Safety and Efficacy of Tocolytics for the Treatment of Spontaneous Preterm Labour

Preventing Preterm Birth: Exploring Innovative Solutions

This review examines the complexities of preterm birth (PTB), emphasizes the pivotal role of inflammation in the pathogenesis of preterm labor, and assesses current available interventions. Antibiotics, progesterone analogs, mechanical approaches, nonsteroidal anti-inflammatory drugs, and nutritional supplementation demonstrate a limited efficacy. Tocolytic agents, targeting uterine activity and contractility, inadequately prevent PTB by neglecting to act on uteroplacental inflammation. Emerging therapies targeting toll-like receptors, chemokines, and interleukin receptors exhibit promise in mitigating inflammation and preventing PTB.

Methyl-CpG-binding protein 2 regulates CYP27A1-induced myometrial contraction during preterm labor

Persistent and intense uterine contraction is a risk factor for preterm labor. We previously found that methyl-CpG-binding protein 2 (MeCP2), as a target of infection-related microRNA miR-212-3p, may play an inhibitory role in regulating myometrium contraction. However, the molecular mechanisms by which MeCP2 regulates myometrial contraction are still unknown. In this study, we found that MeCP2 protein expression was lower in myometrial specimens obtained from preterm labor cases, compared to those obtained from term labor cases. Herein, using RNA sequence analysis of global gene expression in human uterine smooth muscle cells (HUSMCs) following siMeCP2, we show that MeCP2 silencing caused dysregulation of the cholesterol metabolism pathway. Notably, MeCP2 silencing resulted in the upregulation of CYP27A1, the key enzyme involved in regulating cholesterol homeostasis, in HUSMCs. Methylation-specific PCR, chromatin immunoprecipitation, and dual luciferase reporter gene technology indicated that MeCP2 could bind to the methylated CYP27A1 promoter region and repress its transcription. Administration of siCYP27A1 in a lipopolysaccharide (LPS)-induced preterm labor mouse model delayed the onset of preterm labor. Human preterm myometrium and the LPS-induced preterm labor mouse model both showed lower expression of MeCP2 and increased expression of CYP27A1. These results demonstrated that aberrant upregulation of CYP27A1 induced by MeCP2 silencing is one of the mechanisms facilitating inappropriate myometrial contraction. CYP27A1 could be exploited as a novel therapeutic target for preterm birth.

Comparison of terbutaline and atosiban as tocolytic agents in intrauterine repair of myelomeningocele: a retrospective cohort study

BACKGROUND

Myelomeningocele (MMC) is a neural tube defect disease. Antenatal repair of fetal MMC is an alternative to postnatal repair. Many agents can be used as tocolytics during the in utero fetal repair such as β2-agonists and oxytocin receptor antagonists, with possible maternal and fetal repercussions. This study aims to compare maternal arterial blood gas analysis between terbutaline or atosiban, as tocolytic agents, during intrauterine MMC repair.

METHODS

Retrospective cohort study. Patients were divided into two groups depending on the main tocolytic agent used during intrauterine MMC repair: atosiban (16) or terbutaline (9). Maternal arterial blood gas samples were analyzed on three moments: post induction (baseline, before the start of tocolysis), before extubation, and two hours after the end of the surgery.

RESULTS

Twenty-five patients were included and assessed. Before extubation, the terbutaline group showed lower arterial pH (7.347 ± 0.05 vs. 7.396 ± 0.02 for atosiban, p = 0.006) and higher arterial lactate (28.33 ± 12.76 mg.dL-1 vs. 13.06 ± 6.35 mg.dL-1, for atosiban, p = 0.001) levels.

CONCLUSIONS

Patients who received terbutaline had more acidosis and higher levels of lactate, compared to those who received atosiban, during intrauterine fetal MMC repair.

Effect of Calcium Channel Blocker on Labor Curve in Pregnant Individuals with Chronic Hypertension

OBJECTIVE

 This study aimed to compare the labor progress between individuals who received calcium channel blocker (CCB) and those who did not receive CCB during labor.

STUDY DESIGN

 This was a secondary analysis of a retrospective cohort study of individuals with chronic hypertension who underwent vaginal delivery at a tertiary care center from January 2010 to December 2020. We excluded individuals with prior uterine surgeries and a 5-minute Apgar score of less than 5. We used a repeated-measures regression with a third-order polynomial function to compare the average labor curves according to antihypertensive medication. Estimates of the median (5th-95th percentile) traverse times between two dilations were computed using interval-censored regression.

RESULTS

 Of 285 individuals with chronic hypertension, 88 (30.9%) received CCB. Individuals who received CCB during labor compared with those who did not were more likely to deliver at earlier gestational age and to have pregestational diabetes and superimposed preeclampsia (p  < 0.01). The progress of labor in the latent phase was not found to be significantly different between both groups (median: 11.51 vs. 8.74 hours; p = 0.08). However, after stratification by parity, nulliparous individuals who received CCB during labor were more likely to have a longer latent phase of labor (median: 14.4 vs. 8.5 hours; p  = 0.03) CONCLUSION:  A calcium channel blocker may slow the latent phase of labor in individuals with chronic hypertension. Aiming to minimize intrapartum iatrogenic interventions, allowing adequate time for pregnant individuals during the latent phase of labor is especially important if individuals are on a calcium channel blocker.

KEY POINTS

· Calcium channel blockers seem to be associated with a longer latent phase of labor.. · The effect of calcium channel blocker on labor was not observed in multiparous individuals.. · Allowing adequate labor time for individuals taking calcium channel blocker is important..

Stillbirth incidence and determinants in a tertiary health facility in the Volta Region of Ghana

BACKGROUND

Stillbirths are indicators of the quality of obstetrics care in health systems. Stillbirth rates and their associating factors vary by socio-economic and geographical settings. Published data on stillbirths and their associating factors in the Volta Region of Ghana are limited. This limits understanding of local factors that must be considered in designing appropriate interventions to mitigate the occurrence of stillbirths. This study determined the incidence of stillbirths and associated factors among deliveries at Ho Teaching Hospital (HTH) and contributes to understanding the consistent high stillbirths in the country and potentially in other low-resourced settings in sub-Saharan Africa.

METHOD

This was a prospective cohort study involving pregnant women admitted for delivery at HTH between October 2019 and March 2020. Data on socio-demographic characteristics such as age and employment, obstetric factors including gestational age at delivery and delivery outcomes like birthweight were collected using a pretested structured questionnaire. The primary outcome was the incidence of stillbirths at the facility. Summary statistics were reported as frequencies, percentages and means. Logistic regression methods were used to assess for association between stillbirths and independent variables including age and birthweight. Odds ratios were reported with 95% confidence intervals and associations with p-values < 0.05 were considered statistically significant.

RESULTS

A total of 687 women and their 702 newborns contributed data for analysis. The mean age (SD) was 29.3 (6.3) years and close to two-thirds had had at least one delivery previously. Overall stillbirth incidence was 31.3 per 1000 births. Of the 22 stillbirths, 17 were antepartum. Pre-eclampsia was the most common hypertensive disorder of pregnancy observed (49.3%, 33/67). Among others, less than 3 antenatal visits and low birthweight increased the odds of stillbirths in the bivariate analysis. In the final multivariate model, pregnancy and delivery at 28-34 weeks gestation [AOR 9.37(95% CI 1.18-74.53); p = 0.034] and induction of labour [AOR 11.06 (95% CI 3.10-39.42); p < 0.001] remained significantly associated with stillbirths.

CONCLUSION

Stillbirth incidence was 31.3 per 1000 births with more than half being antepartum stillbirths. Pregnancy/delivery at 28-34 weeks' gestation increased the odds of a stillbirth. Improving the quality of antenatal services, ensuring adherence to evidence-based protocols, accurate and prompt diagnosis and timely interventions of medical conditions in pregnancy particularly at 28-34 weeks' gestation could reduce incidence of stillbirths.

PGF2α induces a pro-labour phenotypical switch in human myometrial cells that can be inhibited with PGF2α receptor antagonists

Preterm birth is the leading cause of infant morbidity and mortality. There has been an interest in developing prostaglandin F2α (PGF2α) antagonists as a new treatment for preterm birth, although much of the rationale for their use is based on studies in rodents where PGF2α initiates labour by regressing the corpus luteum and reducing systemic progesterone concentrations. How PGF2α antagonism would act in humans who do not have a fall in systemic progesterone remains unclear. One possibility, in addition to an acute stimulation of contractions, is a direct alteration of the myometrial smooth muscle cell state towards a pro-labour phenotype. In this study, we developed an immortalised myometrial cell line, MYLA, derived from myometrial tissue obtained from a pregnant, non-labouring patient, as well as a novel class of PGF2α receptor (FP) antagonist. We verified the functionality of the cell line by stimulation with PGF2α, resulting in Gαq-specific coupling and Ca2+ release, which were inhibited by FP antagonism. Compared to four published FP receptor antagonists, the novel FP antagonist N582707 was the most potent compound [Fmax 7.67 ± 0.63 (IC50 21.26 nM), AUC 7.30 ± 0.32 (IC50 50.43 nM), and frequency of Ca2+ oscillations 7.66 ± 0.41 (IC50 22.15 nM)]. RNA-sequencing of the MYLA cell line at 1, 3, 6, 12, 24, and 48 h post PGF2α treatment revealed a transforming phenotype from a fibroblastic to smooth muscle mRNA profile. PGF2α treatment increased the expression of MYLK, CALD1, and CNN1 as well as the pro-labour genes OXTR, IL6, and IL11, which were inhibited by FP antagonism. Concomitant with the inhibition of a smooth muscle, pro-labour transition, FP antagonism increased the expression of the fibroblast marker genes DCN, FBLN1, and PDGFRA. Our findings suggest that in addition to the well-described acute contractile effect, PGF2α transforms myometrial smooth muscle cells from a myofibroblast to a smooth muscle, pro-labour-like state and that the novel compound N582707 has the potential for prophylactic use in preterm labour management beyond its use as an acute tocolytic drug.

Inhibitory effect and underlying mechanism of essential oil of Prangos ferulacea Lindl (L.) on spontaneous and induced uterine contractions in non-pregnant rats

Evidence suggests the use of natural compounds as support in the management of uterine contractility disorders. We recently demonstrated that the essential oil of Apiacea Prangos ferulacea (L.) (Prangoil) modulates intestinal smooth muscle contractility. Thus, we aimed to evaluate if Prangoil could also affect the contractility of uterine muscle in non-pregnant rat and to investigate the related action mechanism/s. The effects of the aromatic monoterpenes, β-ocimene and carvacrol, constituents of Prangoil, were also evaluated. Spontaneous contractions and contraction-induced by K+-depolarization and oxytocin in rat uterus were recorded in vitro, using organ bath technique. Prangoil reduced the amplitude of spontaneous contractions as well as responses to KCl and oxytocin. β-ocimene and carvacrol matched oil inhibitory effects. Prangoil effects were not affected by nitrergic and adenylyl cyclase inhibitors or non-specific potassium channel blocker, but they were reduced by nifedipine, L-type calcium channel inhibitor, or 2-aminoethoxydiphenylborate (2-APB), membrane-permeant inositol 1,4,5-triphosphate receptor inhibitor. The response to β-ocimene was reduced by nifedipine and by 2-APB (20 μM), whilst carvacrol inhibitory effect was attenuated only by nifedipine. In conclusion, Prangoil, and its components, β-ocimene and carvacrol, reduced spontaneous and KCl or oxytocin-induced contractions of rat myometrium, mainly modulating extracellular Ca2+ influx through L-Type channels and Ca2+ release from the intracellular store. Further studies could contribute to evaluate the potential use of Prangoil against disorders characterized by abnormal uterine contractions.

A multicenter, retrospective comparison of pregnancy outcomes between groups of preterm labor nulliparous mothers treated with atosiban vs. ritodrine in singleton and multiple pregnancies

OBJECTIVE

To evaluate the safety and efficacy of atosiban and ritodrine in pregnant women who were hospitalized for threatened preterm labor (TPL).

MATERIALS AND METHODS

Diagnosis records of preterm labor and subsequent pregnancy-related records and medical records of newborns were extracted from the Clinical Data Warehouse of the Catholic Medical Center's affiliated hospital. Since 2009, cases of preterm labor diagnosed before 34 weeks of pregnancy for first-time mothers who delivered at any one of three hospitals and who received drug treatment for more than 2 days to delay delivery were included in the dataset. Based on characteristics of Korea's national health insurance system, the drug treatment after diagnosis of preterm labor could be classified into cases using only ritodrine (571 women), cases using only atosiban (244 women), and cases where ritodrine treatment was started and then changed to atosiban (275 women). Demographic factors, obstetric outcomes, neonatal outcomes of the two groups were analyzed.

RESULTS

The duration and maintenance of pregnancy were found to be similar between the two groups, although the initial cervical length was significantly shorter in the atosiban cohort (AC). Only in multifetal pregnancies, the maintenance of pregnancy was significantly longer in the AC. The total duration of pregnancy did not show any significant difference between the two groups regardless of singleton or multiple pregnancy. However, the distribution graph showed non-responders in the ritodrine cohort (RC). Our study showed a difference in neonatal birth weight of singleton between the two groups. The length of hospitalization and the NICU admission rate were also significantly higher in the RC for singleton. Although not significant, the proportion of numbers with an Apgar score less than 7 was higher in the RC. Neonatal death was more common in the RG (8 cases in AC and 18 cases in RC).

CONCLUSIONS

Using atosiban for TPL is more effective than using ritodrine for maintaining pregnancy in the case of a multifetal pregnancy. In singleton pregnancies, neonatal outcomes of the atosiban group were superior to those of the ritodrine group. There seems to be a non-responder group when using ritodrine for TPL. Further studies are needed to determine causes of non-responders of ritodrine and effects of ritodrine on the fetus.

β3 Receptor Signaling in Pregnant Human Myometrium Suggests a Role for β3 Agonists as Tocolytics

Preterm labor leading to preterm birth is the leading cause of infant morbidity and mortality. At the present time, nothing can reliably halt labor once it begins. The knowledge that agonists of the β2 adrenergic receptor relax airway smooth muscle and are effective in the treatment of asthma led to the notion that β2 mimetics would prevent preterm birth by relaxing uterine smooth muscle. The activation of cAMP-dependent protein kinase by β2 receptors is unable to provide meaningful tocolysis. The failure of β2 agonists such as ritodrine and terbutaline to prevent preterm birth suggests that the regulation of uterine smooth muscle is disparate from that of airway. Other smooth muscle quiescent-mediating molecules, such as nitric oxide, relax vascular smooth muscle in a cGMP-protein kinase G-dependent manner; however, nitric oxide activation of protein kinase G fails to explain the relaxation of the myometrium to nitric oxide. Moreover, nitric oxide-mediated relaxation is blunted in preterm labor, and thus, for this reason and because of the fall in maternal blood pressure, nitric oxide cannot be employed as a tocolytic. The β3 adrenergic receptor-mediated relaxation of the human myometrium is claimed to be cAMP-dependent protein kinase-dependent. This is scientifically displeasing given the failure of β2 agonists as tocolytics and suggests a non-canonical signaling role for β3AR in myometrium. The addition of the β3 agonist mirabegron to pregnant human myometrial strips in the tissue bath relaxes oxytocin-induced contractions. Mirabegron stimulates nitric oxide production in myometrial microvascular endothelial cells, and the relaxation of uterine tissue in vitro is partially blocked by the addition of the endothelial nitric oxide synthase blocker Nω-Nitro-L-arginine. Recent data suggest that both endothelial and smooth muscle cells respond to β3 stimulation and contribute to relaxation through disparate signaling pathways. The repurposing of approved medications such as mirabegron (Mybetriq™) tested in human myometrium as uterine tocolytics can advance the prevention of preterm birth.

Increased Survival Concomitant with Unchanged Morbidity and Cognitive Disability among Infants Born at the Limit of Viability before 24 Gestational Weeks in 2009-2019

INTRODUCTION

The aim was to determine risk factors among mothers and outcomes for their children born at the limit of viability in 2009-2019, before and after the introduction of extended interventionist guidelines.

METHODS

A retrospective cohort study of births at 22 + 0-23 + 6 gestational weeks in a Swedish Region in 2009-2015 (n = 119), as compared to 2016-2019 (n = 86) after the introduction of new national interventionist guidelines. Infant mortality, morbidity, and cognitive functions at 2 years corrected age according to the Bayley-III Screening Test were monitored.

RESULTS

Maternal risk factors for extreme preterm birth were identified. The intrauterine fetal death rates were comparable. Among births at 22 weeks, the neonatal mortality tended to decrease (96 vs. 76% of live births (p = 0.05)), and the 2-year survival tended to increase (4 vs. 24% (p = 0.05)). Among births at 23 weeks, the neonatal mortality decreased (56 vs. 27% of live births (p = 0.01)), and the 2-year survival increased (42 vs. 64% (p = 0.03)). Somatic morbidity and cognitive disability at 2 years corrected age were unchanged.

CONCLUSION

We identified maternal risk factors that emphasize the need for standardized follow-up and counseling for women at increased risk of preterm birth at the limit of viability. The increased infant survival concomitant with unchanged morbidity and cognitive disability highlight the importance of ethical considerations regarding interventionist approaches at threatening preterm birth before 24 weeks.

Efficacy of atosiban for repeated implantation failure in frozen embryo transfer cycles

Atosiban was commonly added to improve pregnancy outcomes of patients with repeated embryo implantation failure (RIF). In this study, we aimed to investigate the effect of atosiban before transferring the frozen-thawed embryo to RIF patients. This retrospective study was conducted in the Hospital for Reproductive Medicine affiliated to Shandong University from August 2017 to June 2021. A total of 1774 women with a history of RIF undergoing frozen embryo transfer (FET) were included in this study. All the participants were classified into atosiban or control group: Group A included 677 patients who were administered atosiban intravenously 30 min prior to FET with a dose of 37.5 mg; Group B included 1097 patients who received no atosiban before the transfer. There were no significant differences observed in the live birth rate (LBR) (39.73% vs. 39.02%, P = 0.928) between the two groups. Other secondary outcomes including biochemical pregnancy rate, clinical pregnancy rate, implantation rate, clinical miscarriage rate and preterm birth rate were similar between the two groups (all P > 0.05). However, subgroup analysis demonstrated significantly higher preterm birth rates in the control group compared with the atosiban group (0 versus 3.0%, P = 0.024) in the natural FET cycles. Atosiban may not improve pregnancy outcomes of RIF patients in FET cycles. However, the effects of Atosiban on pregnancy outcomes should be assessed in clinical trials with larger sample sizes.

Atosiban-induced acute pulmonary edema: A rare but severe complication of tocolysis

Background

Atosiban is commonly used to delay premature labor in pregnant women and is thought to have few side effects.

Objectives

To report a case of acute pulmonary edema (APE) following administration of atosiban and conduct a systematic review to identify common characteristics and risk factors of atosiban-associated APE.

Methods

Searches were performed in Pubmed, Embase, and Web of Science using the keyword "Atosiban" combined with the terms "Pulmonary edema" or "Dyspnea" or "Hypoxia" on 9th July 2022. Only case reports of atosiban-associated APE were included without language restrictions. Data were extracted from the reports, and median, range, and percentages were calculated as applicable. The risk of bias was assessed using the Joanna Briggs Institute critical appraisal checklist for case reports.

Results

Seven cases of atosiban-associated APE were included in the systematic review, including our case. APE occurred at a median gestational age of 32 + 6 weeks. Most patients were nulliparous (6/7, 85.7%) and were in multiple pregnancies (5/7, 71.4%). All patients were prescribed antenatal corticosteroids and tocolytics, with three (42.9%) receiving only atosiban and four (57.1%) receiving atosiban and other tocolytics. The median interval from starting atosiban administration to APE onset was about 40 h, and three patients (42.9%) showed symptoms 2-10 h after the end of atosiban treatment. Radiographic examinations (chest X-ray and/or computer tomography scan) confirmed APE in all patients and pleural effusion in four patients (57.1%). Five patients (71.4%) underwent emergency cesarean section, one patient (14.3%) with twin pregnancy had vaginal delivery with the help of suction cup and forceps, and another patient (14.3%) continued the pregnancy. All patients recovered well after administration of oxygen, diuresis, and other supportive therapy.

Conclusion

Atosiban may cause acute pulmonary edema in patients with underlying risk factors. This complication remains rare, but caution during tocolytic treatment using atosiban is recommended.

Combined uterorelaxant effect of magnesium sulfate and terbutaline: Studies on late pregnant rat uteri in vitro and in vivo

INTRODUCTION

Preterm delivery and its complications are among the biggest challenges and health risks in obstetrical practice. Several tocolytic agents are used in clinical practice, although the efficacy and side effect profiles of these drugs are not satisfying. The aim of this study was to investigate the uterus relaxant effect of the coadministration of β2 -mimetic terbutaline and magnesium sulfate (MgSO4 ) in an isolated organ bath and to perform in vivo smooth muscle electromyographic (SMEMG) studies in pregnant rats. In addition, we also investigated whether the tachycardia-inducing effect of terbutaline can be reduced by the presence of magnesium, due to the opposite heart rate modifying effects of the two agents.

MATERIAL AND METHODS

In the isolated organ bath studies, rhythmic contractions of 22-day- pregnant Sprague-Dawley rats were stimulated with KCl, and cumulative dose-response curves were constructed in the presence of MgSO4 or terbutaline. The uterus-relaxing effects of terbutaline were also investigated in the presence of MgSO4 in both normal buffer and Ca2+ -poor buffer. The in vivo SMEMG studies were carried out under anesthesia with the subcutaneous implantation of an electrode pair. The animals were treated with MgSO4 or terbutaline alone or in combination in a cumulative bolus injection. The implanted electrode pair also detected the heart rate.

RESULTS

Both MgSO4 and terbutaline reduced uterine contractions in vitro and in vivo, furthermore, the administration of a small dose of MgSO4 significantly enhanced the relaxant effect of terbutaline, especially in the lower range. However, in Ca2+ -poor environment, MgSO4 was not able to increase the effect of terbutaline, indicating the role of MgSO4 as a Ca2+ channel blocker. In the cardiovascular studies, MgSO4 significantly decreased the tachycardia-inducing effect of terbutaline in late pregnant rats.

CONCLUSIONS

The combined application of MgSO4 and terbutaline may have clinical significance in tocolysis, which must be confirmed in clinical trials. Furthermore, MgSO4 could substantially reduce the tachycardia-inducing side effect of terbutaline.

Functional rewiring of G protein-coupled receptor signaling in human labor

Current strategies to manage preterm labor center around inhibition of uterine myometrial contractions, yet do not improve neonatal outcomes as they do not address activation of inflammation. Here, we identify that during human labor, activated oxytocin receptor (OTR) reprograms the prostaglandin E2 receptor, EP2, in the pregnant myometrium to suppress relaxatory/Gαs-cAMP signaling and promote pro-labor/inflammatory responses via altered coupling of EP2 from Gαq/11 to Gαi/o. The ability of EP2 to signal via Gαi/o is recapitulated with in vitro OT and only following OTR activation, suggesting direct EP2-OTR crosstalk. Super-resolution imaging with computational modeling reveals OT-dependent reorganization of EP2-OTR complexes to favor conformations for Gαi over Gαs activation. A selective EP2 ligand, PGN9856i, activates the relaxatory/Gαs-cAMP pathway but not the pro-labor/inflammatory responses in term-pregnant myometrium, even following OT. Our study reveals a mechanism, and provides a potential therapeutic solution, whereby EP2-OTR functional associations could be exploited to delay preterm labor.

•

EP2 activity is reprogrammed toward pro-inflammatory pathways during human labor

•

Oxytocin downregulates EP2-Gαs signaling and switches EP2-Gαq/11 signaling to Gαi/o

•

EP2/OTR heterotetramers are reorganized by oxytocin to conformations favoring Gαi

•

EP2 agonist PGN9856i does not activate pro-labor signals even after oxytocin treatment

Chinese Herbal Medicines Have Potentially Beneficial Effects on the Perinatal Outcomes of Pregnant Women

Introduction: Tocolytic treatment is beneficial to pregnant women with a risk of premature labor or miscarriage. However, previous reports have shown that progestogen might not be effective and ritodrine may increase the risk of maternal vascular-related diseases. Chinese herbal products (CHP) are used as alternative therapies for pregnant women. The goal was to evaluate the efficacy of combined tocolytic therapy and CHP therapy in pregnancy outcomes for pregnant women in Taiwan.

Materials and Methods: We conducted a retrospective cohort study based on the National Health Insurance Research Database. A total of 47,153 pregnant women treated with tocolytics aged 18–50 years from 2001 to 2015 were selected from two million random samples. According to the medical use of tocolytics and CHP, we divided the users into two groups: western medicine (WM) only (n = 40,961) and WM/CHP (n = 6,192) groups. A propensity score (PS)-matched cohort (6,192 pairs) was established based on baseline confounders. All participants were followed up to perinatal outcomes. Conditional logistic regression analysis was used to examine the effects of CHP use on the odds of miscarriage and preterm birth.

Results: The adjusted odds ratio (OR) for premature birth in the WM/CHP group (n = 411, 6.64%) was significantly lower than in the WM group (n = 471, 7,61%) (0,86, 95% confidence interval [CI], 0.74–0.99). Further subgroup analysis based on the usage of formulae that activate blood and remove stasis or purgative formulae, the adjusted OR of preterm birth of those using these formulae was significantly lower in the WM/CHP group (n = 215, 6.32%) than that in the WM group (n = 265, 7.77%) (OR: 0.79, 95% CI: 0.65–0.96).

Conclusion: We found that the combination of CHP and tocolytics can be beneficial to pregnant women in the prevention of premature birth. Further research is required to investigate causal relationships.

Progesterone Gel and Placebo Prolonged Pregnancy More Effectively Than Intravenous Tocolysis Alone in Women with Preterm Labor

The aim of this trial was to evaluate the effect of progesterone gel compared to placebo in prolonging pregnancy among women with preterm labor. Methods: A randomized controlled trial in Sweden in 2009−18. Women with early preterm labor were randomized to daily doses of progesterone gel 90 mg (n = 28) or placebo (n = 30) after standard intravenous tocolytics. Women with intravenous tocolytics alone (n = 29) served as controls. Results: The median latency to delivery was 68 (range 28−88) days with progesterone and 72 (range 9−90) days with placebo (p = 0.84), compared to 1 (range 1−2) day in the control group (progesterone and placebo vs. control p < 0.001). The rate of preterm birth before 34 weeks was 32% after progesterone and 37 % after placebo (p = 0.32) compared to 100 % in the control group (p < 0.001, respectively). The composite neonatal morbidity (p = 0.65) and neonatal intensive care unit admission (p = 0.12) were comparable between the progesterone and placebo groups and lower in these groups compared with neonates in the control group (p < 0.001, respectively). Conclusions: Progesterone gel and placebo were equally effective in prolonging pregnancy among women with early preterm labor, and both treatments were more effective than standard intravenous tocolysis alone. We hypothesize that the acidic placebo gel reinforced the biochemical barrier at the uterine cervix, which counteracts ascending pathogen invasion and subsequent inflammation, and thereby prevented preterm labor.

The risk of preterm birth in women with history of short cervix delivering at term in the previous pregnancy: a retrospective cohort study

PURPOSE

To investigate whether women with a short cervical length (CL), but delivered at term in the first pregnancy might have increased risks of having short cervix and spontaneous preterm birth (sPTB) in the subsequent pregnancies.

METHODS

This is a retrospective cohort study including singleton gestations who were delivered between Jan 2011 and Dec 2018, who had had one childbirth experience and who had transvaginal sonographic CL assessment performed at mid-trimester (18 ~ 30 weeks) in both pregnancy. The women were divided into four group according to the history of preterm birth and a short cervix (< 25 mm before 30 weeks of gestation): (1) the Preterm-short cervix group, (2) the Preterm-no shortening group, (3) the Term-short cervix group, and (4) the Term-no shortening group. We compared the risk of having short cervix and sPTB during the second pregnancy of women. Secondary outcomes were threatened preterm labor, need for tocolytics, and cerclage placement.

RESULTS

A total of 804 women met our inclusion criteria. The rate of having short cervix (< 25 mm before 28 weeks of gestation) during the second pregnancy in women in the Term-short cervix group (43.2%) was significantly higher than those in women in the Term-no shortening group (6.6%), and in the Preterm-no shortening group (8.8%) (all p < 0.001 with Bonferroni correction), but not higher than those in women with the Preterm-short cervix group (30.8%, p > 0.05 with Bonferroni correction). When compared with women in the Preterm-no shortening group, women in the Term-short cervix group were also at an increased risk of need for need of tocolytics (60.2% vs. 26.5%) and cerclage placement (15.9% vs. 6.1%, all p < 0.001). Women in the Term-short cervix group had an increased risk of sPTB (< 37 weeks) during the second pregnancy, as compared to those in the Term-no shortening group (adjusted odds ratio 5.098, 95% CI 2.107-11.874).

CONCLUSION

Women with a history of short cervix in their first pregnancy, but who delivered at term, were at increased risk of having a short cervix and sPTB in their second pregnancy, as compared to women with a history of term delivery without cervical shortening. Thus, short cervix of the previous pregnancy might be a predictive factors for preterm birth in the subsequent pregnancy.

Next generation strategies for preventing preterm birth

Preterm birth (PTB) is defined as delivery before 37 weeks of gestation. Globally, 15 million infants are born prematurely, putting these children at an increased risk of mortality and lifelong health challenges. Currently in the U.S., there is only one FDA approved therapy for the prevention of preterm birth. Makena is an intramuscular progestin injection given to women who have experienced a premature delivery in the past. Recently, however, Makena failed a confirmatory trial, resulting the Center for Drug Evaluation and Research's (CDER) recommendation for the FDA to withdrawal Makena's approval. This recommendation would leave clinicians with no therapeutic options for preventing PTB. Here, we outline recent interdisciplinary efforts involving physicians, pharmacologists, biologists, chemists, and engineers to understand risk factors associated with PTB, to define mechanisms that contribute to PTB, and to develop next generation therapies for preventing PTB. These advances have the potential to better identify women at risk for PTB, prevent the onset of premature labor, and, ultimately, save infant lives.

Short-Term Outcomes of Atosiban in the Treatment of Preterm Labour at the Sultan Qaboos University Hospital, Muscat, Oman: A tertiary care experience

Objectives

This study aimed to generate baseline evidence regarding the effectiveness of atosiban in delaying delivery by ≥48 hours among pregnant women presenting with threatened preterm labour (TPL). The secondary objective was to assess the relationship between atosiban success and various perinatal factors and neonatal outcomes.

Methods

This retrospective study was conducted between June 2008 and May 2018 at the Sultan Qaboos University Hospital, Muscat, Oman. The medical records of all pregnant women who received atosiban between 24–34 gestational weeks for TPL during this period were reviewed.

Results

A total of 159 women were included in the study. Atosiban was successful in delaying delivery by ≥48 hours in 130 cases (81.8%). Approximately half of the women (50.9%) achieved uterine quiescence in <12 hours. Failure to delay delivery by ≥48 hours was significantly lower among women with normal versus abnormal cervical findings (11.1% versus 25.6%; P = 0.023). Only 9.4% of women experienced minor side-effects. Mean birth weight (2,724.55 versus 1,707.59 g; P <0.001) and Apgar scores at 5 minutes (9.66 versus 8.28; P <0.001) were significantly higher among neonates delivered at ≥48 versus <48 hours post-atosiban, whereas the rate of neonatal respiratory distress syndrome was significantly lower (18.4% versus 81.6%; P <0.001).

Conclusion

Atosiban was highly effective in delaying delivery by ≥48 hours and resulted in few adverse maternal side-effects and neonatal outcomes. To the best of the authors’ knowledge, this is the first study conducted in Oman to evaluate the effectiveness of atosiban in preventing preterm labour.

Tocolytic effect of the monoterpenic phenol isomer, carvacrol, on the pregnant rat uterus

Despite the wide application of carvacrol (CAR) in different biological and medical areas, there is still insufficient electrophysiological data on the mechanisms of action of CAR, particularly in the pregnant uterine function. The aim of this study was to evaluate the in vitro tocolytic effect of CAR on the contractility of isolated pregnant rat uterus in the presence of a calcium channel antagonist (nifedipine) and a cyclooxygenase inhibitor (indomethacin). The uteri were isolated from pregnant Wistar rats at 16-18 days of pregnancy and suspended in an isolated organ bath chamber containing a Ringer's physiological solution and aerated with 95% O₂and 5% CO₂. Samples were used in functional tests to evaluate the inhibitory effect of CAR at increasing concentrations on the rhythmic spontaneous, oxytocin-induced phasic, K⁺-induced tonic, and Ca²⁺-induced contractions. The differences in inhibitory concentration-50 and E_maxamong the compounds were determined using the one-way ANOVA followed by a post hoc Student-Newman-Keuls or Bonferroni test, in all casesP < 0.05 was considered statistically significant. Nifedipine was used as positive controls where required. CAR caused a significant concentration-dependent inhibition of the uterine contractions induced by the pharmaco- and electro-mechanic stimuli. We showed that the inhibitory effects of CAR depends on the type of muscle contraction stimuli, and that it acts stronger in spontaneous rhythmic activity and in contractions of isolated rat uterus induced by Ca²⁺. Nifedipine was more potent than CAR and indomethacin on the uterine contractility (P < 0.05), but none of them was more effective than nifedipine. Therefore, the tocolytic effect induced by CAR was associated with the blockade of the calcium channels in the pregnant rat uterus. This property placed CAR as a potentially safe and effective adjuvant agent in cases of preterm labor, an area of pharmacological treatment that requires urgent improvement.

Prevention of preterm birth: Proactive and reactive clinical practice-are we on the right track?

Preterm birth remains the major cause of death and disability among children under the age of five. In developing countries antenatal preterm birth prevention clinics are set up to provide cervical length surveillance and/or treatment modalities such as cerclage or progesterone for those women with identified risk factors such as previous cervical treatment or preterm birth. However, 85% of women have no risk factors for PTB and currently there is no biomarker to screen women early in pregnancy. Women will present unexpectedly in threatened preterm labour and we have no choice but to adopt a re-active approach to their care by using predication and preparation strategies such as fetal fibronectin, tocolytic therapy and steroids. Despite these strategies approximately 15-20% of these women will give birth preterm before 34 weeks. There is a urgent need to re-design primary, secondary and tertiary prevention strategies for spontaneous preterm labour (sPTL) in singleton pregnancies aimed at identifying and addressing key gaps in clinical practice and research.

Functionally Selective Inhibition of the Oxytocin Receptor by Retosiban in Human Myometrial Smooth Muscle

Novel small molecule inhibitors of the oxytocin receptor (OTR) may have distinct pharmacology and mode of action when compared with first-generation oxytocin antagonists when used for the prevention of preterm birth. The aim was to determine the mechanism of action of small molecule OTR antagonists retosiban and epelsiban compared with the currently used peptide-based compound atosiban. Human myometrial samples were obtained at cesarean section and subjected to pharmacological manipulations to establish the effect of antagonist binding to OTR on downstream signaling. Retosiban antagonism of oxytocin action in human myometrium was potent, rapid, and reversible. Inhibition of inositol 1,4,5-trisphosphate (IP3) production followed single-site competitive binding kinetics for epelsiban, retosiban, and atosiban. Retosiban inhibited basal production of IP3 in the absence of oxytocin. Oxytocin and atosiban but not retosiban inhibited forskolin, and calcitonin stimulated 3',5'-cyclic adenosine 5'-mono-phosphate (cAMP) production. Inhibition of cAMP was reversed by pertussis toxin. Oxytocin and atosiban, but not retosiban and epelsiban, stimulated extracellular regulated kinase (ERK)1/2 activity in a time- and concentration-dependent manner. Oxytocin and atosiban stimulated cyclo-oxygenase 2 activity and subsequent production of prostaglandin E2 and F2α. Prostaglandin production was inhibited by rofecoxib, pertussin toxin, and ERK inhibitor U0126. Oxytocin but not retosiban or atosiban stimulated coupling of the OTR to Gα q G-proteins. Oxytocin and atosiban but not retosiban stimulated coupling of the OTR to Gα i G-proteins. Retosiban and epelsiban demonstrate distinct pharmacology when compared with atosiban in human myometrial smooth muscle. Atosiban displays agonist activity at micromolar concentrations leading to stimulation of prostaglandin production.