Beta-mimetics in preterm labour: an overview of the randomized controlled trials

A novel technique for prediction of preterm birth: fetal nasal flow Doppler

OBJECTIVES

Absence of fetal breathing movements (FBM) has been found to be a good predictor of preterm delivery in symptomatic patients. However, analysis of FBM patterns and Doppler measurement of them for preterm birth prediction have not been performed before. In this study, we aimed to investigate and analyze FBM patterns in symptomatic preterm labor patients by fetal ultrasonography and nasal Doppler.

METHODS

This was a multicenter, prospective cohort study. Singleton pregnant patients between 24 and 37 gestational weeks diagnosed with preterm labor were included in the study. Patients were evaluated in three groups: no FBM (Group 1), regular FBM (Group 2), irregular FBM (Group3).

RESULTS

Seventy-three patients were available for the final analysis after exclusion. Preterm delivery rate in 24 h in groups were 91.7, 32.7 and 100%, respectively. The absence of FBM (Group 1) was statistically significant for preterm delivery in for both 24 (91.7 vs. 42.6%, p=0.002) and 48 h (91.7 vs. 49.2%, p=0.006) when compared with fetal breathing positive Group 2 and 3. In fetal nasal Doppler analyses in Group 2, the inspiration/expiration number rate was significantly lower in the patients who delivered in 24 h (0.98±0.2 vs. 1.25±0.57, p=0.015). By using fetal nasal Doppler, combination of absence of FBM or irregular FBM or regular FBM with inspiration number/expiration number (I/E) <1.25 detects 94.6% of patients who will eventually deliver in the first 24 h after admission.

CONCLUSIONS

Examining FBM patterns and using nasal Doppler may help the clinician to differentiate those who will deliver preterm and may be an invaluable tool for managing preterm labor patients.

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.

Tocolysis: A Review of the Literature

Importance

Preterm delivery represents an important cause of infant morbidity and mortality. Various tocolytics have been studied with the objective of stopping preterm labor, increasing gestational age at delivery, and preventing complications related to preterm birth.

Objective

This review aims to summarize the major classes of tocolytics and review the evidence regarding use of each.

Evidence Acquisition

A PubMed search of the following terms was performed to gather relevant data: "tocolytic," "preterm labor," "preterm delivery," "PPROM," "magnesium," "indomethacin," "nifedipine," and "betamimetics."

Results

The benefits and risks of nonsteroid anti-inflammatory drugs, calcium channel blockers, magnesium, and betamimetics are reviewed. Calcium channel blockers afford superior outcomes in terms of prolonging gestation and decreasing neonatal morbidity and mortality with the fewest adverse effects.

Conclusions and Relevance

Tocolytics, particularly calcium channel blockers, may provide benefit to pregnant women and their infants. Their use should be tailored to the particular clinical circumstances of the patient and used in conjunction with other management strategies (e.g., administration of corticosteroids for fetal lung maturation or magnesium for neuroprotection and transfer to a tertiary medical center). Further research and professional guidelines are needed on optimal use of these agents.

Association between Beta-Sympathomimetic Tocolysis and Risk of Autistic Spectrum Disorders, Behavioural and Developmental Outcome in Toddlers

AIM

To investigate whether maternal intravenous beta-mimetic tocolytic therapy increases the risk of autistic spectrum disorders (ASD) and poorer behavioural and developmental outcomes.

METHOD

Our study is a prospective case-control study among 90 children between 1.5 and three years old. Cases (n = 46) were toddlers with betamimetic tocolytic exposure; control group toddlers (n = 44) were tocolytic untreated. Treated and untreated groups were also divided into subgroups: term and preterm delivered. The gestational age of tocolytic treatment start, the dose and duration of exposure in hours were obtained from obstetric medical records. The Brief Infant-Toddler Social and Emotional Assessment (BITSEA), the Modified Checklist for Autism in Toddlers (M-CHAT) and the Denver Developmental Screening Test (DDST) tests were applied for evaluation of social, emotional problems, autism and developmental disorders.

RESULTS

Term and preterm born toddlers treated tocolytically in utero didn't demonstrate a higher risk of autistic disorders or poorer behavioural and developmental results than controls. In the preterm group, the earliest start of tocolytic treatment was correlated with toddlers lower score of the Competencies Scale (p = 0.009) and a higher score of the Problems Scale (p = 0.048). Also, we concluded that preterm membrane rupture was associated with higher ASD risk in the untreated group (p = 0.043).

CONCLUSION

Exposure to betamimetics during pregnancy was not associated with an increased risk of autism, behavioural and developmental disorders.

Evaluating the teratogenicity of the selective ß3-adrenoceptor agonist, CL 316.243 hydrate by employing FETAX (frog embryo teratogenesis assay)

In this study, the frog embryo teratogenesis assay (FETAX - Xenopus) technique was employed to evaluate the potential teratogenicity of the selective ß-adrenoceptor (AR) agonist, CL 316.243. In this context, CL 316.243 was applied to the South African clawed frog (Xenopus laevis) embryos. The media containing the CL 316.24-exposed embryos were monitored and changed/replaced once every 24 hours. Using FETAX, we determined the minimum concentrations to inhibit growth (MCIG) for CL 316.243. The 96-hour no observable adverse effect concentration (NOAEC), the 96-hour lowest observable adverse effect concentration (LOAEC), the 96-hour EC₅₀ (malformation) and the 96-hour LC₅₀ (lethal concentration) for mortality and malformation could not be determined because the used concentrations did not affect viability or the presence of abnormalities. On the other hand, the MCIG of CL 316.243 was determined as 1 mg/L. Our results demonstrated that CL 316.243 administration was associated with no of teratogenic and toxic effects. However, from first concentration we used (1 to 5 mg/L) length of embryos reduced significantly (p < 0.001) when compared to control of Xenopus embryos. Further studies should be conducted with different concentrations in order to investigate the optimal concentrations for treating preterm labor with these substances.

Interleukin 6 and fetal fibronectin as a predictors of preterm delivery in symptomatic patients

Preterm delivery is the leading cause of neonatal mortality and morbidity. The rate of preterm births has been estimated to be about 15 million, which accounts for 11.1% of all live births worldwide. The purpose of this study was to evaluate the cervico-vaginal (CVF) cytokine IL-6 and fetal fibronectin (fFN) status as predictors of preterm delivery in patients with symptoms of preterm labor. Patients with symptoms suggestive of preterm labor were recruited from September 2013 to March 2014. Vaginal swabs were taken for fetal fibronectin test (fFN) and CVF IL-6. Antibiotics, steroids and tocolytics were administered, where appropriate. The outcome was measured by the occurrence of preterm delivery within 14 days from the day of hospital admission. Cut-off value of 1305 pg/mL for the concentration of IL-6 in the CVF was the best predictor of preterm delivery, with the sensitivity of 69.4% and specificity of 68.2%. Patients with positive fFN test had the OR of 6.429 (95%CI 1.991-20.758) to deliver prematurely. The multivariate analysis of combined fFN and CVF IL-6 tests resulted in risk of 86.7% to deliver prematurely, if both tests were positive. The combination of both tests performed better than the individual tests and decreased the false positive rate, which in turn reduced the chances for inappropriate patient treatment, bringing down the costs.

Oxytocin receptor antagonists for inhibiting preterm labour

BACKGROUND

Preterm birth, defined as birth between 20 and 36 completed weeks, is a major contributor to perinatal morbidity and mortality globally. Oxytocin receptor antagonists (ORA), such as atosiban, have been specially developed for the treatment of preterm labour. ORA have been proposed as effective tocolytic agents for women in preterm labour to prolong pregnancy with fewer side effects than other tocolytic agents.

OBJECTIVES

To assess the effects on maternal, fetal and neonatal outcomes of tocolysis with ORA for women with preterm labour compared with placebo or any other tocolytic agent.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 December 2013).

SELECTION CRITERIA

We included all randomised controlled trials (published and unpublished) of ORA for tocolysis of labour between 20 and 36 completed weeks' gestation.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated methodological quality and extracted trial data. When required, we sought additional data from trial authors. Results are presented as risk ratio (RR) for categorical and mean difference (MD) for continuous data with the 95% confidence intervals (CI). Where appropriate, the number needed to treat for benefit (NNTB) and the number needed to treat for harm (NNTH) were calculated.

MAIN RESULTS

This review update includes eight additional studies (790 women), giving a total of 14 studies involving 2485 women.Four studies (854 women) compared ORA (three used atosiban and one barusiban) with placebo. Three studies were considered at low risk of bias in general (blinded allocation to treatment and intervention), the fourth study did not adequately blind the intervention. No difference was shown in birth less than 48 hours after trial entry (average RR 1.05, 95% CI 0.15 to 7.43; random-effects, (two studies, 152 women), perinatal mortality (RR 2.25, 95% CI 0.79 to 6.38; two studies, 729 infants), or major neonatal morbidity. ORA (atosiban) resulted in a small reduction in birthweight (MD -138.86 g, 95% CI -250.53 to -27.18; two studies with 676 infants). In one study, atosiban resulted in an increase in extremely preterm birth (before 28 weeks' gestation) (RR 3.11, 95% CI 1.02 to 9.51; NNTH 31, 95% CI 8 to 3188) and infant deaths (up to 12 months) (RR 6.13, 95% CI 1.38 to 27.13; NNTH 28, 95% CI 6 to 377). However, this finding may be confounded due to randomisation of more women with pregnancy less than 26 weeks' gestation to atosiban. ORA also resulted in an increase in maternal adverse drug reactions requiring cessation of treatment in comparison with placebo (RR 4.02, 95% CI 2.05 to 7.85; NNTH 12, 95% CI 5 to 33). No differences were shown in preterm birth less than 37 weeks' gestation or any other adverse neonatal outcomes. No differences were evident by type of ORA, although data were limited.Eight studies (1402 women) compared ORA (atosiban only) with betamimetics; four were considered of low risk of bias (blinded allocation to treatment and to intervention). No statistically significant difference was shown in birth less than 48 hours after trial entry (RR 0.89, 95% CI 0.66 to 1.22; eight studies with 1389 women), very preterm birth (RR 1.70, 95% CI 0.89 to 3.23; one study with 145 women), extremely preterm birth (RR 0.84, 95% CI 0.37 to 1.92; one study with 244 women) or perinatal mortality (RR 0.55, 95% CI 0.21 to 1.48; three studies with 816 infants). One study (80 women), of unclear methodological quality, showed an increase in the interval between trial entry and birth (MD 22.90 days, 95% CI 18.03 to 27.77). No difference was shown in any reported measures of major neonatal morbidity (although numbers were small). ORA (atosiban) resulted in less maternal adverse effects requiring cessation of treatment (RR 0.05, 95% CI 0.02 to 0.11; NNTB 6, 95% CI 6 to 6; five studies with 1161 women).Two studies including (225 women) compared ORA (atosiban) with calcium channel blockers (CCB) (nifedipine only). The studies were considered as having high risk of bias as neither study blinded the intervention and in one study it was not known if allocation was blinded. No difference was shown in birth less than 48 hours after trial entry (average RR 1.09, 95% CI 0.44 to 2.73, random-effects; two studies, 225 women) and extremely preterm birth (RR 2.14, 95% CI 0.20 to 23.11; one study, 145 women). No data were available for the outcome of perinatal mortality. One small trial (145 women), which did not employ blinding of the intervention, showed an increase in the number of preterm births (before 37 weeks' gestation) (RR 1.56, 95% CI 1.13 to 2.14; NNTH 5, 95% CI 3 to 19), a lower gestational age at birth (MD -1.20 weeks, 95% CI -2.15 to -0.25) and an increase in admission to neonatal intensive care unit (RR 1.70, 95% CI 1.17 to 2.47; NNTH 5, 95% CI 3 to 20). ORA (atosiban) resulted in less maternal adverse effects (RR 0.38, 95% CI 0.21 to 0.68; NNTB 6, 95% CI 5 to 12; two studies, 225 women) but not maternal adverse effects requiring cessation of treatment (RR 0.36, 95% CI 0.01 to 8.62; one study, 145 women). No longer-term outcome data were included.

AUTHORS' CONCLUSIONS

This review did not demonstrate superiority of ORA (largely atosiban) as a tocolytic agent compared with placebo, betamimetics or CCB (largely nifedipine) in terms of pregnancy prolongation or neonatal outcomes, although ORA was associated with less maternal adverse effects than treatment with the CCB or betamimetics. The finding of an increase in infant deaths and more births before completion of 28 weeks of gestation in one placebo-controlled study warrants caution. However, the number of women enrolled at very low gestations was small. Due to limitations of small numbers studied and methodological quality, further well-designed randomised controlled trials are needed. Further comparisons of ORA versus CCB (which has a better side-effect profile than betamimetics) are needed. Consideration of further placebo-controlled studies seems warranted. Future studies of tocolytic agents should measure all important short- and long-term outcomes for women and infants, and costs.

Betamimetics for inhibiting preterm labour

BACKGROUND

Preterm birth is a major contributor to perinatal mortality and morbidity worldwide. Tocolytic agents are drugs used to inhibit uterine contractions. Betamimetics are tocolytic agents that have been widely used, especially in resource-poor countries.

OBJECTIVES

To assess the effects of betamimetics given to women with preterm labour.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 December 2013) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials of betamimetics, administered by any route or any dose, in the treatment of women in preterm labour where betamimetics were compared with other betamimetics, placebo or no treatment.

DATA COLLECTION AND ANALYSIS

Two review authors assessed risk of bias and extracted the data independently.

MAIN RESULTS

Twenty-eight trials were assessed as eligible for inclusion in the review, but eight did not report any outcome data relevant to the review. Results are based on the 20 trials that contributed data.Twelve trials, involving 1367 women, compared betamimetics with placebo. Betamimetics decreased the number of women in preterm labour giving birth within 48 hours (average risk ratio (RR) 0.68, 95% confidence interval (CI) 0.53 to 0.88, 10 trials, 1209 women). There was a decrease in the number of births within seven days (average RR 0.80; 95% CI 0.65 to 0.98, five trials, 911 women) but there was no evidence of a reduction in preterm birth (before 37 weeks' gestation) (RR 0.95; 95% CI 0.88 to 1.03, 10 trials, 1212 women). No benefit was demonstrated for betamimetics for perinatal death (RR 0.84; 95% CI 0.46 to 1.55, 11 trials, 1332 infants), or neonatal death (RR 0.90; 95% CI 0.27 to 3.00, six trials, 1174 infants). No significant effect was demonstrated for respiratory distress syndrome (RR 0.87; 95% CI 0.71 to 1.08, eight trials, 1239 infants). A few trials reported on cerebral palsy, infant death and necrotising enterocolitis; no significant differences between groups were identified for any of these outcomes. Betamimetics were significantly associated with the following outcomes: withdrawal from treatment due to adverse effects; maternal chest pain; dyspnoea; palpitation; tremor; headaches; hypokalaemia; hyperglycaemia; nausea or vomiting; nasal stuffiness; and fetal tachycardia.Nine trials compared different types of betamimetics. Other betamimetics were compared with ritodrine in five trials (n = 948). Other comparisons were examined in single trials: hexoprenaline compared with salbutamol (n = 140), slow versus moderate release salbutamol (n = 52) and salbutamol compared with terbutaline (n = 200). Trials were small, varied, and of insufficient quality to delineate any consistent patterns of effect.

AUTHORS' CONCLUSIONS

Betamimetics help to delay birth, which may give time to allow women to be transferred to tertiary care or to complete a course of antenatal corticosteroids. However, multiple adverse effects must be considered. The data are too few to support the use of any particular betamimetic.

The short-term prediction of preterm birth: a systematic review and diagnostic metaanalysis

OBJECTIVE

To assess the diagnostic accuracy of fetal fibronectin (fFN), fetal breathing movements (FBM), and cervical length (CL) for the short-term prediction of preterm birth in symptomatic patients.

STUDY DESIGN

Diagnostic metaanalysis using bivariate methods.

RESULTS

Pooled sensitivities for fFN, FBM, and CL for delivery within 48 hours of testing were 0.62 (95% confidence interval [CI], 0.43-0.78), 0.75 (95% CI, 0.57-0.87) and 0.77 (95% CI, 0.54-0.90), respectively. Pooled specificities for fFN, FBM, and CL for delivery within 48 hours were 0.81 (95% CI, 0.74-0.86), 0.93 (95% CI, 0.75-0.98) and 0.88 (95% CI, 0.84-0.91). Pooled sensitivities for fFN, FBM, and CL for delivery within 7 days were 0.75 (95% CI, 0.69-0.80), 0.67 (95% CI, 0.43-0.84), and 0.74 (95% CI, 0.58-0.85). Pooled specificities for fFN, FBM, and CL for delivery within 7 days were 0.79 (95% CI, 0.76-0.83), 0.98 (95% CI, 0.83-1.00) and 0.89 (95% CI, 0.85-0.92). Based on a pretest probability of 10% for delivery within 48 hours, posttest probabilities (positive and negative) were 27% and 5% for fFN, 54% and 3% for fFN, and 42% and 3% for CL. For a pretest probability of 20% for delivery within 7 days, posttest probabilities (positive and negative) were 48% and 7% for fFN, 89% and 8% for FBM, and 63% and 7% for CL.

CONCLUSION

In symptomatic patients, for fFN, absence of FBM, and CL have diagnostic use as predictors of delivery within 48 hours and within 7 days of testing. Absence of FBM appears to be the best test for predicting preterm birth.

Automated conduction velocity analysis in the electrohysterogram for prediction of imminent delivery: a preliminary study

Background. Analysis of the electrohysterogram (EHG) is a promising diagnostic tool for preterm delivery. For the introduction in the clinical practice, analysis of the EHG should be reliable and automated to guarantee reproducibility. Study Goal. Investigating the feasibility of automated analysis of the EHG conduction velocity (CV) for detecting imminent delivery. Materials and Methods. Twenty-two patients presenting with uterine contractions (7 preterm) were included. An EHG was obtained noninvasively using a 64-channel high-density electrode grid. Contractions were selected based on the estimated intrauterine pressure derived from the EHG, the tocodynamometer, and maternal perception. Within the selected contractions, the CV vector was identified in two dimensions. Results. Nine patients delivered within 24 hours and were classified as a labor group. 64 contractions were analyzed; the average amplitude of the CV vector was significantly higher for the labor group, 8.65 cm/s ± 1.90, compared to the nonlabor group, 5.30 cm/s ± 1.47 (P < 0.01). Conclusion. The amplitude of the CV is a promising parameter for predicting imminent (preterm) delivery. Automated estimation of this parameter from the EHG signal is feasible and should be regarded as an important prerequisite for future clinical studies and applications.

Maintenance therapy with oxytocin antagonists for inhibiting preterm birth after threatened preterm labour

BACKGROUND

In some women, an episode of preterm labour settles and does not result in immediate preterm birth. Subsequent treatment with tocolytic agents such as oxytocin receptor antagonists may then have the potential to prevent the recurrence of preterm labour, prolonging gestation, and preventing the adverse consequences of prematurity for the infant.

OBJECTIVES

To assess the effects of maintenance therapy with oxytocin antagonists administered by any route after an episode of preterm labour in order to delay or prevent preterm birth.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 July 2013), sought ongoing and unpublished trials by contacting experts in the field and searched the reference lists of relevant articles.

SELECTION CRITERIA

Randomised controlled trials comparing oxytocin antagonists with any alternative tocolytic agent, placebo or no treatment, used for maintenance therapy after an episode of preterm labour.

DATA COLLECTION AND ANALYSIS

We used the standard methods of The Cochrane Collaboration and the Cochrane Pregnancy and Childbirth Group. Two review authors independently undertook evaluation of methodological quality and extracted trial data.

MAIN RESULTS

This review includes one trial of 513 women. When compared with placebo, atosiban did not reduce preterm birth before 37 weeks (risk ratio (RR) 0.89; 95% confidence intervals (CI) 0.71 to 1.12), 32 weeks (RR 0.85; 95% CI 0.47 to 1.55), or 28 weeks (RR 0.75; 95% CI 0.28 to 2.01). No difference was shown in neonatal morbidity, or perinatal mortality.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support the use of oxytocin receptor antagonists to inhibit preterm birth after a period of threatened or actual preterm labour. Any future trials using oxytocin antagonists or other drugs as maintenance therapy for preventing preterm birth should examine a variety of important infant outcome measures, including reduction of neonatal morbidity and mortality, and long-term infant follow-up. Future research should also focus on the pathophysiological pathways that precede preterm labour.

Oral betamimetics for maintenance therapy after threatened preterm labour

BACKGROUND

Some women who have threatened to give birth prematurely, subsequently settle. They may then take oral tocolytic maintenance therapy to prevent preterm birth and to prolong gestation.

OBJECTIVES

To assess the effects of oral betamimetic maintenance therapy after threatened preterm labour for preventing preterm birth.

SEARCH METHODS

We updated the search of the Cochrane Pregnancy and Childbirth Group's Trials Register on 9 November 2012.

SELECTION CRITERIA

Randomised controlled trials comparing oral betamimetic with alternative tocolytic therapy, placebo or no therapy, for maintenance following treatment of threatened preterm labour.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the selection criteria and carried out data extraction and quality assessment of studies.

MAIN RESULTS

We did not identify any new trials from the updated search so the results remain unchanged as follows.We included 13 randomised controlled trials (RCTs) with a total of 1551 women. We found no differences for admission to the neonatal intensive care unit when betamimetics were compared with placebo (risk ratio (RR) 1.28, 95% confidence interval (CI) 0.68 to 2.41; two RCTs of terbutaline with 2600 women) or with magnesium (RR 0.80, 95% CI 0.43 to 1.46; one RCT of 137 women). The rate of preterm birth (less than 37 weeks) showed no significant difference in six RCTs, four comparing ritodrine with placebo/no treatment and two comparing terbutaline with placebo/no treatment (RR 1.11, 95% CI 0.91 to 1.35; 644 women). We observed no differences between betamimetics and placebo, no treatment or other tocolytics for perinatal mortality and morbidity outcomes. Some adverse effects such as tachycardia were more frequent in the betamimetics groups than the groups allocated to placebo, no treatment or another type of tocolytic.

AUTHORS' CONCLUSIONS

Available evidence does not support the use of oral betamimetics for maintenance therapy after threatened preterm labour.

Effectiveness of terbutaline pump for the prevention of preterm birth. A systematic review and meta-analysis

BACKGROUND

Subcutaneous terbutaline (SQ terbutaline) infusion by pump is used in pregnant women as a prolonged (beyond 48-72 h) maintenance tocolytic following acute treatment of preterm contractions. The effectiveness and safety of this maintenance tocolysis have not been clearly established. We aimed to systematically evaluate the effectiveness and safety of subcutaneous (SQ) terbutaline infusion by pump for maintenance tocolysis.

METHODOLOGY/PRINCIPAL FINDINGS

MEDLINE, EMBASE, CINAHL, the Cochrane Library, the Centre for Reviews and Dissemination databases, post-marketing surveillance data and grey literature were searched up to April 2011 for relevant experimental and observational studies. Two randomized trials, one nonrandomized trial, and 11 observational studies met inclusion criteria. Non-comparative studies were considered only for pump-related harms. We excluded case-reports but sought FDA summaries of post-marketing surveillance data. Non-English records without an English abstract were excluded. Evidence of low strength from observational studies with risk of bias favored SQ terbutaline pump for the outcomes of delivery at <32 and <37 weeks, mean days of pregnancy prolongation, and neonatal death. Observational studies of medium to high risk of bias also demonstrated benefit for other surrogate outcomes, such as birthweight and neonatal intensive care unit (NICU) admission. Several cases of maternal deaths and maternal cardiovascular events have been reported in patients receiving terbutaline tocolysis.

CONCLUSIONS/SIGNIFICANCE

Although evidence suggests that pump therapy may be beneficial as maintenance tocolysis, our confidence in its validity and reproducibility is low, suggesting that its use should be limited to the research setting. Concerns regarding safety of therapy persist.

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.

Progesterone effects on preterm birth in high-risk pregnancies: a randomized placebo-controlled trial

PURPOSE

The purpose of this study was to evaluate whether the prophylactic administration of vaginal progesterone would reduce the preterm birth rate in high-risk population including singleton and twin pregnancies.

METHODS

This was a randomized, double blind, placebo-controlled study that included 150 high-risk pregnancies. Risk groups included prior spontaneous preterm birth, twin pregnancy, and uterine malformation. Micronized progesterone or placebo (100 mg) was administered daily by vaginal suppository between 24 and 34 weeks of gestation. We compared progesterone and placebo groups for incidence of preterm labor and preterm delivery. Data were compared by χ² analysis and Fisher exact test.

RESULTS

There was a statistically significant difference in the rate of preterm labor between placebo and progesterone groups (45.7 vs. 25%, respectively; p < 0.05). More women delivered before 37 weeks in placebo group (57.2%) than in progesterone group (40%; p < 0.05). Administering progesterone also reduced the preterm birth before 34 weeks of gestation. The difference between placebo and progesterone group was statistically significant (24.3 vs. 8.8%; p < 0.05). However, there was no significant difference in neonatal death between placebo and progesterone groups.

CONCLUSION

Prophylactic vaginal progesterone reduced the rate of preterm labor and preterm delivery in high-risk pregnancies.

Efficacy of aggressive tocolysis for preterm labor with advanced cervical dilatation

OBJECTIVE

Study the effectiveness of tocolysis for preterm labor with advanced cervical dilatation ( > or = 3 cm) to achieve sufficient latency for the effect of steroids to occur, and delivery of more mature neonates.

STUDY DESIGN

We studied 249 singleton pregnancies, 23-36 weeks gestation in preterm labor, stratified by weeks of gestation and degree of cervical dilatation (Group A: 117, < 3 cm; Group B: 132, 3 cm) who were given tocolysis and compared for the length of latency and neonatal outcome.

RESULTS

Maternal characteristics were similar between groups except African-American women were admitted with more advanced cervical dilatation. Latency 72 hours was achieved in Group A: > 75% at all gestational ages, and Group B: > 50%. Latency > or = 72 hours, according to the degree of cervical dilatation, was for Group A: 90%, for Group B: 50-75% from > 3-5 cm dilatation, and 40% at 5.1-6 cm dilatation. Neonatal morbidity was mild with a decreased risk of long-term disability.

CONCLUSIONS

Aggressive tocolytic therapy for preterm labor with advanced cervical dilatation is efficacious, allows for steroid therapy, and allows delivery of more mature neonates.

Terbutaline inhibits corticotropin-releasing hormone (CRH) expression in human trophoblast cells

OBJECTIVE

To evaluate the effect of beta-adrenergic agonists on the regulation of the expression of the placental corticotropin-releasing hormone (CRH) gene.

STUDY DESIGN

Term placentae were collected at the time of elective cesarean section, and trophoblast cells were harvested, isolated, and cultured. The isolated trophoblasts were plated, cultured and subsequently treated with cortisol, terbutaline, RU486, or vehicle control. CRH expression, mRNA abundance of CRH, and the housekeeping gene beta-actin were evaluated by Northern blot analysis.

RESULTS

Exposure of the trophoblasts to terbutaline (10(-8) M) inhibited the expression of the CRH gene as depicted by Northern blot analysis. Co-addition of terbutaline (10(-8) M) and RU486 (10(-6) M) did not block the stimulatory effects of RU486 on placental trophoblast cells.

CONCLUSION

The beta-adrenergic agonist terbutaline inhibits the expression of CRH in human trophoblasts. This finding may provide insight into the mechanism of action of terbutaline as a tocolytic agent.

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.

Obstetric disorders in the ICU

Obstetric disorders account for 55% to 80% of admissions to the intensive care unit in the obstetric population. Medical conditions are emerging as the leading cause of maternal mortality, partly because of marked improvement in surgical and obstetric care in the developed world. The rise in maternal mortality related to medical conditions can be explained by multiple factors: improved medical care, women with chronic illnesses reaching childbearing years, older age at time of first pregnancy, improved reproductive technologies, and severe medical conditions exacerbated by the physiologic changes of pregnancy. This article reviews obstetric disorders leading to intensive care unit admissions.

Maintenance therapy with oxytocin antagonists for inhibiting preterm birth after threatened preterm labour

BACKGROUND

In some women, an episode of preterm labour settles and does not result in immediate preterm birth. Subsequent treatment with tocolytic agents such as oxytocin receptor antagonists may then have the potential to prevent the recurrence of preterm labour, prolonging gestation, and preventing the adverse consequences of prematurity for the infant.

OBJECTIVES

To assess the effects of maintenance therapy with oxytocin antagonists administered by any route after an episode of preterm labour in order to delay or prevent preterm birth.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2008), sought ongoing and unpublished trials by contacting experts in the field and searched the reference lists of relevant articles.

SELECTION CRITERIA

Randomised controlled trials comparing oxytocin antagonists with any alternative tocolytic agent, placebo or no treatment, used for maintenance therapy after an episode of preterm labour.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Collaboration and the Cochrane Pregnancy and Childbirth Group were used. Two review authors independently undertook evaluation of methodological quality and extracted trial data.

MAIN RESULTS

This review includes one trial of 513 women. When compared with placebo, atosiban did not reduce preterm birth before 37 weeks (risk risk (RR) 0.89; 95% confidence intervals (CI) 0.71 to 1.12), 32 weeks (RR 0.85; 95% CI 0.47 to 1.55), or 28 weeks (RR 0.75; 95% CI 0.28 to 2.01). No difference was shown in neonatal morbidity, or perinatal mortality.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support the use of oxytocin receptor antagonists to inhibit preterm birth after a period of threatened or actual preterm labour. Any future trials using oxytocin antagonists or other drugs as maintenance therapy for preventing preterm birth should examine a variety of important infant outcome measures, including reduction of neonatal morbidity and mortality, and long-term infant follow up. Future research should also focus on the pathophysiological pathways that precede preterm labour.

Prevention of preterm birth

For an infant without lethal congenital malformations there is no risk greater than to be born too early. In addition, preterm birth with its many consequences may compromise the life of the whole family. Thus, prevention of preterm birth is one of the greatest challenges in obstetrics. However, this has proven to be difficult. This difficulty is in part due to the fact that, although we know a large number of clinical factors which are know a large number of clinical factors which are associated with preterm birth, the final mechanisms triggering the onset of preterm contractions or premature rupture of the fetal membranes (PROM) have remained largely unclear. We review the prevention of preterm birth in the light of the newest data; an interested reader is also referred to other recent overviews on the same topic.

Can myometrial electrical activity identify patients in preterm labor?

OBJECTIVE

The objective of the study was to determine whether myometrial electrical activity can differentiate false from true preterm labor.

STUDY DESIGN

Electrical uterine myography (EUM) was measured prospectively on 87 women, gestational age less than 35 weeks. The period between contractions, power of contraction peaks and movement of center of electrical activity (RMS), was used to develop an index score (1-5) for prediction of preterm delivery (PTD) within 14 days of the test. The score was compared with fetal fibronectin (fFN) and cervical length (CL).

RESULTS

Patients delivering within 14 days from testing showed a higher index and mean RMS (P = .000). No patients with EUM index scores of 1-2 delivered in this time frame. Combining EUM with CL or fFN increased predictability. Logistic regression revealed that history of PTD and EUM index had 4- to 5-fold increased risk for PTD. Gestational age at testing, body mass index, fFN, and CL were nonsignificant contributors to PTD risk.

CONCLUSION

Measuring myometrial electrical activity may enhance identification of patients in true premature labor.

Two different treatment regimens in women with preterm contractions who were admitted to a hospital due to a presumptive diagnosis of preterm labor: an observational study

AIM

To determine the effect of adherence to a set of clinical practice guidelines (CPG) for the management of preterm contractions on health-care resource consumption and pregnancy outcomes.

METHODS

This prospective observational study was conducted in a tertiary care university hospital from January 2003 to December 2004. Comparisons were made between the cases receiving treatment according to the CPG (CPG group) and those receiving treatment deviating from the CPG (non-CPG group).

RESULTS

There were 203 patients with preterm contractions. Compared with the CPG group, the non-CPG group had a higher rate of both tocolytic and steroid use, a longer maternal hospital stay, and a lower neonatal birthweight.

CONCLUSIONS

Adherence to CPG in patients with preterm contractions at 28(+0)-36(+6) weeks' gestation consumes fewer health-care resources without compromising pregnancy outcomes.

Cervical phosphorylated insulin-like growth factor binding protein-1 in prediction of preterm delivery

BACKGROUND

The aim of this study was to evaluate the phosphorylated isoform of insulin-like growth factor binding protein-1 (phIGFBP-1) in endocervical secretions as a predictor of preterm delivery in symptomatic and asymptomatic pregnant women.

METHODS

The study included 105 patients between 24 and 34 weeks' gestation with uterine contractions and 73 controls. Ph IGFBP-1 in cervical secretions was assessed in all patients by using a qualitative, immunochromatographic one-step dipstick test. Data analysis included Student's test, Chi-Square, Fisher's exact test and Kruskal Wallis variance analysis.

RESULTS

Preterm birth rate was 19.04% (20/105) in the study group. Of the 25 patients with a positive phIGFBP-1 test, mean gestational age at delivery was 32.8+/-3.8, whereas of the 80 patients with a negative phIGFBP-1 test mean gestational age at delivery was 37.8+/-2.5, in the study group (P<0.05). The sensitivity, specificity, positive predictive value and negative predictive value for phIGFBP-1 in symptomatic patients were 70, 87.05, 56 and 92.5%, respectively, while in asymptomatic patients they were 40, 82.35, 14.28 and 94.91%, respectively.

CONCLUSIONS

The phIGFBP-1 in cervical secretions is a potential specific marker for preterm delivery occurring before 37 weeks. Also cervical detection of phIGFBP-1 by immunochromatography is a rapid and easily applicable test that highly predicts preterm delivery.

A step-by-step diagnosis of exclusion in a twin pregnancy with acute respiratory failure due to non-fatal amniotic fluid embolism: a case report

INTRODUCTION

Respiratory failure may develop during the later stages of pregnancy and is usually associated with tocolysis or other co-existing conditions such as pneumonia, sepsis, pre-eclampsia or amniotic fluid embolism syndrome.

CASE PRESENTATION

We present the case of a 34-year-old healthy woman with a twin pregnancy at 31 weeks and 6 days who experienced acute respiratory failure, a few hours after administration of tocolysis (ritodrine), due to preterm premature rupture of the membranes. Her chest discomfort was significantly ameliorated after the ritodrine infusion was stopped and a Cesarean section was performed 48 hours later under spinal anesthesia; however, 2 hours after surgery she developed severe hypoxemia, hypotension, fever and mild coagulopathy. The patient was intubated and transferred to the intensive care unit where she made a quick and uneventful recovery within 3 days. As there was no evidence for drug- or infection-related thromboembolic or myocardial causes of respiratory failure, we conclude that our patient experienced a rare type of non-fatal amniotic fluid embolism.

CONCLUSION

In spite of the lack of solid scientific support for our diagnosis, we conclude that our patient suffered an uncommon type of amniotic fluid embolism syndrome and we believe that this report highlights the need for extreme vigilance and a high index of suspicion for such a diagnosis in any pregnant individual.

Support vector machine for SAR/QSAR of phenethyl-amines

AIM

To discriminate 32 phenethyl-amines between antagonists and agonists, and predict the activities of these compounds.

METHODS

The support vector machine (SVM) is employed to investigate the structure-activity relationship (SAR)/quantitative structure-activity relationship (QSAR) of phenethyl-amines based on molecular descriptors.

RESULTS

By using the leave-one-out cross-validation (LOOCV) test, 1 optimal SAR and 2 optimal QSAR models for agonists and antagonists were attained. The accuracy of prediction for the classification of phenethyl-amines by using the LOOCV test is 91.67%, and the accuracy of prediction for the classification of phenethyl-amines by using the independent test is 100%; the results are better than those of the Fisher, the artificial neural network (ANN), and the K-nearest neighbor models for this real world data. The RMSE (root mean square error) of antagonists' QSAR model is 0.5881, and the RMSE of agonists' QSAR model is 0.4779, which are better than those of the multiple linear regression, partial least squares, and ANN models for this real world data.

CONCLUSION

The SVM can be used to investigate the SAR and QSAR of phenethylamines and could be a promising tool in the field of SAR/QSAR research.

The effects and selectivity of beta-adrenoceptor agonists in rat myometrium and urinary bladder

Recent evidence supports a role for beta(3)-adrenoceptors in human non-pregnant and pregnant myometrium. The present study was designed to characterize the pharmacology of beta-adrenoceptors involved in the function of non-pregnant rat myometrium by comparison of the activity of several beta-adrenoceptor agonists and antagonists in isolated rat uterus and urinary bladder. Contractions of myometrial and detrusor strips were induced by adding 1 nM oxytocin and 15 mM KCl respectively. Cumulative concentration-response curves to the selective beta(3)-adrenoceptor agonists, CL 316243 and BRL 37344 and the selective beta(2)-adrenoceptor agonist ritodrine were obtained in the presence and absence of the selective beta(2)-adrenoceptor antagonist ICI 118551 and the non-selective beta-adrenoceptor antagonist bupranolol. Both BRL 37344 (pD(2)=6.79+/-0.09) and ritodrine (pD(2)=6.89+/-0.19) produced potent inhibition of oxytocin-induced contractions in myometrial strips; CL 316243 was inactive at concentrations up to 10 microM. Concentration effect curves to both BRL 37344 and ritodrine were shifted (10 to 30-fold) to the right in the presence of ICI 118551 (10 nM). BRL 37344 (pD(2)=8.51+/-0.21) and CL 316243 (pD(2)=8.61+/-0.24) produced potent inhibition of detrusor strips, while ritodrine was almost 100-fold less potent (pD(2)=5.83+/-0.17). The response to all agonists was significantly attenuated by pretreatment with bupranolol (10 microM), but only ritodrine was affected by ICI 118551 (1 microM). These results demonstrate that relaxation of rat myometrium is mediated by beta(2)-adrenoceptors while, consistent with previous reports, the beta(3)-subtype is primarily responsible for relaxation of rat detrusor.