Use of tocolytics: what is the benefit of gaining 48 hours for the fetus?

Hexoprenaline Compared with Atosiban as Tocolytic Treatment for Preterm Labor

Introduction Preterm birth is defined as a live birth before 37 weeks of gestation and is associated with increased neonatal morbidity and mortality. The aim of this study is to compare the efficacy of hexoprenaline and atosiban for short- and long-term tocolysis and their effects on neonatal and maternal outcomes.

Methods This retrospective cohort study included women with threatened preterm labor between 24 + 0 and 34 + 0 weeks of gestation without premature rupture of membranes. The tocolytic efficacy of hexoprenaline and atosiban was compared in women receiving one of the two medications for short- and long-term tocolysis. Continuous variables were compared using t-test or Mann–Whitney U test, as appropriate. Comparison of categorical variables between the two groups was done with χ ² test after Pearsonʼs and Fisherʼs exact test.

Results 761 women were enrolled in this study; 387 women received atosiban and 374 women received hexoprenaline as their primary tocolytic agent. Atosiban showed a higher efficacy as a primary tocolytic agent (p = 0.000) within 48 hours. As regards long-term tocolysis, there were no differences between the treatment groups (p = 0.466). Maternal side effects such as tachycardia (p = 0.018) or palpitations (p = 0.000) occurred more frequently after the administration of hexoprenaline, while there were no differences between the two drugs administered with regard to any other maternal or neonatal outcome parameter.

Conclusion Our retrospective study shows a significantly higher efficacy of atosiban in the first 48 hours, especially when administered at an early gestational age. There were no significant differences in terms of neonatal outcome but significantly more maternal adverse effects during the administration of hexoprenaline.

Intensity of perinatal care for extremely preterm infants: outcomes at 2.5 years

OBJECTIVE

To examine the association between intensity of perinatal care and outcome at 2.5 years' corrected age (CA) in extremely preterm (EPT) infants (<27 weeks) born in Sweden during 2004-2007.

METHODS

A national prospective study in 844 fetuses who were alive at the mother's admission for delivery: 707 were live born, 137 were stillborn. Infants were assigned a perinatal activity score on the basis of the intensity of care (rates of key perinatal interventions) in the infant's region of birth. Scores were calculated separately for each gestational week (gestational age [GA]-specific scores) and for the aggregated cohort (aggregated activity scores). Primary outcomes were 1-year mortality and death or neurodevelopmental disability (NDI) at 2.5 years' CA in fetuses who were alive at the mother's admission.

RESULTS

Each 5-point increment in GA-specific activity score reduced the stillbirth risk (adjusted odds ratio [aOR]: 0.90; 95% confidence interval [CI]: 0.83-0.97) and the 1-year mortality risk (aOR: 0.84; 95% CI: 0.78-0.91) in the primary population and the 1-year mortality risk in live-born infants (aOR: 0.86; 95% CI: 0.79-0.93). In health care regions with higher aggregated activity scores, the risk of death or NDI at 2.5 years' CA was reduced in the primary population (aOR: 0.69; 95% CI: 0.50-0.96) and in live-born infants (aOR: 0.68; 95% CI: 0.48-0.95). Risk reductions were confined to the 22- to 24-week group. There was no difference in NDI risk between survivors at 2.5 years' CA.

CONCLUSIONS

Proactive perinatal care decreased mortality without increasing the risk of NDI at 2.5 years' CA in EPT infants. A proactive approach based on optimistic expectations of a favorable outcome is justified.

Oxidative stress damage as a detrimental factor in preterm birth pathology

Normal term and spontaneous preterm births (PTB) are documented to be associated with oxidative stress (OS), and imbalances in the redox system (balance between pro- and antioxidant) have been reported in the maternal-fetal intrauterine compartments. The exact mechanism of labor initiation either at term or preterm by OS is still unclear, and this lack of understanding can partially be blamed for failure of antioxidant supplementation trials in PTB prevention. Based on recent findings from our laboratory, we postulate heterogeneity in host OS response. The physiologic (at term) and pathophysiologic (preterm) pathways of labor are not mediated by OS alone but by OS-induced damage to intrauterine tissues, especially fetal membranes of the placenta. OS damage affects all major cellular elements in the fetal cells, and this damage promotes fetal cell senescence (aging). The aging of the fetal cells is predominated by p38 mitogen activated kinase (p38MAPK) pathways. Senescing cells generate biomolecular signals that are uterotonic, triggering labor process. The aging of fetal cells is normal at term. However, aging is premature in PTB, especially in those PTBs complicated by preterm premature rupture of the membranes, where elements of redox imbalances and OS damage are more dominant. We postulate that fetal cell senescence signals generated by OS damage are likely triggers for labor. This review highlights the mechanisms involved in senescence development at term and preterm by OS damage and provides insight into novel fetal signals of labor initiation pathways.

A blueprint for the prevention of preterm birth: vaginal progesterone in women with a short cervix

Preterm birth is the leading cause of perinatal morbidity and mortality worldwide, and is the most important challenge to modern obstetrics. A major obstacle has been that preterm birth is treated (implicitly or explicitly) as a single condition. Two thirds of preterm births occur after the spontaneous onset of labor, and the remaining one third after "indicated" preterm birth; however, the causes of spontaneous preterm labor and "indicated" preterm birth are different. Spontaneous preterm birth is a syndrome caused by multiple etiologies, one of which is a decline in progesterone action, which induces cervical ripening. A sonographic short cervix (identified in the midtrimester) is a powerful predictor of spontaneous preterm delivery. Randomized clinical trials and individual patient meta-analyses have shown that vaginal progesterone reduces the rate of preterm delivery at <33 weeks of gestation by 44%, along with the rate of admission to the neonatal intensive care unit, respiratory distress syndrome, requirement for mechanical ventilation, and composite neonatal morbidity/mortality score. There is no evidence that 17-α-hydroxyprogesterone caproate can reduce the rate of preterm delivery in women with a short cervix, and therefore, the compound of choice is natural progesterone (not the synthetic progestin). Routine assessment of the risk of preterm birth with cervical ultrasound coupled with vaginal progesterone for women with a short cervix is cost-effective, and the implementation of such a policy is urgently needed. Vaginal progesterone is as effective as cervical cerclage in reducing the rate of preterm delivery in women with a singleton gestation, history of preterm birth, and a short cervix (<25 mm).

Prevention of preterm labour: 2011 update on tocolysis

The aim of this paper is to review available data about drugs for preventing preterm labour. Tocolytic therapy includes β adrenergic receptor agonists, NO donors, magnesium sulphate, prostaglandin-synthase inhibitors, oxytocin receptor antagonists, calcium-channel blockers, progesterone, 17-α-hydroxyprogesterone caproate, and antibiotics. Their specific effects on myometrial contractility, their safety, their efficiency, and side effects profile for the mother and the fetus are presented. The main question of why and for what reasons tocolysis should be administrated is discussed.

Magnesium sulfate: past, present, and future

First used anecdotally for the control of eclamptic seizures in the early 1900s, magnesium sulfate remains 1 of the most commonly used medications in obstetric practice today. Over the past 95 years, there have been countless research studies investigating the efficacy of magnesium sulfate for the management of eclampsia, preeclampsia, preterm labor, and most recently for prevention of cerebral palsy. The majority of this evidence undeniably supports the use of magnesium sulfate as the drug of choice for the prevention and treatment of eclampsia when evidence of severe disease is present. On the other hand, studies have not shown magnesium sulfate to be comparably more effective than other tocolytics for treating preterm labor, nor is there agreement on whether the evidence supports its use as a neuroprotective agent for prevention of cerebral palsy. The exact mechanism of action of magnesium sulfate remains largely hypothetical, and parenteral use has the potential to cause significant morbidity in high doses. This article reviews magnesium sulfate's remarkable history in obstetric practice and includes a summary of the evidence related to each of the controversies. An initial review of the physiology of magnesium sulfate is essential to understanding pharmacodynamic actions, dosing guidelines, and safety requirements.

Atosiban in the Management of Preterm Labour

The purpose of this review was to look at the evidence available for the use of atosiban as a tocolytic in cases of threatened preterm labour. A Royal College of Obstetricians and Gynaecologists Green Top Guideline concluded that there was no clear evidence to show a benefit to tocolysis in reducing perinatal and neonatal morbidity and mortality. Using a systematic literature search, we summarise the evidence available on the use of atosiban for the prevention of preterm birth and compare it with other commonly used tocolytic agents in terms of efficacy, patient preference and drug safety. We conclude that although atosiban appears to be the tocolytic of choice, a clear benefit of using tocolysis in all cases of threatened preterm labour remains to be justified and clinical management should be tailored according to individual needs.

Guideline for the use of antenatal corticosteroids for fetal maturation

The aim is to present a document, which is based on current evidence and serves as a guideline for use in clinical practice. The following questions are addressed: Is the use of antenatal corticosteroids (ACS) an effective therapy? Who are the candidates for antenatal corticosteroid therapy? Is there benefit after 34 weeks' gestation? When is the optimal time to treat? Which are the optimal steroids; what is the ideal dose and route of administration? Are there any contraindications to the administration of ACS? Are antenatal corticosteroids indicated in women with premature rupture of membranes (PROM)? Is the use of ACS recommended in pregnancies complicated by maternal diabetes mellitus? Should the treatment with corticosteroids be repeated?

The choice of a tocolytic for the treatment of preterm labor: a critical evaluation of nifedipine versus atosiban

Preterm birth is the major cause of neonatal mortality and morbidity in the developed world. The perfect tocolytic that is uniformly effective with complete fetomaternal safety does not exist. Tocolytic agents differ in cost, utero-specificity, safety, efficacy and whether they are licensed for use. The main three agents that are used worldwide are beta-agonists, Ca(2+) channel blockers and vasopressin/oxytocin receptor antagonists. beta-Agonists are gradually being phased out of use and are being replaced by either nifedipine or atosiban. The evidence base for atosiban is strong but the evidence is of poor quality for nifedipine. The balance of evidence indicates that atosiban is as effective as nifedipine and more effective than beta-agonists and is significantly safer than both. Atosiban was developed specifically to treat preterm labor, so the cost is higher than nifedipine or ritodrine. However, the cost of a course of atosiban (approximately 200 pounds) should not only be considered in comparison with other tocolytic agents but to other medical budgets (e.g., oncology, fertility, cardiology and psychiatry) and to the huge healthcare costs associated with the morbidity and mortality caused by preterm birth. Atosiban is a new advance in the management of spontaneous preterm labor.