A standardized template for clinical studies in preterm birth

Title: β3 Adrenergic Receptor Signaling in the Human Myometrium

Preterm labor leading to preterm birth is the leading cause of infant morbidity and mortality. Although β2 adrenergic agonists fail to provide adequate tocolysis, the expression of the β3 adrenergic receptor in myometrium and its unique signaling suggest a role for β3 agonist in the management of preterm labor. Western blot analysis showed that the β3 adrenergic receptor expression increased in human pregnancy myometrium compared to nonpregnant tissues (p < 0.0001). There was no difference in β3 adrenergic receptor expression throughout pregnancy (p > 0.05). The addition of the β3 agonist mirabegron in the tissue bath relaxed oxytocin contracted myometrium with an EC₅₀ of 41.5 µM. Relaxation was partially blocked by the addition of the eNOS blocker Nω-nitro-L-arginine, or the large conductance potassium channel blocker paxilline. Combination of Nω-nitro-L-arginine and paxilline prevented mirabegron-mediated relaxation. Imaging revealed that the β3 adrenergic receptors are expressed by both myocyte and microvascular endothelial cells isolated from human myometrium. Nitric oxide production measured by 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate revealed that mirabegron stimulated nitric oxide production in myometrial endothelial cells. These data suggest that both endothelial and smooth muscle cells contribute to relaxation through disparate signaling pathways. Repurposing of approved medications tested in human myometrium as uterine tocolytics can advance prevention of preterm birth. These data argue that further examination of β3 adrenergic receptor signaling in myometrium may reveal mirabegron as a useful tocolytic in combination tocolysis regimens.

Caesarean birth and risk of subsequent preterm birth: a retrospective cohort study

OBJECTIVE

To determine the risk of spontaneous and medically indicated preterm birth associated with mode of birth in previous term-born pregnancy.

DESIGN

Retrospective cohort study.

SETTING

Two UK maternity units.

POPULATION OR SAMPLE

A total of 16 340 women with first two consecutive singleton births and the first birth at term.

METHODS

Retrospective cohort study using routinely collected clinical data.

MAIN OUTCOME MEASURES

Incidence of spontaneous preterm birth and medically indicated preterm birth at less than 37 weeks of gestation after term birth, in relation to mode of birth in first pregnancy. Subgroup analysis on cervical dilatation at the time of first caesarean birth.

RESULTS

Compared with vaginal birth, emergency caesarean birth at full dilatation was associated with an increase in spontaneous preterm birth (2.3% vaginal birth versus 4.5% full dilatation caesarean; adjusted odds ratio [aOR] 3.29, 95% CI 2.02-5.13, P < 0.001). Elective caesarean, emergency caesarean at <4 cm dilatation, and emergency caesarean at 4-9 cm dilatation were associated with increased medically indicated preterm birth (0.8% vaginal births versus 1.9% elective caesarean, 3.3% <4 cm caesarean, 1.3% 4-9 cm caesarean; aOR 2.30, 95% CI 1.19-4.15, P = 0.009; aOR 4.68, 95% CI 2.98-7.24, P < 0.001; and aOR 2.43, 95% CI 1.43-4.00, P = 0.001, respectively).

CONCLUSIONS

Term caesarean in the first stage of labour or performed prelabour is associated with medically indicated preterm birth. Term caesarean in the second stage of labour is associated with spontaneous preterm birth.

TWEETABLE ABSTRACT

Caesarean in the second stage of labour is associated with spontaneous preterm birth.

Matrix metalloproteinases 2 and 9 are elevated in human preterm laboring uterine myometrium and exacerbate uterine contractility†

Matrix metalloproteinases 2 and 9 (MMP2/9) have previously been shown to be elevated in serum and amniotic fluid from women undergoing preterm birth. We performed experiments to determine the effects of MMP2/9 on uterine contraction and birth timing. Pregnant mice were injected daily with 50 mg/kg of SB-3CT or vehicle control beginning on gestational day 14-18 to determine if MMP2/9 inhibition would affect parturition timing. MMP2/9 expression in human myometrial tissue was determined by Simple Western (Wes) and semiquantitative western blot. Purified MMP2/9 and SB-3CT inhibitor were added to human myometrial strips to determine the effects of MMP2/9 on oxytocin-induced uterine contraction. Parturition was delayed in mice treated with MMP2/9 inhibitor SB-3CT. MMP2/9 protein levels were elevated in preterm laboring uterine myometrium. Gelatinase activity was confirmed in cell extracts and supernatants from immortalized and primary human uterine myometrial cells in culture. Addition of purified MMP2/9 increased the oxytocin-induced contractile response in myometrial tissue strips from pregnant women. In contrast, addition of the MMP2/9 inhibitor SB-3CT decreased the contractile response to oxytocin in a dose-dependent manner. These results suggest abnormal MMP2/9 expression affects the contractile state of the uterine myometrium to promote parturition and that MMP2/9 inhibition attenuates this effect.

Postal recruitment for genetic studies of preterm birth: A feasibility study

Background: Preterm birth (PTB) represents the leading cause of neonatal death. Large-scale genetic studies are necessary to determine genetic influences on PTB risk, but prospective cohort studies are expensive and time-consuming. We investigated the feasibility of retrospective recruitment of post-partum women for efficient collection of genetic samples, with self-collected saliva for DNA extraction from themselves and their babies, alongside self-recollection of pregnancy and birth details to phenotype PTB.

Methods: 708 women who had participated in the OPPTIMUM trial (a randomised trial of progesterone pessaries to prevent PTB [ISRCTN14568373]) and consented to further contact were invited to provide self-collected saliva from themselves and their babies. DNA was extracted from Oragene OG-500 (adults) and OG-575 (babies) saliva kits and the yield measured by Qubit. Samples were analysed using a panel of Taqman single nucleotide polymorphism (SNP) assays. A questionnaire designed to meet the minimum data set required for phenotyping PTB was included. Questionnaire responses were transcribed and analysed for concordance with prospective trial data using Cohen’s kappa ( k).

Results: Recruitment rate was 162/708 (23%) for self-collected saliva samples and 157/708 (22%) for questionnaire responses. 161 samples from the mother provided DNA with median yield 59.0µg (0.4-148.9µg). 156 samples were successfully genotyped (96.9%). 136 baby samples had a median yield 11.5µg (0.1-102.7µg); two samples failed DNA extraction. 131 baby samples (96.3%) were successfully genotyped. Concordance between self-recalled birth details and prospective birth details was excellent ( k>0.75) in 4 out of 10 key fields for phenotyping PTB (mode of delivery, labour onset, ethnicity and maternal age at birth).

Conclusion: This feasibility study demonstrates that self-collected DNA samples from mothers and babies were sufficient for genetic analysis but yields were variable. Self-recollection of pregnancy and birth details was inadequate for accurately phenotyping PTB, highlighting the need for alternative strategies for investigating genetic links with PTB.

Postal recruitment for genetic studies of preterm birth: A feasibility study

Background: Preterm birth (PTB) represents the leading cause of neonatal death. Large-scale genetic studies are necessary to determine genetic influences on PTB risk, but prospective cohort studies are expensive and time-consuming. We investigated the feasibility of retrospective recruitment of post-partum women for efficient collection of genetic samples, with self-collected saliva for DNA extraction from themselves and their babies, alongside self-recollection of pregnancy and birth details to phenotype PTB. Methods: 708 women who had participated in the OPPTIMUM trial (a randomised trial of progesterone pessaries to prevent PTB [ISRCTN14568373]) and consented to further contact were invited to provide self-collected saliva from themselves and their babies. DNA was extracted from Oragene OG-500 (adults) and OG-575 (babies) saliva kits and the yield measured by Qubit. Samples were analysed using a panel of Taqman single nucleotide polymorphism (SNP) assays. A questionnaire designed to meet the minimum data set required for phenotyping PTB was included. Questionnaire responses were transcribed and analysed for concordance with prospective trial data. Results: Recruitment rate was 162/708 (23%) for self-collected saliva samples and 157/708 (22%) for questionnaire responses. 161 samples from the mother provided DNA with median yield 59.0µg (0.4-148.9µg). 156 samples were successfully genotyped (96.9%). 136 baby samples had a median yield 11.5µg (0.1-102.7µg); two samples failed DNA extraction. 131 baby samples (96.3%) were successfully genotyped. Concordance between self-recalled birth details and prospective birth details ranged from 55 – 99%, median 86%. The highest rates of concordance were found for mode of birth (154/156 [99%]), smoking status (151/157 [96%]) and ethnicity (149/156 [96%]). Conclusion: This feasibility study demonstrates that self-collected DNA samples from mothers and babies were sufficient for genetic analysis but yields were variable. Self-recollection of pregnancy and birth details was inadequate for accurately phenotyping PTB, highlighting the need for alternative strategies for investigating genetic links with PTB.

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

BACKGROUND

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

The Zambian Preterm Birth Prevention Study (ZAPPS): Cohort characteristics at enrollment

Background: Sub-Saharan Africa bears a disproportionate burden of preterm birth and other adverse outcomes. A better understanding of the demographic, clinical, and biologic underpinnings of these adverse outcomes is urgently needed to plan interventions and inform new discovery.  Methods: The Zambian Preterm Birth Prevention Study (ZAPPS) is a prospective observational cohort established at the Women and Newborn Hospital (WNH) in Lusaka, Zambia. We recruit pregnant women from district health centers and the WNH and offer ultrasound examination to determine eligibility. Participants receive routine obstetrical care, lab testing, midtrimester cervical length measurement, and serial fetal growth monitoring. At delivery, we assess gestational age, birthweight, vital status, and sex and assign a delivery phenotype. We collect blood, urine, and vaginal swab specimens at scheduled visits and store them in an on-site biorepository. In September 2017, enrollment of the ZAPPS Phase 1-the subject of this report-was completed. Phase 2, which is limited to HIV-uninfected women, reopened in January 2018.  Results: Between August 2015 and September 2017, we screened 1784 women, of whom 1450 (81.2%) met inclusion criteria and were enrolled. The median age at enrollment was 27 years (IQR 23-32) and median gestational age was 16 weeks (IQR 13-18). Among women with a previous pregnancy (n=1042), 19% (n=194) reported a prior miscarriage.  Among parous women (n=992), 41% (n=411) reported a prior preterm birth and 14% (n=126) reported a prior stillbirth. The HIV seroprevalence was 24%. Discussion: We have established a large cohort of pregnant women and newborns at the WNH to characterize the determinants of adverse birth outcomes in Lusaka, Zambia. Our overarching goal is to elucidate biological mechanisms in an effort to identify new strategies for early detection and prevention of adverse outcomes. We hope that findings from this cohort will help guide future studies, clinical care, and policy.

Transcriptomic analysis of fetal membranes reveals pathways involved in preterm birth

Background

Preterm birth (PTB), defined as infant delivery before 37 weeks of completed gestation, results from the interaction of both genetic and environmental components and constitutes a complex multifactorial syndrome. Transcriptome analysis of PTB has proven challenging because of the multiple causes of PTB and the numerous maternal and fetal gestational tissues that must interact to facilitate parturition. The transcriptome of the chorioamnion membranes at the site of rupture in PTB and term fetuses may reflect the molecular pathways of preterm labor.

Methods

In this work, chorioamnion membranes from severe preterm and term fetuses were analyzed using RNA sequencing. Functional annotations and pathway analysis of differentially expressed genes were performed with the GAGE and GOSeq packages. A subset of differentially expressed genes in PTB was validated in a larger cohort using qRT-PCR and by comparing our results with genes and pathways previously reported in the literature.

Results

A total of 270 genes were differentially expressed (DE): 252 were upregulated and 18 were down-regulated in severe preterm births relative to term births. Inflammatory and immunological pathways were upregulated in PTB. Both types of pathways were previously suggested to lead to PTB. Pathways that were not previously reported in PTB, such as the hemopoietic pathway, appeared upregulated in preterm membranes. A group of 18 downregulated genes discriminated between term and severe preterm cases. These genes potentially characterize a severe preterm transcriptome pattern and therefore are candidate genes for understanding the syndrome. Some of the downregulated genes are involved in the nervous system, morphogenesis (WNT1, DLX5, PAPPA2) and ion channel complexes (KCNJ16, KCNB1), making them good candidates as biomarkers of PTB.

Conclusions

The identification of this DE gene pattern will help with the development of a multi-gene disease classifier. These markers were generated in an admixed South American population in which PTB has a high incidence. Since the genetic background may differentially impact different populations, it is necessary to include populations such as those from South America and Africa, which are usually excluded from high-throughput approaches. These classifiers should be compared to those in other populations to obtain a global landscape of PTB.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0498-3) contains supplementary material, which is available to authorized users.

History of the establishment of the Preterm Birth international collaborative (PREBIC)

INTRODUCTION

The primary aim of PREBIC is to assess the underlying mechanisms and developing strategies for preterm birth (PTB) prevention.

MATERIALS AND METHODS

We used concept mapping and logic models to track goals. This paper reviews our progress over 13 years using working group activities, research developments, guest speakers, and publications.

RESULTS

Using interactions between genetics, environment, and behaviors we identified complex interactions between biological systems. PREBIC determined that epidemiology and biomarkers should be an initial focus. In 2005, we initiated presentations by young investigators, yearly satellite meetings, working groups including nutrition and inflammation, assessment of clinical trials, and accepted an invitation by the WHO to begin yearly meetings in Geneva.

DISCUSSION

PREBIC used epidemiology to identify PTB factors and complex pathways. Candidate genes are associated with the environment, behavior (stress), obesity, inflammation and insulin resistance. Epigenetic changes and production of proteins can be used as biomarkers to define risk. Subsequently, we found risk factors for PTB that were also associated with the risk of cardiovascular disease (CVD) of the mother. Tanz et al. (2017) found that a history of PTB is independently predictive of CVD later in life and suggested that a modest proportion of PTB-CVD association was accounted by CVD risk factors, many of which have been identified in this paper.

CONCLUSION

Our findings support a relationship between genes, environment, behaviors and risk of CVD in women. The next several years must assess which factors are modifiable early in life and before pregnancy to prevent PTB.

S-Nitrosoglutathione Reductase Underlies the Dysfunctional Relaxation to Nitric Oxide in Preterm Labor

Tocolytics show limited efficacy to prevent preterm delivery. In uterine smooth muscle cGMP accumulation following addition of nitric oxide (NO) has little effect on relaxation suggesting a role for protein S-nitrosation. In human myometrial tissues from women in labor at term (TL), or spontaneously in labor preterm (sPTL), direct stimulation of soluble guanylyl cyclase (sGC) fails to relax myometrium, while the same treatment relaxes vascular smooth muscle completely. Unlike term myometrium, effects of NO are not only blunted in sPTL, but global protein S-nitrosation is also diminished, suggesting a dysfunctional response to NO-mediated protein S-nitrosation. Examination of the enzymatic regulator of endogenous S-nitrosoglutathione availability, S-nitrosoglutathione reductase, reveals increased expression of the reductase in preterm myometrium associated with decreased total protein S-nitrosation. Blockade of S-nitrosoglutathione reductase relaxes sPTL tissue. Addition of NO donor to the actin motility assay attenuates force. Failure of sGC activation to mediate relaxation in sPTL tissues, together with the ability of NO to relax TL, but not sPTL myometrium, suggests a unique pathway for NO-mediated relaxation in myometrium. Our results suggest that examining the action of S-nitrosation on critical contraction associated proteins central to the regulation of uterine smooth muscle contraction can reveal new tocolytic targets.

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.

Calciprotein particles as potential etiologic agents of idiopathic preterm birth

Preterm birth (PTB) is a leading cause of neonatal morbidity and mortality and is often preceded by preterm premature rupture of the membranes (PPROM) without an identifiable cause. Pathological calcification, the deposition of hydroxyapatite (HA) in nonskeletal tissues, has been implicated in degenerative diseases including atherosclerosis and aneurism rupture. Among pathogenic mechanisms, the aberrant aggregation of HA into calciprotein particles (CPPs) and the HA-induced differentiation of mesenchymal cells into osteoblasts (ectopic osteogenesis) have been implicated. We explored the hypothesis that CPPs form in human amniotic fluid (AF), deposit in fetal membranes, and are linked mechanistically to pathogenic pathways favoring PTB. We demonstrated that fetal membranes from women with idiopathic PPROM frequently show evidence of ectopic calcification and expression of osteoblastic differentiation markers. Concentrations of fetuin-A, an endogenous inhibitor of ectopic calcification, were decreased in AF of idiopathic PPROM cases, which reflected their reduced functional capacity to inhibit calcification. Using long-term cultures of sterile AF, we demonstrated coaggregation of HA with endogenous proteins, including fetuin-A. The fetuin-HA aggregates exhibited progressive growth in vitro in a pattern similar to CPPs. When applied to amniochorion explants, AF-derived CPPs induced structural and functional pathological effects recapitulating those noted for PPROM. Our results demonstrate that disruption of protein-mineral homeostasis in AF stimulates the formation and deposition of CPPs, which may represent etiologic agents of idiopathic PPROM. Therapeutic or dietary interventions aimed at maintaining the balance between endogenous HA formation and fetuin reserve in pregnant women may therefore have a role in preventing PTB.

Translational Systems Pharmacology Studies in Pregnant Women

Pregnancy involves rapid physiological adaptation and complex interplay between mother and fetus. New analytic technologies provide large amounts of genomic, proteomic, and metabolomics data. The integration of these data through bioinformatics, statistical, and systems pharmacology techniques can improve our understanding of the mechanisms of normal maternal physiologic changes and fetal development. New insights into the mechanisms of pregnancy‐related disorders, such as preterm birth (PTB), may lead to the development of new therapeutic interventions and novel biomarkers.

Increased expression of toll-like receptors 2 and 9 is associated with reduced DNA methylation in spontaneous preterm labor

The cause of spontaneous preterm labor (sPTL) is not known, but it could be due to epigenetic alterations that increase the sensitivity of decidual tissue to inflammatory stimuli. We collected decidual tissue from women at term not in labor (TNL), women at term in labor (TL), and women with sPTL. Illumina Infinium HumanMethylation450 BeadChip analysis revealed significantly reduced DNA methylation for TLR-2 and TLR-9 in sPTL as compared to TL. Immunohistochemical staining documented significantly increased expression of TLR-2 and TLR-9 in decidual tissue of women with sPTL as compared to TL or TNL. TLR expression was not present in decidual cells, but localized to tissue leukocytes as revealed by staining for CD14, a macrophage antigen, and neutrophil elastase. Microarray analysis of inflammatory genes to assess innate immune response demonstrated marked increases in expression of inflammatory cytokines and chemokines in women with TL as compared to TNL. However, when sPTL was compared to TL, there was a further increase in inflammatory cytokines, and a remarkable increase in neutrophil chemokines. These results suggest that epigenetic mechanisms could play a role in increasing leukocyte infiltration, and increasing the sensitivity of decidual tissue to inflammatory stimuli that could precipitate labor prematurely.

Interleukin-1 Receptor Antagonist Polymorphism and Birth Timing: Pathway Analysis Among African American Women

BACKGROUND

Timing of birth is a major determinant of newborn health. African American women are at increased risk for early birth, particularly via the inflammatory pathway. Variants of the IL1RN gene, which encode the interleukin-1 receptor antagonist (IL-1Ra) protein, are implicated in early birth. The biological pathways linking these variables remain unclear. Evidence also suggests that inflammatory pathways differ by race; however, studies among African American women are lacking.

OBJECTIVES

We assessed whether an IL1RN variant was associated with timing of birth among African American women and whether this relationship was mediated by lower anti-inflammatory IL-1Ra production or related to a decrease in inhibition of proinflammatory IL-1β production.

METHODS

A candidate gene study using a prospective cohort design was used. We collected blood samples at 28-32 weeks of gestation among African American women experiencing an uncomplicated pregnancy (N = 89). IL1RN single-nucleotide polymorphism (SNP) rs2637988 was genotyped, and lipopolysaccharide-stimulated IL-1Ra and IL-1β production was quantified. Medical record review determined timing of birth.

RESULTS

Women with GG genotype gave birth earlier than women with AA/AG genotypes (b* = .21, p = .04). There was no indirect effect of IL1RN SNP rs2637988 allele status on timing of birth through IL-1Ra production, as evidenced by a nonsignificant product of coefficients in mediational analyses (ab = .006, 95% CI [-0.05, 0.13]). Women with GG genotype showed less inhibition of IL-1β production for a unit positive difference in IL-1Ra production than women with AA/AG genotypes (b* = .93, p = .03). Greater IL-1β production at 28-32 weeks of pregnancy was marginally associated with earlier birth (b* = .21, p = .05).

DISCUSSION

Women with GG genotype may be at risk for earlier birth because of diminished IL-1β inhibition, allowing for initiation of a robust inflammatory response upon even mild immune challenge. Study of inflammatory contributions to early birth among African American women may be key to identifying potential prognostic markers of risk and targeted preventive interventions.

Preterm Birth: A Prominent Risk Factor for Low Apgar Scores

OBJECTIVE

To determine predictive risk factors for Apgar scores < 7 at 5 minutes at two hospitals providing tertiary care and secondary care, respectively.

METHODS

A retrospective registry cohort study of 21126 births (2006-2010) using data from digital medical records. Risk factors were analyzed by logistic regression analyses.

RESULTS

AS(5 min) < 7 was multivariately associated with the following: preterm birth; gestational week 32 + 0-36 + 6, OR = 3.9 (95% CI 2.9-5.3); week 28 + 0-31 + 6, OR = 8 (5-12); week < 28 + 0, OR = 15 (8-29); postterm birth, OR = 2.0 (1.7-2.3); multiple pregnancy, OR = 3.53 (1.79-6.96); previous cesarean section, OR = 3.67 (2.31-5.81); BMI 25-29, OR = 1.30 (1.09-1.55); BMI ≥ 30  OR = 1.70 (1.20-2.41); nonnormal CTG at admission, OR = 1.98 (1.48-2.66). ≥ 1-para was associated with a decreased risk for AS(5 min) < 7, OR = 0.34 (0.25-0.47). In the univariate logistic regression analysis AS(5 min) < 7 was associated with tertiary level care, OR = 1.48 (1.17-1.87); however, in the multivariate analysis there was no significant difference.

CONCLUSION

A number of partially preventable risk factors were identified, preterm birth being the most evident. Further, no significant difference between the two hospital levels regarding the risk for low Apgar scores was detected.

Gestational tissue transcriptomics in term and preterm human pregnancies: a systematic review and meta-analysis

BACKGROUND

Preterm birth (PTB), or birth before 37 weeks of gestation, is the leading cause of newborn death worldwide. PTB is a critical area of scientific study not only due to its worldwide toll on human lives and economies, but also due to our limited understanding of its pathogenesis and, therefore, its prevention. This systematic review and meta-analysis synthesizes the landscape of PTB transcriptomics research to further our understanding of the genes and pathways involved in PTB subtypes.

METHODS

We evaluated published genome-wide pregnancy studies across gestational tissues and pathologies, including those that focus on PTB, by performing a targeted PubMed MeSH search and systematically reviewing all relevant studies.

RESULTS

Our search yielded 2,361 studies on gestational tissues including placenta, decidua, myometrium, maternal blood, cervix, fetal membranes (chorion and amnion), umbilical cord, fetal blood, and basal plate. Selecting only those original research studies that measured transcription on a genome-wide scale and reported lists of expressed genetic elements identified 93 gene expression, 21 microRNA, and 20 methylation studies. Although 30 % of all PTB cases are due to medical indications, 76 % of the preterm studies focused on them. In contrast, only 18 % of the preterm studies focused on spontaneous onset of labor, which is responsible for 45 % of all PTB cases. Furthermore, only 23 of the 10,993 unique genetic elements reported to be transcriptionally active were recovered 10 or more times in these 134 studies. Meta-analysis of the 93 gene expression studies across 9 distinct gestational tissues and 29 clinical phenotypes showed limited overlap of genes identified as differentially expressed across studies.

CONCLUSIONS

Overall, profiles of differentially expressed genes were highly heterogeneous both between as well as within clinical subtypes and tissues as well as between studies of the same clinical subtype and tissue. These results suggest that large gaps still exist in the transcriptomic study of specific clinical subtypes as well in the generation of the transcriptional profile of well-studied clinical subtypes; understanding the complex landscape of prematurity will require large-scale, systematic genome-wide analyses of human gestational tissues on both understudied and well-studied subtypes alike.

A transdisciplinary approach to the decision-making process in extreme prematurity

Background

A wide range of dilemmas encountered in the health domain can be addressed more efficiently by a transdisciplinary approach. The complex context of extreme prematurity, which is raising important challenges for caregivers and parents, warrants such an approach.

Methods

In the present work, experts from various disciplinary fields, namely biomedical, epidemiology, psychology, ethics, and law, were enrolled to participate in a reflection. Gathering a group of experts could be very demanding, both in terms of time and resources, so we created a web-based discussion forum to facilitate the exchanges. The participants were mandated to solve two questions: “Which parameters should be considered before delivering survival care to a premature baby born at the threshold of viability?” and “Would it be acceptable to give different information to parents according to the sex of the baby considering that outcome differences exist between sexes?”

Results

The discussion forum was performed over a period of nine months and went through three phases: unidisciplinary, interdisciplinary and transdisciplinary, which required extensive discussions and the preparation of several written reports. Those steps were successfully achieved and the participants finally developed a consensual point of view regarding the initial questions. This discussion board also led to a concrete knowledge product, the publication of the popularized results as an electronic book.

Conclusions

We propose, with our transdisciplinary analysis, a relevant and innovative complement to existing guidelines regarding the decision-making process for premature infants born at the threshold of viability, with an emphasis on the respective responsabilities of the caregivers and the parents.

Epigenetics of human myometrium: DNA methylation of genes encoding contraction-associated proteins in term and preterm labor

Preterm birth involves the interaction of societal and environmental factors potentially modulating the length of gestation via the epigenome. An established form of epigenetic regulation is DNA methylation where promoter hypermethylation is associated with gene repression. We hypothesized we would find differences in DNA methylation in the myometrium of women with preterm labor of different phenotypes versus normal term labor. Myometrial tissue was obtained at cesarean section at term with or without labor, preterm without labor, idiopathic preterm labor, and twin gestations with labor. Genomic DNA was isolated, and samples in each group were combined and analyzed on a NimbleGen 2.1M human DNA methylation array. Differences in methylation from -8 to +3 kb of transcription start sites of 22 contraction-associated genes were determined. Cytosine methylation was not present in CpG islands of any gene but was present outside of CpG islands in shores and shelves in 19 genes. No differential methylation was found across the tissue groups for six genes (PTGES3L, PTGER2, PTGER4, PTGFRN, ESR2, and GJA1). For 13 genes, differential methylation occurred in several patterns between tissue groups. We find a correlation between hypomethylation and increased mRNA expression of PTGES/mPGES-1, indicating potential functional relevance of methylation, but no such correlation for PTGS2/COX-2, suggesting other regulatory mechanisms for PTGS2 at labor. The majority of differential DNA methylation of myometrial contraction-associated genes with different labor phenotypes occurs outside of CpG islands in gene promoters, suggesting that the entirety of DNA methylation across the genome should be considered.

Role of serine-threonine phosphoprotein phosphatases in smooth muscle contractility

The degree of phosphorylation of myosin light chain 20 (MLC20) is a major determinant of force generation in smooth muscle. Myosin phosphatases (MPs) contain protein phosphatase (PP) 1 as catalytic subunits and are the major enzymes that dephosphorylate MLC20. MP regulatory targeting subunit 1 (MYPT1), the main regulatory subunit of MP in all smooth muscles, is a key convergence point of contractile and relaxatory pathways. Combinations of regulatory mechanisms, including isoform splicing, multiple phosphorylation sites, and scaffolding proteins, modulate MYPT1 activity with tissue and agonist specificities to affect contraction and relaxation. Other members of the PP1 family that do not target myosin, as well as PP2A and PP2B, dephosphorylate a range of proteins that affect smooth muscle contraction. This review discusses the role of phosphatases in smooth muscle contractility with a focus on MYPT1 in uterine smooth muscle. Myometrium shares characteristics of vascular and other visceral smooth muscles yet, during healthy pregnancy, undergoes hypertrophy, hyperplasia, quiescence, and labor as physiological processes. Myometrium presents an accessible model for the study of normal and pathological smooth muscle function, and a better understanding of myometrial physiology may allow the development of novel therapeutics for the many disorders of myometrial physiology from preterm labor to dysmenorrhea.