Effect of nifedipine and atosiban on perinatal brain injury: secondary analysis of the APOSTEL-III trial

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.

Treatment of preterm brain injury via gut-microbiota-metabolite-brain axis

BACKGROUND

Brain injury in preterm infants potentially disrupts critical structural and functional connective networks in the brain. It is a major cause of neurological sequelae and developmental deficits in preterm infants. Interesting findings suggest that the gut microbiota (GM) and their metabolites contribute to the programming of the central nervous system (CNS) during developmental stages and may exert structural and functional effects throughout the lifespan.

AIM

To summarize the existing knowledge of the potential mechanisms related to immune, endocrine, neural, and blood-brain barrier (BBB) mediated by GM and its metabolites in neural development and function.

METHODS

We review the recent literature and included 150 articles to summarize the mechanisms through which GM and their metabolites work on the nervous system. Potential health benefits and challenges of relevant treatments are also discussed.

RESULTS

This review discusses the direct and indirect ways through which the GM may act on the nervous system. Treatment of preterm brain injury with GM or related derivatives, including probiotics, prebiotics, synbiotics, dietary interventions, and fecal transplants are also included.

CONCLUSION

This review summarizes mechanisms underlying microbiota-gut-brain axis and novel therapeutic opportunities for neurological sequelae in preterm infants. Optimizing the initial colonization and microbiota development in preterm infants may represent a novel therapy to promote brain development and reduce long-term sequelae.

Tocolytics for delaying preterm birth: a network meta-analysis (0924)

BACKGROUND

Preterm birth is the leading cause of death in newborns and children. Tocolytic drugs aim to delay preterm birth by suppressing uterine contractions to allow time for administration of corticosteroids for fetal lung maturation, magnesium sulphate for neuroprotection, and transport to a facility with appropriate neonatal care facilities. However, there is still uncertainty about their effectiveness and safety.

OBJECTIVES

To estimate relative effectiveness and safety profiles for different classes of tocolytic drugs for delaying preterm birth, and provide rankings of the available drugs.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov (21 April 2021) and reference lists of retrieved studies.

SELECTION CRITERIA

We included all randomised controlled trials assessing effectiveness or adverse effects of tocolytic drugs for delaying preterm birth. We excluded quasi- and non-randomised trials. We evaluated all studies against predefined criteria to judge their trustworthiness.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed the trials for inclusion and risk of bias, and extracted data. We performed pairwise and network meta-analyses, to determine the relative effects and rankings of all available tocolytics. We used GRADE to rate the certainty of the network meta-analysis effect estimates for each tocolytic versus placebo or no treatment.

MAIN RESULTS

This network meta-analysis includes 122 trials (13,697 women) involving six tocolytic classes, combinations of tocolytics, and placebo or no treatment. Most trials included women with threatened preterm birth, singleton pregnancy, from 24 to 34 weeks of gestation. We judged 25 (20%) studies to be at low risk of bias. Overall, certainty in the evidence varied. Relative effects from network meta-analysis suggested that all tocolytics are probably effective in delaying preterm birth compared with placebo or no tocolytic treatment. Betamimetics are possibly effective in delaying preterm birth by 48 hours (risk ratio (RR) 1.12, 95% confidence interval (CI) 1.05 to 1.20; low-certainty evidence), and 7 days (RR 1.14, 95% CI 1.03 to 1.25; low-certainty evidence). COX inhibitors are possibly effective in delaying preterm birth by 48 hours (RR 1.11, 95% CI 1.01 to 1.23; low-certainty evidence). Calcium channel blockers are possibly effective in delaying preterm birth by 48 hours (RR 1.16, 95% CI 1.07 to 1.24; low-certainty evidence), probably effective in delaying preterm birth by 7 days (RR 1.15, 95% CI 1.04 to 1.27; moderate-certainty evidence), and prolong pregnancy by 5 days (0.1 more to 9.2 more; high-certainty evidence). Magnesium sulphate is probably effective in delaying preterm birth by 48 hours (RR 1.12, 95% CI 1.02 to 1.23; moderate-certainty evidence). Oxytocin receptor antagonists are probably effective in delaying preterm birth by 48 hours (RR 1.13, 95% CI 1.05 to 1.22; moderate-certainty evidence), are effective in delaying preterm birth by 7 days (RR 1.18, 95% CI 1.07 to 1.30; high-certainty evidence), and possibly prolong pregnancy by 10 days (95% CI 2.3 more to 16.7 more). Nitric oxide donors are probably effective in delaying preterm birth by 48 hours (RR 1.17, 95% CI 1.05 to 1.31; moderate-certainty evidence), and 7 days (RR 1.18, 95% CI 1.02 to 1.37; moderate-certainty evidence). Combinations of tocolytics are probably effective in delaying preterm birth by 48 hours (RR 1.17, 95% CI 1.07 to 1.27; moderate-certainty evidence), and 7 days (RR 1.19, 95% CI 1.05 to 1.34; moderate-certainty evidence). Nitric oxide donors ranked highest for delaying preterm birth by 48 hours and 7 days, and delay in birth (continuous outcome), followed by calcium channel blockers, oxytocin receptor antagonists and combinations of tocolytics. Betamimetics (RR 14.4, 95% CI 6.11 to 34.1; moderate-certainty evidence), calcium channel blockers (RR 2.96, 95% CI 1.23 to 7.11; moderate-certainty evidence), magnesium sulphate (RR 3.90, 95% CI 1.09 to 13.93; moderate-certainty evidence) and combinations of tocolytics (RR 6.87, 95% CI 2.08 to 22.7; low-certainty evidence) are probably more likely to result in cessation of treatment. Calcium channel blockers possibly reduce the risk of neurodevelopmental morbidity (RR 0.51, 95% CI 0.30 to 0.85; low-certainty evidence), and respiratory morbidity (RR 0.68, 95% CI 0.53 to 0.88; low-certainty evidence), and result in fewer neonates with birthweight less than 2000 g (RR 0.49, 95% CI 0.28 to 0.87; low-certainty evidence). Nitric oxide donors possibly result in neonates with higher birthweight (mean difference (MD) 425.53 g more, 95% CI 224.32 more to 626.74 more; low-certainty evidence), fewer neonates with birthweight less than 2500 g (RR 0.40, 95% CI 0.24 to 0.69; low-certainty evidence), and more advanced gestational age (MD 1.35 weeks more, 95% CI 0.37 more to 2.32 more; low-certainty evidence). Combinations of tocolytics possibly result in fewer neonates with birthweight less than 2500 g (RR 0.74, 95% CI 0.59 to 0.93; low-certainty evidence). In terms of maternal adverse effects, betamimetics probably cause dyspnoea (RR 12.09, 95% CI 4.66 to 31.39; moderate-certainty evidence), palpitations (RR 7.39, 95% CI 3.83 to 14.24; moderate-certainty evidence), vomiting (RR 1.91, 95% CI 1.25 to 2.91; moderate-certainty evidence), possibly headache (RR 1.91, 95% CI 1.07 to 3.42; low-certainty evidence) and tachycardia (RR 3.01, 95% CI 1.17 to 7.71; low-certainty evidence) compared with placebo or no treatment. COX inhibitors possibly cause vomiting (RR 2.54, 95% CI 1.18 to 5.48; low-certainty evidence). Calcium channel blockers (RR 2.59, 95% CI 1.39 to 4.83; low-certainty evidence), and nitric oxide donors probably cause headache (RR 4.20, 95% CI 2.13 to 8.25; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Compared with placebo or no tocolytic treatment, all tocolytic drug classes that we assessed (betamimetics, calcium channel blockers, magnesium sulphate, oxytocin receptor antagonists, nitric oxide donors) and their combinations were probably or possibly effective in delaying preterm birth for 48 hours, and 7 days. Tocolytic drugs were associated with a range of adverse effects (from minor to potentially severe) compared with placebo or no tocolytic treatment, although betamimetics and combination tocolytics were more likely to result in cessation of treatment. The effects of tocolytic use on neonatal outcomes such as neonatal and perinatal mortality, and on safety outcomes such as maternal and neonatal infection were uncertain.

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

BACKGROUND

Preterm birth is the major cause of perinatal mortality and morbidity worldwide. Attempts to reduce the burden may be proactive using biochemical or biophysical prediction and preventative measures. If these efforts fail, then the approach may have to be reactive using tocolytics to inhibit spontaneous preterm labour.

OBJECTIVE

We have reviewed the evidence concerning the safety and efficacy of various classes of tocolytic agents.

RESULTS

The evidence to support the use of magnesium sulfate or nitric oxide donors as a tocolytic is poor. Compared to placebo or no treatment, there is evidence to support the efficacy of calcium channel blockers (mainly nifedipine), prostaglandin synthetase inhibitors (mainly indomethacin and sulindac), oxytocin receptor antagonists (mainly atosiban) and β2-agonists (mainly ritodrine, terbutaline, salbutamol and fenoterol). Maternal safety concerns have reduced the use of β2-agonists. Fetal safety and gestational age restrictions have largely condemned prostaglandin synthetase inhibitors to second-line therapy. First-line therapy in Europe and other parts of the world outside the USA and Australia is limited to calcium channel blockers and oxytocin receptor antagonists. With respect to efficacy, atosiban and nifedipine are similar, but the robustness of the evidence favours atosiban. With respect to safety, atosiban is clearly the safest tocolytic as there are fetomaternal concerns with nifedipine, particularly in high daily doses.

CONCLUSION

The perfect tocolytic that is uniformly effective and safe does not exist. Cost, licensing and informed consent are considerations involved in the choice. Efforts continue to develop and introduce other or better agents, including novel compounds such as progesterone, PGF2α antagonists and statins.

Systematic review and meta-analysis of randomized controlled trials of atosiban versus nifedipine for inhibition of preterm labor

BACKGROUND

Two tocolytic drugs-atosiban and nifedipine-are currently used for first-line treatment of preterm labor (PTL).

OBJECTIVE

To compare the efficacy and safety of atosiban with nifedipine for PTL treatment.

SEARCH STRATEGY

In May 2017, we searched PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Clinical Trials with search terms including "nifedipine", "atosiban", and "preterm labor".

SELECTION CRITERIA

Randomized controlled trials of women with PTL.

DATA COLLECTION AND ANALYSIS

Data were extracted for study design, patient characteristics, risk of bias domains, and study outcomes. A random-effects model was used to generate pooled risk ratios (RRs) and 95% confidence intervals (CIs).

RESULTS

We included seven studies that enrolled 992 patients. There was no significant difference between atosiban and nifedipine for pregnancy prolongation of 48 hours or more regarding efficacy (RR 1.06, 95% CI 0.92-1.22; P=0.440) or effectiveness (0.93, 0.84-1.03; P=0.177). Pregnancy prolongation for 7 days or more also did not differ between groups for efficacy (RR 1.04, 95% CI 0.89-1.21; P=0.656) or effectiveness (0.91, 0.79-1.05; P=0.177). Atosiban-however-was associated with fewer maternal side-effects than nifedipine.

CONCLUSION

Atosiban resulted in fewer maternal side-effects than nifedipine, with no difference in pregnancy prolongation. PROSPERO registration: CRD42018090223.

Association of Intraventricular Hemorrhage and Death With Tocolytic Exposure in Preterm Infants

IMPORTANCE

No trials to date have demonstrated the benefits of tocolysis on death and/or neonatal morbidity in preterm infants; tocolytics may affect the fetal blood-brain barrier.

OBJECTIVES

To assess the risks associated with tocolysis in women delivering prematurely as measured by death and/or intraventricular hemorrhage (IVH) in preterm infants and to compare the association of calcium channel blockers (CCBs) nifedipine and nicardipine hydrochloride vs atosiban used for tocolysis with death and/or IVH.

DESIGN, SETTINGS, AND PARTICIPANTS

The French 2011 EPIPAGE-2 (Enquête Épidémiologique sur les Petits Âges Gestationnels) cohort was limited to mothers admitted for preterm labor without fever, who delivered from 24 to 31 weeks of gestation from April 1 through December 31, 2011. Groups of preterm infants with vs without tocolytic exposure and groups with atosiban vs CCB exposure were compared. Data analysis was performed from June 7, 2014, through September 3, 2017.

EXPOSURES

Tocolytics.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of death and/or IVH in preterm infants. Secondary outcomes included death, IVH, and a composite of death and/or grades III to IV IVH.

RESULTS

A total of 1127 mothers (mean [SD] age, 25.5 [6.0] years) experienced preterm labor and gave birth to 1343 preterm infants with a male to female ratio of 1.23 and mean (SD) gestational age of 27 (2.5) weeks. Of these, 789 mothers (70.0%) received tocolytics; 314 (39.8%) received only atosiban, and 118 (15.0%) received only a CCB. In the first analysis, the primary outcome (death and/or IVH) was not significantly different in preterm infants with vs without tocolytic exposure (183 of 363 [50.4%] vs 207 of 363 [57.0%]; relative risk [RR], 0.88; 95% CI, 0.77-1.01; P = .07). The secondary outcome (death and/or grades III-IV IVH) was significantly lower in preterm infants with vs without tocolytic exposure (92 of 363 [25.3%] vs 118 of 363 [32.5%]; RR, 0.78; 95% CI, 0.62-0.98; P = .03). Other outcomes did not differ significantly. In the secondary analysis, death and/or IVH was not significantly different in preterm infants with atosiban vs CCB exposure (96 of 214 [44.9%] vs 62 of 121 [51.2%]; RR, 0.88; 95% CI, 0.70-1.10; P = .26), nor was IVH (77 of 197 [39.1%] vs 48 of 106 [45.3%]; RR, 0.86; 95% CI, 0.66-1.13; P = .29).

CONCLUSIONS AND RELEVANCE

In this population-based study, findings suggest that tocolytics were associated with a reduction of death and severe IVH. Other studies are necessary to compare perinatal outcomes after use of atosiban vs CCBs.