New medicines for spontaneous preterm birth prevention and preterm labour management: landscape analysis of the medicine development pipeline

Evaluation of a two-tier preterm birth prevention service in a tertiary hospital in the United Kingdom: a retrospective cohort study

BACKGROUND

Preterm birth is the most important cause of neonatal morbidity and mortality. Clinical guidelines recommend assessment of risk of preterm birth and implementation of interventions to reduce preterm birth risk through dedicated preterm birth clinics. We hypothesized that a two-tier preterm birth clinic pathway can safely manage women at the highest risk of preterm birth while reducing intervention for women at moderate risk of preterm birth. We aimed to test this hypothesis by evaluating risk factors, management, and outcomes of women attending a two-tier preterm birth prevention service.

METHODS

We conducted a retrospective cohort study of women who gave birth between January and June 2021 at a tertiary hospital in Oxford, UK. We included two cohorts: women attending a Cervical Screening Clinic and women attending a Preterm Birth Clinic, and we also reviewed all cases of births before 34 weeks over that time period. At the initial midwife appointment at 8-10 weeks' gestation, risk factors for preterm birth were assessed. Pregnant women with moderate risk factors (previous preterm birth at 32+ 0 - 33+ 6 weeks, previous preterm prelabour rupture of membranes (PPROM) at 32+ 0 - 33+ 6 weeks, previous LLETZ / cone biopsy, known abnormal uterus, previous caesarean section at 10 cm dilatation, and multiple pregnancy) were referred to the Cervical Screening Clinic for a cervical length scan by a sonographer. Pregnant women with major risk factors (previous preterm birth at 16+ 0 - 31+ 6 weeks, previous PPROM at less than 32+ 0 weeks, radical trachelectomy, previous cervical cerclage) as well as those with a cervix < 25 mm at any scan were referred to the Preterm Birth Clinic for a cervical length scan and counselling by a specialist obstetrician. Detailed information on risk factors, management, and perinatal outcomes were collected from case notes and analysed.

RESULTS

189 women attended the Cervical Screening Clinic: 79.1% had a moderate risk factor for preterm birth, 100% had a cervical length scan, 7% had a short cervix and 4.2% received an intervention. All 196 infants were live born, with overall preterm birth rates of 14.8% at < 37 weeks, 3.1% at < 32 weeks, and 0% at < 28 weeks. The spontaneous live preterm birth rates were 9.7% at < 37 weeks, 2.6% at < 32 weeks and 0% at < 28 weeks. 79 women attended the Preterm Birth Clinic: 87.3% had a major risk factor for preterm birth, 100% had ≥ 1 cervical length scan, 41.3% had a short cervix, 78.1% received vaginal progesterone, and 39% had a cervical cerclage. Overall preterm birth rates were 33.8% at < 37 weeks, 10.3% at < 32 weeks and 4.4% at < 28 weeks. Spontaneous live preterm birth rates were 22.1% at < 37 weeks, 7.4% at < 32 weeks, and 2.9% at < 28 weeks. 115 women gave birth to 130 babies before 34 weeks: 80% had no major risk factor for preterm birth, 29% had a cervical length scan and less than 15% had an intervention. Over 90% had a live birth, but the neonatal death rate was high (8.5%).

CONCLUSION

Women with moderate risk factors for preterm birth seen in the Cervical Screening Clinic had low rates of intervention and good perinatal outcomes. Most women with major risk factors were appropriately referred and managed by the Preterm Birth Clinic. This two-tier preterm birth prevention service therefore appears safe and effective.

N,N-dimethylacetamide blocks inflammation-induced preterm birth and remediates maternal systemic immune responses

The common excipient, N,N-dimethylacetamide (DMA), prevents imminent endotoxin-induced preterm birth in mice. The present study hypothesized that DMA forestalls preterm birth to term (defined as day 18.5 or later) by attenuating bacterial endotoxin lipopolysaccharide (LPS)-induced maternal systemic inflammatory responses and cervix remodeling. Accordingly, LPS (i.p.) on day 15 postbreeding stimulated preterm delivery within 24 h while mice treated with DMA 2 h preceding and 9 h following LPS administration remained pregnant, comparable to saline and DMA controls, to deliver viable pups at term. Irrespective of LPS or DMA + LPS treatment, maternal plasma pro- and anti-inflammatory cytokines on day 15.5 (12 h post-LPS) increased tenfold compared to baseline concentrations in controls. On day 16 of pregnancy, plasma concentrations of G-CSF and TNFα were statistically significantly reduced in the prepartum LPS + DMA group compared to those in postpartum mice given LPS. By day 18 of pregnancy, all cytokines returned to baseline-equivalent to low systemic levels throughout the study in saline and DMA controls that gave birth at term. In addition, maternal plasma progesterone declined within 12 h in prepartum LPS-treated mice to postpartum concentrations on day 16. Although a similar transient decrease occurred by 12 h in DMA + LPS mice, plasma progesterone returned to baseline concentrations in controls. Contemporaneously, the progression of prepartum cervix remodeling leading to preterm delivery was acutely forestalled by DMA without impeding birth at term. These findings support the hypothesis that DMA not only prevents inflammation-driven preterm birth, but rescues pregnancy for birth to occur at term. The results raise the possibility that maternal signals can forecast risk of preterm birth while selective suppression of systemic inflammation can mitigate adverse pregnancy outcomes.

Bryophyllum pinnatum modulation of signaling pathways relevant for preterm labor in human myometrial cells

Preparations of Bryophyllum pinnatum have been used as a well-tolerated treatment of preterm labor, initially in anthroposophic hospitals and, more recently, also in conventional settings. In vitro studies with human myometrial cells have shown that B. pinnatum leaf press juice inhibits both intracellular Ca2 + signaling and the activation of inflammatory pathways induced by the relevant hormone oxytocin. However, the compounds responsible for these inhibitory effects and the potential involvement of related signaling pathways remain unknown. In the present study, we aim to address these knowledge gaps. In vitro experiments were conducted in hTERT-C3 human myometrial cells, using alamarBlue assay, fluorescent intracellular Ca2+ assay, ELISA, proteomics and real-time PCR. Contractility studies were conducted in an ex vivo organ bath model using human myometrial tissue. No single compound from B. pinnatum leaves mimicked the inhibitory effect of the whole leaf press juice on OT-induced Ca2+ signaling. However, a bufadienolide-enriched fraction and the bufadienolides bersaldegenin-1,3,5-acetate, bryophyllin A and bersaldegenin-3-acetate, but not bersaldegenin-1-acetate, reduced OT-induced COX-2 expression and attenuated NFκB activation. That the juice can inhibit prostaglandin F2α-induced contractions was shown in the myometrium bath model. Proteomics analysis revealed that the leaf juice reduced expression of various extracellular matrix proteins. Cell viability assays showed that the various inhibitory effects cannot be attributed to cytotoxicity. Taken together, these results further support investigations on the use of B. pinnatum as a well-tolerated candidate for long-term treatment of preterm labor.

N,N-dimethylacetamide blocks inflammation-induced preterm birth and remediates maternal systemic immune responses

The common excipient, N,N-dimethylacetamide (DMA), prevents imminent endotoxin-induced preterm birth in mice. The present study hypothesized that DMA forestalls preterm birth to term (defined as day 18.5 or later) by attenuating bacterial endotoxin lipopolysaccharide (LPS)-induced maternal systemic inflammatory responses and cervix remodeling. Accordingly, LPS (i.p.) on day 15 postbreeding stimulated preterm delivery within 24 h while mice treated with DMA 2 h preceding and 9 h following LPS administration remained pregnant, comparable to saline and DMA controls, to deliver viable pups at term. Irrespective of LPS or DMA+LPS treatment, maternal plasma pro- and anti-inflammatory cytokines on day 15.5 (12 h post-LPS) increased 10-fold compared to baseline concentrations in controls. On day 16 of pregnancy, plasma concentrations of G-CSF and TNFα were reduced in the prepartum LPS+DMA group compared to those in postpartum mice given LPS. By day 18 of pregnancy, all cytokines returned to baseline - equivalent to low systemic levels throughout the study in saline and DMA controls that gave birth at term. In addition, maternal plasma progesterone declined within 12 h in prepartum LPS-treated mice to postpartum concentrations on day 16. Although a similar transient decrease occurred by 12 h in DMA+LPS mice, plasma progesterone returned to baseline concentrations in controls. Contemporaneously, the progression of prepartum cervix remodeling leading to preterm delivery was acutely forestalled by DMA without impeding birth at term. These findings support the hypothesis that DMA not only prevents inflammation-driven preterm birth, but rescues pregnancy for birth to occur at term. The results raise the possibility that maternal signals can forecast risk of preterm birth while selective suppression of systemic inflammation can mitigate adverse pregnancy outcomes.

Cooperation of aquaporin 5 and the adrenergic system in the initiation of birth in rat model

Aquaporins (AQPs) are involved in the process of implantation, regulate myometrial contractions and cervical ripening, and maintain appropriate placental functioning. The molecular mechanism of these functions is not fully understood. Our study aimed to investigate the physiological significance of AQP5 during pregnancy and to determine the cooperation between the adrenergic system and the AQP5 in uterine contraction in the late-pregnant rat uterus. After administering AQP5 siRNA intraperitoneally to Sprague-Dawley rats, the length of the gestational period was determined and the changes in uterine contractions were measured in an isolated organ bath system. Pharmacological influence on AQP5 expression and uterine contraction was investigated by treatment with terbutaline (10 mg/kg, subcutaneously) and doxazosin (5 mg/kg, orally) in vivo; and mercuric chloride (HgCl2), in vitro. Moreover, the levels of cAMP response element binding protein (CREB) were measured in the uterus by an ELISA kit. The gestational period became shorter, AQP5 expression significantly decreased and rat uterus contraction increased after AQP5 siRNA treatment compared to the control. Treatment with terbutaline significantly increased AQP5 mRNA and protein expression after 30 min and continuously reduced it until 90 min, whereas doxazosin treatment did not significantly alter AQP5 expression. Treatment with the AQP5 antagonist HgCl2 increased spontaneous uterus contraction and decreased norepinephrine-induced uterus contraction with decreasing AQP5 expression in pregnant rat uterus. Moreover, the tocolytic effect through the adrenergic system was amplified in the presence of an AQP5 antagonist, presumably via the changes in cAMP level. In conclusion, our findings elucidate the collaborative role of aquaporin 5 (AQP5) and adrenergic systems in the regulation of uterine contractions in late-pregnant rats. Our findings suggest this may be a good starting point for developing a new tocolytic therapy.

The drug drought in maternal health: an ongoing predicament

We developed a comprehensive database of medicines that are used or are being investigated for pre-eclampsia or eclampsia, preterm birth or labour, postpartum haemorrhage, intrauterine growth restriction, and fetal distress and that were in active development between 2000 and 2021. A total of 444 candidates were identified: approximately half of candidates were in active development, two-thirds had been repurposed after initially being used for another condition, and just under half were in preclinical studies. Only 64 candidates were in active late-stage (phase 3) development as of Oct 25, 2021, and given the slow pace of biomedical development, it could take years before any of these products eventually make it to market. A lack of innovation for maternal health medicines persists, and the market continues to fail pregnant individuals. There is a need for collective action from all relevant stakeholders to accelerate investment in the development of new or improved medicines for pregnancy-related conditions.

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.

A historical narrative review through the field of tocolysis in threatened preterm birth

Preterm birth presents a significant challenge in clinical obstetrics, requiring effective strategies to reduce associated mortality and morbidity risks. Tocolytic drugs, aimed at inhibiting uterine contractions, are a key aspect of addressing this challenge. Despite extensive research over many years, determining the most effective tocolytic agents remains a complex task, prompting better understanding of the underlying mechanisms of spontaneous preterm birth and recording meaningful outcome measures. This paper provides a comprehensive review of various obsolete and current tocolytic drug regimens that were instituted over the past century, examining both historical contexts and contemporary challenges in their development and adoption. The examination of historical debates and advancements highlights the complexity of introducing new therapies. While the search for effective tocolytics continues, questions arise regarding their actual benefits in obstetric care and the necessity for ongoing exploration. The presence of methodological limitations in current research emphasizes the importance of well-designed randomized controlled trials with robust endpoints and extended follow-up periods.In response to these complexities, the consideration of shifting towards prevention strategies aimed at addressing the root causes of preterm labor becomes more and more evident. This potential shift may offer a more effective approach than relying solely on tocolytics to delay labor initiation.Ultimately, effectively managing threatened preterm birth necessitates ongoing investigation, innovation, and a willingness to reassess strategies in pursuit of optimal outcomes for mothers, neonates, and long-term child health.