forms of preterm labour. This is based on the comparison of samples taken from women undergoing term elective CS prior to the onset of labour with those taken from women in established labour. Consequently, it is not clear whether myometrial inflammation is a cause or a consequence of labour. Our objective is to test the hypothesis that myometrial inflammation is a consequence of the onset of labour. To test this hypothesis, we have obtained myometrial samples from women at various stages of pregnancy and spontaneous labour and studied the activation of the AP-1 (c-Jun) and NFκB (p65) systems, cytokine mRNA expression and protein levels and inflammatory cell infiltration and activation. We found that the activation of p65 declined from preterm to term not in labour samples and thereafter increased in early and established labour. Cytokine mRNA expression and protein levels increased in established labour only. Using flow cytometry of myometrial tissue, we found that the number of neutrophils did increase with the onset of labour, but on tissue section, these were seen to be intravascular and not infiltrating into the myometrium. These data suggest that myometrial inflammation is a consequence rather than a cause of term labour.

Biomechanics of the human uterus

The appropriate biomechanical function of the uterus is required for the execution of human reproduction. These functions range from aiding the transport of the embryo to the implantation site, to remodeling its tissue walls to host the placenta, to protecting the fetus during gestation, to contracting forcefully for a safe parturition and postpartum, to remodeling back to its nonpregnant condition to renew the cycle of menstruation. To serve these remarkably diverse functions, the uterus is optimally geared with evolving and contractile muscle and tissue layers that are cued by chemical, hormonal, electrical, and mechanical signals. The relationship between these highly active biological signaling mechanisms and uterine biomechanical function is not completely understood for normal reproductive processes and pathological conditions such as adenomyosis, endometriosis, infertility and preterm labor. Animal studies have illuminated the rich structural function of the uterus, particularly in pregnancy. In humans, medical imaging techniques in ultrasound and magnetic resonance have been combined with computational engineering techniques to characterize the uterus in vivo, and advanced experimental techniques have explored uterine function using ex vivo tissue samples. The collective evidence presented in this review gives an overall perspective on uterine biomechanics related to both its nonpregnant and pregnant function, highlighting open research topics in the field. Additionally, uterine disease and infertility are discussed in the context of tissue injury and repair processes and the role of computational modeling in uncovering etiologies of disease. WIREs Syst Biol Med 2017, 9:e1388. doi: 10.1002/wsbm.1388 For further resources related to this article, please visit the WIREs website.

Mapping out p38MAPK

To generate new hypotheses, sometimes a "systems" approach is needed. In this review, I focus on the mitogen-activated kinase p38 because it has been recently shown to play an important role in the developmental programing and senescence of normal and stressed reproductive tissues. What follows is an overview of (i) pathways of p38 activation and their involvement in basic biological processes, (ii) evidence that p38 is involved in the homeostasis of reproductive tissues, (iii) how focus on p38 can be incorporated into investigation of normal and stressed pregnancies. Existence of excellent reviews will be mentioned as well as relevant animal models.

Myometrial cytokines and their role in the onset of labour

Human labour is an inflammatory event, physiologically driven by an interaction between hormonal and mechanical factors and pathologically associated with infection, bleeding and excessive uterine stretch. The initiation and communicators of inflammation is still not completely understood; however, a key role for cytokines has been implicated. We summarise the current understanding of the nature and role of cytokines, chemokines and hormones and their involvement in signalling within the myometrium particularly during labour.

Hemorrhage is the most common cause of neonatal mortality in patients with sacrococcygeal teratoma

BACKGROUND

A small percentage of neonates with sacrococcygeal teratoma die shortly after birth from hemorrhagic complications. The incidence of and risk factors associated with hemorrhagic mortality are unknown. In this multicenter study we determined the incidence of early death in neonates born with SCT and evaluated potential risk factors for hemorrhagic mortality.

METHODS

235 children with SCT treated from 1970 to 2010 in the Netherlands were retrospectively included. The following candidate risk factors for hemorrhagic mortality were examined: sex, prematurity, Altman type, tumor volume, tumor histology, necessity of emergency operation and time of diagnosis.

RESULTS

Eighteen patients (7.7%) died at a median age of 163.5days (range 1.7-973days). Nine patients died of a malignancy. Nine others (3.8%) died postnatally (age 1-27days), six even within two days after birth. In seven of these nine patients death was related to tumor-hemorrhage and/or circulatory failure. Risk factors for hemorrhagic mortality were prematurity, tumor volume>1000cm³ and performance of an emergency operation.

CONCLUSIONS

Hemorrhagic mortality of neonates with SCT is relatively high (3.8%) representing almost 70% of the overall mortality in the neonatal period. High-output cardiac failure, internal tumor hemorrhage and perioperative bleeding were the most common causes of early death and were all strongly associated with larger tumor sizes.

LEVEL-OF-EVIDENCE RATING

II (Retrospective study).

Group B Streptococcus circumvents neutrophils and neutrophil extracellular traps during amniotic cavity invasion and preterm labor

Preterm birth is a leading cause of neonatal morbidity and mortality. Although microbial invasion of the amniotic cavity (MIAC) is associated with the majority of early preterm births, the temporal events that occur during MIAC and preterm labor are not known. Group B Streptococci (GBS) are β-hemolytic, gram-positive bacteria, which commonly colonize the vagina but have been recovered from the amniotic fluid in preterm birth cases. To understand temporal events that occur during MIAC, we utilized a unique chronically catheterized nonhuman primate model that closely emulates human pregnancy. This model allows monitoring of uterine contractions, timing of MIAC and immune responses during pregnancy-associated infections. Here, we show that adverse outcomes such as preterm labor, MIAC, and fetal sepsis were observed more frequently during infection with hemolytic GBS when compared to nonhemolytic GBS. Although MIAC was associated with systematic progression in chorioamnionitis beginning with chorionic vasculitis and progressing to neutrophilic infiltration, the ability of the GBS hemolytic pigment toxin to induce neutrophil cell death and subvert killing by neutrophil extracellular traps (NETs) in placental membranes in vivo facilitated MIAC and fetal injury. Furthermore, compared to maternal neutrophils, fetal neutrophils exhibit decreased neutrophil elastase activity and impaired phagocytic functions to GBS. Collectively, our studies demonstrate how a unique bacterial hemolytic lipid toxin enables GBS to circumvent neutrophils and NETs in placental membranes to induce fetal injury and preterm labor.

The greater risk of preterm birth in triplets is mirrored by a more rapid cervical shortening along gestation

BACKGROUND

The risk of preterm birth increases with plurality. However, data are limited about the role of cervical length in triplet pregnancies and how the greater predisposition for preterm birth in triplet pregnancies, compared with twin pregnancies, is reflected by cervical length. Specifically, it is unclear whether the greater predisposition of triplet pregnancies for preterm birth is reflected by a more rapid cervical shortening during gestation compared with twin pregnancies (and therefore a shorter cervical length at any given gestational age), by a greater risk for preterm birth per given cervical length at any given gestational age, or both.

OBJECTIVE

The purpose of the study was to compare the rate of cervical shortening during gestation and the correlation between cervical length and gestational age at birth in asymptomatic women with triplet vs twin pregnancies.

STUDY DESIGN

This was a retrospective study of women with triplet or twin pregnancies who were who were observed in a tertiary center who underwent serial sonographic measurement of cervical length from 16-32 weeks gestation. Change in cervical length during gestation and relationship of cervical length with gestational age at birth were compared between the triplets and twins groups.

RESULTS

A total of 431 measurements of cervical length from 86 women with triplets was analyzed and compared with 2826 measurements of cervical length from 441 women with twins. The rate of cervical shortening among triplet pregnancies was higher than among twin pregnancies starting from 18 weeks of gestation (slope of regression line, -1.297 vs -0.907; P < .001). Similarly, the proportion of women with cervical length of <25 mm or 15 mm was higher among triplet pregnancies than among twin pregnancies (34.0% vs 21.0% [P < .001] and 16.7% vs 8.4% [P = .001]), respectively. For any given cervical length measured after 22 weeks of gestation, the associated gestational length at birth in triplet pregnancies was lower by 2.7 weeks on average compared with twin pregnancies (P < .001).

CONCLUSION

The higher rate of preterm birth in triplet pregnancies, compared with twin pregnancies, is reflected by both a more rapid cervical shortening during gestation and a lower gestational age at birth per any given cervical length.