Rofecoxib Versus Magnesium Sulfate to Arrest Preterm Labor: A Randomized Trial

Preterm Birth Therapies to Target Inflammation

Preterm birth (PTB; defined as delivery before 37 weeks of pregnancy) is the leading cause of morbidity and mortality in infants and children aged <5 years, conferring potentially devastating short‐ and long‐term complications. Despite extensive research in the field, there is currently a paucity of medications available for PTB prevention and treatment. Over the past few decades, inflammation in gestational tissues has emerged at the forefront of PTB pathophysiology. Even in the absence of infection, inflammation alone can prematurely activate the main components of parturition resulting in uterine contractions, cervical ripening and dilatation, membrane rupture, and subsequent PTB. Mechanistic studies have identified critical elements of the complex inflammatory molecular pathways involved in PTB. Here, we discuss therapeutic options that target such key mediators with an aim to prevent, postpone, or treat PTB. We provide an overview of more traditional therapies that are currently used or being tested in humans, and we highlight recent advances in preclinical studies introducing novel approaches with therapeutic potential. We conclude that urgent collaborative action is required to address the unmet need of developing effective strategies to tackle the challenge of PTB and its complications.

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.

Preoperative paracetamol improves post-cesarean delivery pain management: a prospective, randomized, double-blind, placebo-controlled trial

STUDY OBJECTIVE

To evaluate the analgesic effect of preoperative single dose intravenous paracetamol on postoperative pain and analgesic consumption within 24hours after elective cesarean surgery.

DESIGN

Prospective, randomized, double-blind, placebo-controlled clinical trial.

SETTING

University Teaching Hospital.

PATIENTS

American Society of Anesthesiologists (ASA) I and II 60 patients between 18-40years of age who were scheduled to undergo elective cesarean section.

INTERVENTIONS

Patients were randomized into two groups to receive either intravenous 1g paracetamol (100mL) (Group P) or 0.9% NaCl solution (100mL) (Group C) 15minutes before the induction of general anesthesia. After delivery of newborn 0.15mg kg(-1) morphine was administered to all patients in both groups. Postoperative analgesia was provided with patient-controlled intravenous analgesia with morphine in the postoperative period.

MEASUREMENTS

Pain which is the primary outcome measure was assessed at 15th, 30th minutes and 1st, 2nd, 4th, 6th, 12th, 24th hours by the Visual Analogue Scale. Patients' demographics, hemodynamics, Apgar score, additional analgesic requirement, side effects, patients' satisfaction and postoperative total morphine consumption within 24hours were recorded.

MAIN RESULTS

Median visual analogue scale for pain in Group P was significantly lower compared to Group C at all time points except for the score at 24th h postoperatively (P<.05). Additional analgesic requirement during postoperative first hour was lower in Group P (P<.05). Total morphine consumption was higher in Group C compared with Group P (P<.05). There was no difference between groups with respect to Apgar scores, side effects, and patient satisfaction (P>.05).

CONCLUSIONS

Preoperative use of single-dose intravenous 1g paracetamol was found to be effective in reducing the severity of pain and opioid requirements within 24hours after cesarean section.

Different treatment regimens of magnesium sulphate for tocolysis in women in preterm labour

BACKGROUND

Magnesium sulphate has been used to inhibit preterm labour to prevent preterm birth. There is no consensus as to the safety profile of different treatment regimens with respect to dose, duration, route and timing of administration.

OBJECTIVES

To assess the efficacy and safety of alternative magnesium sulphate regimens when used as single agent tocolytic therapy during pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised trials comparing different magnesium sulphate treatment regimens when used as single agent tocolytic therapy during pregnancy in women in preterm labour. Quasi-randomised trials were eligible for inclusion but none were identified. Cross-over and cluster trials were not eligible for inclusion. Health outcomes were considered at the level of the mother, the infant/child and the health service.

INTERVENTION

intravenous or oral magnesium sulphate given alone for tocolysis.Comparison: alternative dosing regimens of magnesium sulphate given alone for tocolysis.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility and quality and extracted data.

MAIN RESULTS

Three trials including 360 women and their infants were identified as eligible for inclusion in this review. Two trials were rated as low risk of bias for random sequence generation and concealment of allocation. A third trial was assessed as unclear risk of bias for these domains but did not report data for any of the outcomes examined in this review. No trials were rated to be of high quality overall.Intravenous magnesium sulphate was administered according to low-dose regimens (4 g loading dose followed by 2 g/hour continuous infusion and/or increased by 1 g/hour hourly until successful tocolysis or failure of treatment), or high-dose regimens (4 g loading dose followed by 5 g/hour continuous infusion and increased by 1 g/hour hourly until successful tocolysis or failure of treatment, or 6 g loading dose followed by 2 g/hour continuous infusion and increased by 1 g/hour hourly until successful tocolysis or failure of treatment).There were no differences seen between high-dose magnesium sulphate regimens compared with low-dose magnesium sulphate regimens for the primary outcome of fetal, neonatal and infant death (risk ratio (RR) 0.43, 95% confidence interval (CI) 0.12 to 1.56; one trial, 100 infants). Using the GRADE approach, the evidence for fetal, neonatal and infant death was considered to be VERY LOW quality. No data were reported for any of the other primary maternal and infant health outcomes (birth less than 48 hours after trial entry; composite serious infant outcome; composite serious maternal outcome).There were no clear differences seen between high-dose magnesium sulphate regimens compared with low-dose magnesium sulphate regimens for the secondary infant health outcomes of fetal death; neonatal death; and rate of hypocalcaemia, osteopenia or fracture; and secondary maternal health outcomes of rate of caesarean birth; pulmonary oedema; and maternal self-reported adverse effects. Pulmonary oedema was reported in two women given high-dose magnesium sulphate, but not in any of the women given low-dose magnesium sulphate.In a single trial of high and low doses of magnesium sulphate for tocolysis including 100 infants, the risk of respiratory distress syndrome was lower with use of a high-dose regimen compared with a low-dose regimen (RR 0.31, 95% CI 0.11 to 0.88; one trial, 100 infants). Using the GRADE approach, the evidence for respiratory distress syndrome was judged to be LOW quality. No difference was seen in the rate of admission to the neonatal intensive care unit. However, for those babies admitted, a high-dose regimen was associated with a reduction in the length of stay in the neonatal intensive care unit compared with a low-dose regimen (mean difference -3.10 days, 95% confidence interval -5.48 to -0.72).We found no data for the majority of our secondary outcomes.

AUTHORS' CONCLUSIONS

There are limited data available (three studies, with data from only two studies) comparing different dosing regimens of magnesium sulphate given as single agent tocolytic therapy for the prevention of preterm birth. There is no evidence examining duration of therapy, timing of therapy and the role for repeat dosing.Downgrading decisions for our primary outcome of fetal, neonatal and infant death were based on wide confidence intervals (crossing the line of no effect), lack of blinding and a limited number of studies. No data were available for any of our other important outcomes: birth less than 48 hours after trial entry; composite serious infant outcome; composite serious maternal outcome. The data are limited by volume and the outcomes reported. Only eight of our 45 pre-specified primary and secondary maternal and infant health outcomes were reported on in the included studies. No long-term outcomes were reported. Downgrading decisions for the evidence on the risk of respiratory distress were based on wide confidence intervals (crossing the line of no effect) and lack of blinding.There is some evidence from a single study suggesting a reduction in the length of stay in the neonatal intensive care unit and a reduced risk of respiratory distress syndrome where a high-dose regimen of magnesium sulphate has been used compared with a low-dose regimen. However, given that evidence has been drawn from a single study (with a small sample size), these data should be interpreted with caution.Magnesium sulphate has been shown to be of benefit in a wide range of obstetric settings, although it has not been recommended for tocolysis. In clinical settings where health benefits are established, further trials are needed to address the lack of evidence regarding the optimal dose (loading dose and maintenance dose), duration of therapy, timing of therapy and role for repeat dosing in terms of efficacy and safety for mothers and their children. Ongoing examination of different regimens with respect to important health outcomes is required.

Cyclo-oxygenase (COX) inhibitors for treating preterm labour

BACKGROUND

Preterm birth is a major cause of perinatal mortality and morbidity. Cyclo-oxygenase (COX) inhibitors inhibit uterine contractions, are easily administered and appear to have few maternal side effects. However, adverse effects have been reported in the fetus and newborn as a result of exposure to COX inhibitors.

OBJECTIVES

To assess the effects on maternal and neonatal outcomes of COX inhibitors administered as a tocolytic agent to women in preterm labour when compared with (i) placebo or no intervention and (ii) other tocolytics. In addition, to compare the effects of non-selective COX inhibitors with COX-2 selective inhibitors.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (24 August 2014). We also contacted recognised experts and searched reference lists of retrieved studies.

SELECTION CRITERIA

All published and unpublished randomised trials in which COX inhibitors were used for tocolysis for women in labour between 20 and 36 completed weeks' gestation.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated methodological quality and extracted data. We sought additional information from study authors. Results are presented using risk ratio (RR; dichotomous data) and mean difference (MD; continuous data) with 95% confidence interval (CI). The number needed to treat for benefit (NNTB) and the number needed to treat for harm (NNTH) were calculated for statistically different categorical outcomes.

MAIN RESULTS

With the addition of seven studies with a total of 684 women, this review now includes outcome data from 20 studies including 1509 women. The non-selective COX inhibitor indomethacin was used in 15 studies. The overall quality of the included studies was considered moderate to low.Three small studies (102 women), two of which were conducted in the 1980's, compared COX inhibition (indomethacin only) with placebo. No difference was shown in birth less than 48 hours after trial entry (average RR 0.20, 95% CI 0.03 to 1.28; two studies with 70 women). Indomethacin resulted in a reduction in preterm birth (before completion of 37 weeks of gestation) in one small study (36 women) (RR 0.21, 95% CI 0.07 to 0.62; NNTB 2, 95% CI 2 to 4); and an increase in gestational age at birth (average MD 3.59 weeks, 95% CI 0.65 to 6.52; two studies with 66 women) and birthweight (MD 716.34 g, 95% CI 425.52 to 1007.16; two studies with 67 infants). No difference was shown in measures of neonatal morbidity or neonatal mortality.Compared with betamimetics, COX inhibitors resulted in a reduction in birth less than 48 hours after trial entry (RR 0.27, 95% CI 0.08 to 0.96; NNTB 7, 95% CI 6 to 120; two studies with 100 women) and preterm birth (before completion of 37 weeks of gestation) (RR 0.53, 95% CI 0.28 to 0.99; NNTB 6, 95% CI 4 to 236; two studies with 80 women) although no benefit was shown in terms of neonatal morbidity or mortality. COX inhibition was also associated with fewer maternal adverse affects compared with betamimetics (RR 0.19, 95% CI 0.11 to 0.31; NNTB 3, 95% CI 2 to 3; five studies with 248 women) and maternal adverse effects requiring cessation of treatment (average RR 0.09, 95% CI 0.02 to 0.49; NNTB 5, CI 95% 5 to 9; three studies with 166 women).No differences were shown when comparing COX inhibitors with magnesium sulphate (MgSO4) (seven studies with 792 women) or calcium channel blockers (CCBs) (two studies with 230 women) in terms of prolonging pregnancy or for any fetal/neonatal outcomes. There were also no differences in very preterm birth (before completion of 34 weeks of gestation) and no maternal deaths occurred in the one study that reported on this outcome. However COX inhibitors resulted in fewer maternal adverse affects when compared with MgSO4 (RR 0.39, 95% CI 0.25 to 0.62; NNTB 11, 95% CI 9 to 17; five studies with 635 women).A comparison of non-selective COX inhibitors versus any COX-2 inhibitor (two studies with 54 women) did not demonstrate any differences in maternal, fetal or neonatal outcomes.No data were available to assess COX inhibitors compared with oxytocin receptor antagonists (ORAs). Further, no data were available on extremely preterm birth (before 28 weeks of gestation), longer-term infant outcomes or costs.

AUTHORS' CONCLUSIONS

In this review, no clear benefit for COX inhibitors was shown over placebo or any other tocolytic agents. While some benefit was demonstrated in terms of postponement of birth for COX inhibitors over placebo and betamimetics and also maternal adverse effects over betamimetics and MgSO4, due to the limitations of small numbers, minimal data on safety, lack of longer-term outcomes and generally low quality of the studies included in this review, we conclude that there is insufficient evidence on which to base decisions about the role of COX inhibition for women in preterm labour. Further well-designed tocolytic studies are required to determine short- and longer-term infant benefit of COX inhibitors over placebo and other tocolytics, particularly CCBs and ORAs. Another important focus for future studies is identifying whether COX-2 inhibitors are superior to non-selective COX inhibitors. All future studies on tocolytics for women in preterm labour should assess longer-term effects into early childhood and also costs.

Using celecoxib for the suppression of preterm labor instead of magnesium sulfate

We aimed to use celecoxib to suppress preterm labor instead magnesium sulfate (MgSO₄) to prevent preterm labor. Methods. It was a randomized clinical trial study, which was done on 600 pregnant women. All subjects were divided into two groups by simple random sampling. One group was given 4 grams of MgSO₄ intravenously and second group was given 100 mg of celecoxib orally every 12 hours for at least 2 days. The data were entered and analyzed using SPSS 11 and performed using t-test and chi-square test. Results. The finding of this study has shown that preterm labor may be prevented in 75.7% of subjects who had received celecoxib and there were no significant difference between two groups in frequency of history of preterm labor (P = 1), frequencies of nulliparity (P = 0.99), duration of drug use and arrest contraction (P = 0.29), delivery before 48 hours (P = 0.20), and mean gestational age in lack of response to treatment (P = 0.24). Conclusions. Result has shown that celecoxib was similar to MgSO₄ as a medication to prevent preterm labor; it was recommended to be prescribe to prevent preterm labor, because it was cheaper than magnesium sulfate.

Magnesium sulphate for preventing preterm birth in threatened preterm labour

BACKGROUND

Magnesium sulphate has been used in some settings as a tocolytic agent to inhibit uterine activity in women in preterm labour with the aim of preventing preterm birth.

OBJECTIVES

To assess the effects of magnesium sulphate therapy given to women in threatened preterm labour with the aim of preventing preterm birth and its sequelae.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (last searched 31 January 2014).

SELECTION CRITERIA

Randomised controlled trials of magnesium sulphate as the only tocolytic, administered by any route, compared with either placebo, no treatment or alternative tocolytic therapy (not magnesium sulphate) to women considered to be in preterm labour.

DATA COLLECTION AND ANALYSIS

At least two review authors assessed trial eligibility and risk of bias and undertook data extraction independently.

MAIN RESULTS

The 37 included trials (total of 3571 women and over 3600 babies) were generally of moderate to high risk of bias. Antenatal magnesium sulphate was compared with either placebo, no treatment, or a range of alternative tocolytic agents.For the primary outcome of giving birth within 48 hours after trial entry, no significant differences were seen between women who received magnesium sulphate and women who did not (whether placebo/no alternative tocolytic drug, betamimetics, calcium channel blockers, cox inhibitors, prostaglandin inhibitors, or human chorionic gonadotropin) (19 trials, 1913 women). Similarly for the primary outcome of serious infant outcome, there were no significant differences between the infants exposed to magnesium sulphate and those not (whether placebo/no alternative tocolytic drug, betamimetics, calcium channel blockers, cox inhibitors, prostaglandin inhibitors, human chorionic gonadotropin or various tocolytic drugs) (18 trials; 2187 babies). No trials reported the outcome of extremely preterm birth. In the seven trials that reported serious maternal outcomes, no events were recorded.In the group treated with magnesium sulphate compared with women receiving antenatal placebo or no alternative tocolytic drug, a borderline increased risk of total death (fetal, neonatal, infant) was seen (risk ratio (RR) 4.56, 95% confidence interval (CI) 1.00 to 20.86; two trials, 257 babies); none of the comparisons between magnesium sulphate and other classes of tocolytic drugs showed differences for this outcome (10 trials, 991 babies). The outcomes of neonatal and/or infant deaths and of fetal deaths did not show differences between magnesium sulphate and no magnesium sulphate, whether compared with placebo/no alternative tocolytic drug, or any specific class of tocolytic drug. For most of the other secondary outcomes, there were no significant differences between magnesium sulphate and the control groups for risk of preterm birth (except for a significantly lower risk with magnesium sulphate when compared with barbiturates in one trial of 65 women), gestational age at birth, interval between trial entry and birth, other neonatal morbidities, or neurodevelopmental outcomes. Duration of neonatal intensive care unit stay was significantly increased in the magnesium sulphate group compared with the calcium channel blocker group, but not when compared with cox inhibitors or prostaglandin inhibitors. No maternal deaths were reported in the four trials reporting this outcome. Significant differences between magnesium sulphate and controls were not seen for maternal adverse events severe enough to stop treatment, except for a significant benefit of magnesium sulphate compared with betamimetics in a single trial.

AUTHORS' CONCLUSIONS

Magnesium sulphate is ineffective at delaying birth or preventing preterm birth, has no apparent advantages for a range of neonatal and maternal outcomes as a tocolytic agent and its use for this indication may be associated with an increased risk of total fetal, neonatal or infant mortality (in contrast to its use in appropriate groups of women for maternal, fetal, neonatal and infant neuroprotection where beneficial effects have been demonstrated).

Tocolytic therapy for preterm delivery: systematic review and network meta-analysis

OBJECTIVE

To determine the most effective tocolytic agent at delaying delivery.

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

Cochrane Central Register of Controlled Trials, Medline, Medline In-Process, Embase, and CINAHL up to 17 February 2012.

STUDY SELECTION

Randomised controlled trials of tocolytic therapy in women at risk of preterm delivery.

DATA EXTRACTION

At least two reviewers extracted data on study design, characteristics, number of participants, and outcomes reported (neonatal and maternal). A network meta-analysis was done using a random effects model with drug class effect. Two sensitivity analyses were carried out for the primary outcome; restricted to studies at low risk of bias and restricted to studies excluding women at high risk of preterm delivery (those with multiple gestation and ruptured membranes).

RESULTS

Of the 3263 titles initially identified, 95 randomized controlled trials of tocolytic therapy were reviewed. Compared with placebo, the probability of delivery being delayed by 48 hours was highest with prostaglandin inhibitors (odds ratio 5.39, 95% credible interval 2.14 to 12.34) followed by magnesium sulfate (2.76, 1.58 to 4.94), calcium channel blockers (2.71, 1.17 to 5.91), beta mimetics (2.41, 1.27 to 4.55), and the oxytocin receptor blocker atosiban (2.02, 1.10 to 3.80). No class of tocolytic was significantly superior to placebo in reducing neonatal respiratory distress syndrome. Compared with placebo, side effects requiring a change of medication were significantly higher for beta mimetics (22.68, 7.51 to 73.67), magnesium sulfate (8.15, 2.47 to 27.70), and calcium channel blockers (3.80, 1.02 to 16.92). Prostaglandin inhibitors and calcium channel blockers were the tocolytics with the best probability of being ranked in the top three medication classes for the outcomes of 48 hour delay in delivery, respiratory distress syndrome, neonatal mortality, and maternal side effects (all cause).

CONCLUSIONS

Prostaglandin inhibitors and calcium channel blockers had the highest probability of delaying delivery and improving neonatal and maternal outcomes.

Cyclooxygenase immunohistochemical staining in the human ductus arteriosus after 24 weeks of gestational age

Cyclooxygenase inhibitors (CI) which contained risks to fetal health were one of the most effective tocolytics. In order to indirectly investigate the effects of CI in human ductus arteriosus, immunohistochemical staining for cyclooxygenase-1 (COX1) and cyclooxygenase-2 (COX2) was evaluated in post-mortem fetuses with gestational ages between 24 and 34 weeks. Neither COX1 nor COX2 staining was related to gestational age. COX1 and COX2 staining in the vessel walls were not related to each other. COX1 staining in the endothelium, inner media and outer media were positively correlated with each other (COX1 endothelium vs IM staining Spearman's rho statistic [rs] = 0.721, p = 0.001; COX1 endothelium vs OM staining [rs] = 0.634, p = 0.004; COX1 IM vs OM staining [rs] = 0.931, p = 0.001). COX2 staining of endothelium was not correlated with either IM or OM staining. In conclusion, COX2 staining in the post-mortem specimens of human ductus arteriosus between 24 and 34 weeks is weak and limited to the endothelium.

Magnesium sulfate therapy for the prevention of cerebral palsy in preterm infants: a decision-analytic and economic analysis

OBJECTIVE

We sought to estimate the cost-effectiveness of magnesium neuroprophylaxis for all women at risk for preterm birth <32 weeks.

STUDY DESIGN

A decision analytic and cost-effectiveness model was designed to compare use of magnesium for neuroprophylaxis vs no treatment for women at risk for preterm birth <32 weeks due to preterm premature rupture of membranes or preterm labor from 24-32 weeks. Outcomes included neonatal death and moderate-severe cerebral palsy. Effectiveness was reported in quality-adjusted life years.

RESULTS

Magnesium for neuroprophylaxis led to lower costs ($1739 vs $1917) and better outcomes (56.684 vs 56.678 quality-adjusted life years). However, sensitivity analysis revealed the model to be sensitive to estimates of effect of magnesium on risk of moderate or severe cerebral palsy as well as neonatal death.

CONCLUSION

Based on currently published evidence for efficacy, magnesium for neuroprophylaxis in women at risk to deliver preterm is cost-effective.

Prematurity prevention: the role of acute tocolysis

PURPOSE OF REVIEW

The preterm birth rate in the United States remains at an all-time high and continues to rise. Acute tocolysis has potential to delay preterm birth for 48 h, the critical period of antenatal steroid administration, or to arrest an episode of preterm labor, thus delaying birth and improving neonatal outcomes. It is therefore paramount that medical providers remain up-to-date regarding the usefulness, indications and contraindications, and side-effects and adverse effects of all tocolytics.

RECENT FINDINGS

Magnesium sulfate remains the most common tocolyic agent in the United States. Recent evidence comparing oral nifedipine with magnesium sulfate suggests equal efficacy with fewer maternal side-effects, thus supporting this oral medication as first-line treatment. This review will summarize the most common acute tocolytic drugs, their methods of action, and clinical data regarding their utility.

SUMMARY

All tocolytic medications have side-effects, some of them potentially life-threatening. Decisions regarding whether to use a tocolytic and which tocolytic to use require the diagnosis of preterm labor, knowledge of the patient's gestational age, medical conditions, and cost. Once tocolysis is initiated, attention must be paid to the patient's response, side-effects, and adverse events. Larger studies are needed which incorporate, in addition to efficacy, data on safety and side-effect profiles and cost.

In defense of magnesium sulfate

Magnesium sulfate has been used by obstetricians for more than 25 years to treat preterm labor. Magnesium sulfate is effective in delaying delivery for at least 48 hours in patients with preterm labor when used in higher dosages. There do not seem to be any harmful effects of the drug on the fetus, and indeed there is a neuroprotective effect in reducing the incidence of cerebral palsy in premature newborns weighing less than 1,500 g.

Tocolytic therapy: a meta-analysis and decision analysis

OBJECTIVE

To determine the optimal first-line tocolytic agent for treatment of premature labor.

METHODS

We performed a quantitative analysis of randomized controlled trials of tocolysis, extracting data on maternal and neonatal outcomes, and pooling rates for each outcome across trials by treatment. Outcomes were delay of delivery for 48 hours, 7 days, and until 37 weeks; adverse effects causing discontinuation of therapy; absence of respiratory distress syndrome; and neonatal survival. We used weighted proportions from a random-effects meta-analysis in a decision model to determine the optimal first-line tocolytic therapy. Sensitivity analysis was performed using the standard errors of the weighted proportions.

RESULTS

Fifty-eight studies satisfied the inclusion criteria. A random-effects meta-analysis showed that all tocolytic agents were superior to placebo or control groups at delaying delivery both for at least 48 hours (53% for placebo compared with 75-93% for tocolytics) and 7 days (39% for placebo compared with 61-78% for tocolytics). No statistically significant differences were found for the other outcomes, including the neonatal outcomes of respiratory distress and neonatal survival. The decision model demonstrated that prostaglandin inhibitors provided the best combination of tolerance and delayed delivery. In a hypothetical cohort of 1,000 women receiving prostaglandin inhibitors, only 80 would deliver within 48 hours, compared with 182 for the next-best treatment.

CONCLUSION

Although all current tocolytic agents were superior to no treatment at delaying delivery for both 48 hours and 7 days, prostaglandin inhibitors were superior to the other agents and may be considered the optimal first-line agent before 32 weeks of gestation to delay delivery.

Celecoxib versus magnesium sulfate to arrest preterm labor: randomized trial

AIM

The effectiveness of the management of preterm birth remains an important health care issue, especially when considering that more than two thirds of singleton neonatal death occurs in preterm labor. The purpose of this study was to compare oral celecoxib with intravenous magnesium sulfate as tocolytic.

METHODS

This was a randomized study of patients who were between 24 and 34 weeks of gestation with preterm labor. One hundred and four pregnant women with preterm labor were randomly assigned to receive celecoxib 100 mg b.i.d. for 48 h or intravenous magnesium sulfate (MgSO4) for maximum of 48 h. Outcome variables included delay of delivery for 48 h and the incidence of side-effects. Data was analyzed using the Student t-test and the chi(2) test.

RESULTS

There was no difference between the groups over the course of the study in demographic characteristics, cervical examination and amniotic fluid index. Labor was arrested for 48 h was in 42 (81%) and 45 (87%) of the patients in the celecoxib and magnesium sulfate groups, respectively (p-0.298). There were no severe maternal or neonatal complications in either group.

CONCLUSION

Celecoxib is as effective as magnesium sulfate for primary tocolysis.

A cost decision analysis of 4 tocolytic drugs

OBJECTIVE

The purpose of this study was to determine the optimal tocolytic agent, based on a cost decision analysis.

STUDY DESIGN

A PubMed search of commonly used tocolytics was performed to determine the probability of adverse events. Cost for an agent was determined by acquisition cost and the probability and cost of adverse events. A decision tree was constructed to determine which tocolytic had the lowest total costs, with subsequent sensitivity analysis.

RESULTS

A total of 19 clinical trials combined for a cohort of 1073 patients (indomethacin, 176 patients; magnesium sulfate, 451 patients; nifedipine, 176 patients; and terbutaline, 270 patients). The probability of adverse events was 57.9% for terbutaline, 22.0% for magnesium sulfate, 27.2% for nifedipine, and 11.4% for indomethacin. Nifedipine ($16.75) and indomethacin ($15.40) were the least expensive treatment options, compared with magnesium sulfate ($197.90) and terbutaline ($399.02) because of the cost of monitoring and treating adverse events.

CONCLUSION

If one elects a tocolytic, both nifedipine and indomethacin should be the agents of choice, based on a cost decision analysis.

The Evaluation of the Fetal Fibronectin Test for Prediction of Preterm Delivery in Symptomatic Patients

OBJECTIVE

This study was conducted to evaluate the usefulness of testing for fetal fibronectin (fFN) to rule out the diagnosis of preterm labour in symptomatic patients in a Canadian setting.

METHODS

This was a prospective, blinded clinical evaluation of fFN testing in women presenting with threatened preterm labour at between 24 and 34 weeks' gestation at two Canadian tertiary care centres.

RESULTS

Of the 149 women tested, 32 had a positive fFN test. In the total patient population, 10.1% delivered within seven days of testing, and 18.2% delivered prior to 34 weeks. A negative fFN result was associated with a 97.4% likelihood of delivering more than seven days after testing and with a 91.4% chance of delivering after 34 weeks.

CONCLUSION

The fFN test appears to provide useful information in the risk assessment of Canadian women presenting with symptoms compatible with preterm labour. A negative test has a high predictive value for delivering more than seven days after presentation.

Post-Cesarean Delivery Analgesia

Post-cesarean delivery pain relief is important. Good pain relief will improve mobility and can reduce the risk of thromboembolic disease, which is increased during pregnancy. Pain may also impair the mother's ability to optimally care for her infant in the immediate postpartum period and may adversely affect early interactions between mother and infant. Pain and anxiety may also reduce the ability of a mother to breast-feed effectively. It is necessary that pain relief be safe and effective, that it not interfere with the mother's ability to move around and care for her infant, and that it result in no adverse neonatal effects in breast-feeding women. The most commonly used modalities are systemic administration of opioids, either by intramuscular injection or i.v. by patient-controlled analgesia, and neuraxial injection of opioid as part of a regional anesthetic for cesarean delivery. These techniques have specific advantages and disadvantages which will be discussed in this review. In addition, there are new drug applications of potential benefit for the treatment of post-cesarean delivery pain.

Antiprostaglandin Drugs

Prostaglandins create conditions favorable for activation and stimulation of labor and are key components in the process of both normal and preterm labor. Antiprostaglandins may be useful in the prevention of preterm labor because they inhibit prostaglandin synthetase and reduce prostaglandin formation. The antiprostaglandin indomethacin has been the most studied as a tocolytic agent, but its success is limited because of fetal and neonatal complications associated with prolonged use. More recently, the cyclooxygenase-2 specific agents have been investigated because of their improved side effect profile. This article discusses the process of prostaglandin production and inhibition and reviews and critiques the available literature investigating the efficacy and safety of indomethacin and the newer cyclooxygenase-2 agents.

Magnesium Sulfate: The First-Line Tocolytic

Magnesium sulfate has become the first-line tocolytic for short-term use to arrest idiopathic preterm labor. The reasons for its acceptance include familiarity of the drug, ease of use, and the virtual absence of serious maternal side effects. Sufficient data exist showing its efficacy if used in higher doses. Attention to treating preterm labor has shifted to seeking answers about the fundamental causes. Gathering information about the specific causes and designing tailor-made treatment protocols for each of the numerous potential causes is essential. Scientifically sound research is needed to obtain answers about the important clinical questions surrounding magnesium sulfate.

Cyclo-oxygenase (COX) inhibitors for treating preterm labour

BACKGROUND

Preterm birth is a major cause of perinatal mortality and morbidity. Cyclo-oxygenase (COX) inhibitors inhibit uterine contractions, are easily administered and have fewer maternal side-effects compared to conventional tocolytics. However, adverse effects have been reported on the fetus and newborn as a result of exposure to COX inhibitors.

OBJECTIVES

To assess the effects on maternal, fetal and neonatal outcomes of COX inhibitors administered as a tocolytic agent to women in preterm labour when compared with (i) placebo or no intervention and (ii) other tocolytics. In addition, to compare the effects of non-selective COX inhibitors with COX-2 selective inhibitors.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's trials register (August 2004). We also contacted recognised experts and cross referenced relevant material.

SELECTION CRITERIA

All published and unpublished randomised trials in which COX inhibitors were used for tocolysis for women in labour between 20 and 36 completed weeks' gestation.

DATA COLLECTION AND ANALYSIS

Three authors independently evaluated methodological quality and extracted data. We sought additional information from trial authors.

MAIN RESULTS

This review includes outcome data from 13 trials with a total of 713 women. The non-selective COX inhibitor, indomethacin was used in 10 trials. When compared with placebo, COX inhibition (indomethacin only) resulted in a reduction in birth before 37 weeks' gestation (relative risk (RR) 0.21; one trial, 36 women), an increase in gestational age (weighted mean difference (WMD) 3.53 weeks) and birthweight (WMD 716.34 gm; two trials, 67 women). Compared to any other tocolytic, COX inhibition resulted in a reduction in birth before 37 weeks' gestation (RR 0.53; three trials, 168 women) and a reduction in maternal drug reaction requiring cessation of treatment (RR 0.07; five trials and 355 women). A comparison of non-selective COX inhibitors versus any COX-2 inhibitor (two trials, 54 women) did not demonstrate any differences in maternal or neonatal outcomes. Due to small numbers, all estimates of effect are imprecise and need to be interpreted with caution. Potential adverse effects of COX inhibition on the fetus, newborn or mother could not be adequately assessed due to insufficient data.

AUTHORS' CONCLUSIONS

There is insufficient information on which to base decisions about the role of COX inhibition for women in preterm labour. Further well designed trials are needed.

Tocolysis and preterm labour

PURPOSE OF REVIEW

There is persisting controversy about tocolytic treatment for preterm labour. This review addresses this controversy by appraising the recent clinical literature.

RECENT FINDINGS

Surveys of obstetricians indicate a high usage of tocolysis for preterm labour, but evidence that this treatment confers overall benefit is still lacking. Betamimetics are now, correctly, being abandoned in favour of nifedipine, which has superior tocolytic properties and better neonatal outcomes. There is no evidence of effectiveness for magnesium sulphate as a tocolytic. Atosiban is a newer agent, which appears to be effective in delaying preterm birth with a favourable maternal safety profile, but there are persisting concerns about the lack of impact on perinatal mortality and morbidity. Current research is addressing the COX-2 inhibitor, rofecoxib, which has theoretical advantages with respect to fetal safety.

SUMMARY

For the relatively small proportion of women in otherwise uncomplicated preterm labour prior to 34 weeks' gestation, there appears to be a place for short-term tocolysis to gain time so that corticosteroids can be administered to enhance fetal lung maturation and, if necessary, to transfer the woman to a facility with a neonatal intensive care unit. Nifedipine is an effective and cheap tocolytic agent. Atosiban appears to also be effective, but it is expensive and not universally available. Betamimetics and magnesium sulphate should be abandoned as tocolytic agents. There is a need for further clinical trials to establish an unequivocal evidence base for tocolysis, which requires placebo-controlled trials, and for comparative trials to identify the agent with superior characteristics.