Successful magnesium sulfate tocolysis: is "weaning" the drug necessary?

Antenatal magnesium sulphate and adverse neonatal outcomes: A systematic review and meta-analysis

BACKGROUND

There is widespread, increasing use of magnesium sulphate in obstetric practice for pre-eclampsia, eclampsia, and preterm fetal neuroprotection; benefit for preventing preterm labour and birth (tocolysis) is unproven. We conducted a systematic review and meta-analysis to assess whether antenatal magnesium sulphate is associated with unintended adverse neonatal outcomes.

METHODS AND FINDINGS

CINAHL, Cochrane Library, LILACS, MEDLINE, Embase, TOXLINE, and Web of Science, were searched (inceptions to 3 September 2019). Randomised, quasi-randomised, and non-randomised trials, cohort and case-control studies, and case reports assessing antenatal magnesium sulphate for pre-eclampsia, eclampsia, fetal neuroprotection, or tocolysis, compared with placebo/no treatment or a different magnesium sulphate regimen, were included. The primary outcome was perinatal death. Secondary outcomes included pre-specified and non-pre-specified adverse neonatal outcomes. Two reviewers screened 5,890 articles, extracted data, and assessed risk of bias following Cochrane Handbook and RTI Item Bank guidance. For randomised trials, pooled risk ratios (RRs) or mean differences, with 95% confidence intervals (CIs), were calculated using fixed- or random-effects meta-analysis. Non-randomised data were tabulated and narratively summarised. We included 197 studies (40 randomised trials, 138 non-randomised studies, and 19 case reports), of mixed quality. The 40 trials (randomising 19,265 women and their babies) were conducted from 1987 to 2018 across high- (16 trials) and low/middle-income countries (23 trials) (1 mixed). Indications included pre-eclampsia/eclampsia (24 trials), fetal neuroprotection (7 trials), and tocolysis (9 trials); 18 trials compared magnesium sulphate with placebo/no treatment, and 22 compared different regimens. For perinatal death, no clear difference in randomised trials was observed between magnesium sulphate and placebo/no treatment (RR 1.01; 95% CI 0.92 to 1.10; 8 trials, 13,654 babies), nor between regimens. Eleven of 138 non-randomised studies reported on perinatal death. Only 1 cohort (127 babies; moderate to high risk of bias) observed an increased risk of perinatal death with >48 versus ≤48 grams magnesium sulphate exposure for tocolysis. No clear secondary adverse neonatal outcomes were observed in randomised trials, and a very limited number of possible adverse outcomes warranting further consideration were identified in non-randomised studies. Where non-randomised studies observed possible harms, often no or few confounders were controlled for (moderate to high risk of bias), samples were small (200 babies or fewer), and/or results were from subgroup analyses. Limitations include missing data for important outcomes across most studies, heterogeneity of included studies, and inclusion of published data only.

CONCLUSIONS

Our findings do not support clear associations between antenatal magnesium sulphate for beneficial indications and adverse neonatal outcomes. Further large, high-quality studies (prospective cohorts or individual participant data meta-analyses) assessing specific outcomes, or the impact of regimen, pregnancy, or birth characteristics on these outcomes, would further inform safety recommendations. PROSPERO: CRD42013004451.

Antenatal exposure to indomethacin increases the risk of severe intraventricular hemorrhage, necrotizing enterocolitis, and periventricular leukomalacia: a systematic review with metaanalysis

OBJECTIVE

The purpose of this study was to provide an updated summary of the literature regarding the effects of tocolysis with indomethacin on neonatal outcome by systematically reviewing previously and recently reported data.

STUDY DESIGN

All previously reported studies pertaining to indomethacin tocolysis and neonatal outcomes along with recently reported data were identified with the use of electronic databases that had been supplemented with references that were cited in original studies and review articles. Observational studies that compared neonatal outcomes among preterm infants who were exposed and not exposed to indomethacin were included in this systematic review. Data were extracted and quantitative analyses were performed on those studies that assessed the neonatal outcomes of patients that received antenatal tocolysis with indomethacin.

RESULTS

Twenty-seven observational studies that met criteria for systematic review and metaanalysis were identified. These studies included 8454 infants, of whom 1731 were exposed to antenatal indomethacin and 6723 were not exposed. Relative risks with 95% confidence intervals were calculated for dichotomous outcomes with the use of random and fixed-effects models. Metaanalysis revealed no statistically significant differences in the rates of respiratory distress syndrome, patent ductus arteriosus, neonatal mortality rate, neonatal sepsis, bronchopulmonary dysplasia, or intraventricular hemorrhage (all grades). However, antenatal exposure to indomethacin was associated with an increased risk of severe intraventricular hemorrhage (grade III-IV based on Papile's criteria; relative risk, 1.29; 95% confidence interval, 1.06-1.56), necrotizing enterocolitis (relative risk, 1.36; 95% confidence interval, 1.08-1.71), and periventricular leukomalacia (relative risk, 1.59; 95% confidence interval, 1.17-2.17).

CONCLUSION

The use of indomethacin as a tocolytic agent for preterm labor is associated with an increased risk for severe intraventricular hemorrhage, necrotizing enterocolitis, and periventricular leukomalacia.

Amniotic Fluid Soluble Myeloid Differentiation-2 (sMD-2) as Regulator of Intra-amniotic Inflammation in Infection-induced Preterm Birth

PROBLEM

TLR4 mediates host responses to pathogens through a mechanism that involves protein myeloid differentiation-2 (MD-2) and its soluble form sMD-2. The role of sMD2 in intra-amniotic inflammation-induced preterm birth has not been previously explored.

METHOD OF STUDY

Human amniotic fluid (AF) sMD-2 was studied by Western blotting in 152 AF samples of patients who had an amniocentesis to rule-out infection (yes infection, n = 50; no infection, n = 50) or women with normal pregnancy outcome (second trimester genetic karyotyping, n = 26; third trimester lung maturity testing, n = 26). Histological localization and mRNA expression of MD2 in fetal membranes were studied by immunohistochemistry and RT-PCR. The ability of fetal membrane to release sMD-2 and inflammatory cytokines was studied in vitro.

RESULTS

Human AF contains three sMD-2 proteoforms whose levels of expression were lower at term. Intra-amniotic infection upregulated sMD-2. MD-2 mRNA and immunohistochemistry findings concurred. In vitro, LPS and monensin increased, while cycloheximide decreased sMD-2 production. Recombinant sMD-2 modulated TNF-α and IL-6 levels in a dose- and time-dependent fashion.

CONCLUSION

sMD2 proteoforms are constitutively present in human AF. The intensity of the intra-amniotic inflammatory response to bacteria or perhaps to other TLR4 ligands may be facilitated through synthesis and release of sMD2 by the amniochorion.

Transdermal nitroglycerin for the treatment of preterm labor: a systematic review and metaanalysis

OBJECTIVE

The purpose of this study was to evaluate the efficacy and safety of transdermal nitroglycerin as a tocolytic agent in women with preterm labor.

STUDY DESIGN

We conducted a systematic review and metaanalysis of randomized controlled trials.

RESULTS

Thirteen studies were included (1302 women) comparing transdermal nitroglycerin vs placebo (2 studies; n = 186); β2-adrenergic receptor agonists (9 studies; n = 1024); nifedipine (1 study; n = 50); and magnesium sulfate (1 study; n = 42). There were no significant differences between transdermal nitroglycerin and placebo for delivery within 48 hours of the initiation of treatment or at <28, <34, or <37 weeks of gestation, adverse neonatal outcomes, and neurodevelopmental status at 24 months of life. Nevertheless, 1 study found a marginally significant reduction in the risk of a composite outcome of major neonatal morbidity and perinatal death (3/74 [4.1%] vs 11/79 [13.9%]; relative risk, 0.29; 95% confidence interval, 0.08-1.00). When compared with β2-adrenergic receptor agonists, transdermal nitroglycerin was associated with a significant reduction in the risk of preterm birth at <34 and <37 weeks of gestation, admission to the neonatal intensive care unit, use of mechanical ventilation, and maternal side effects. There were no significant differences between transdermal nitroglycerin and nifedipine and magnesium sulfate in delivery within 48 hours of treatment and pregnancy prolongation, respectively. Overall, women who received transdermal nitroglycerin had a higher risk of headache.

CONCLUSION

Although transdermal nitroglycerin appears to be more effective than β2-adrenergic receptor agonists, the current evidence does not support its routine use as a tocolytic agent for the treatment of preterm labor. Further double-blind placebo-controlled trials are needed.

Magnesium maintenance therapy for preventing preterm birth after threatened preterm labour

BACKGROUND

Magnesium maintenance therapy is one of the types of tocolytic therapy used after an episode of threatened preterm labour (usually treated with an initial dose of tocolytic therapy) in an attempt to prevent the onset of further preterm contractions.

OBJECTIVES

To assess whether magnesium maintenance therapy is effective in preventing preterm birth after the initial threatened preterm labour is arrested.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2013).

SELECTION CRITERIA

Randomised controlled trials of magnesium therapy given to women after threatened preterm labour.

DATA COLLECTION AND ANALYSIS

The review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. We checked data entry.

MAIN RESULTS

We included four trials involving 422 women. Three trials had high risk of bias and none included any long-term follow-up of infants. No differences in the incidence of preterm birth or perinatal mortality were seen when magnesium maintenance therapy was compared with placebo or no treatment; or alternative therapies (ritodrine or terbutaline). The risk ratio (RR) for preterm birth (less than 37 weeks) for magnesium compared with placebo or no treatment was 1.05, 95% confidence interval (CI) 0.80 to 1.40 (two trials, 99 women); and 0.99, 95% CI 0.57 to 1.72 (two trials, 100 women) for magnesium compared with alternative therapies. The RR for perinatal mortality for magnesium compared with placebo or no treatment was 5.00, 95% CI 0.25 to 99.16 (one trial, 50 infants); and 5.00, 95% CI 0.25 to 99.16 (one trial, 50 infants) for magnesium compared with alternative treatments.Women taking magnesium preparations were less likely to report side effects (RR 0.67, 95% CI 0.47 to 0.96, three trials, 237 women), including palpitations or tachycardia (RR 0.26, 95% CI 0.13 to 0.52, three trials, 237 women) than women receiving alternative therapies. Women receiving magnesium were however, more likely to experience diarrhoea (RR 6.79, 95% CI 1.26 to 36.72, three trials, 237 women).

AUTHORS' CONCLUSIONS

There is not enough evidence to show any difference between magnesium maintenance therapy compared with either placebo or no treatment, or alternative therapies (ritodrine or terbutaline) in preventing preterm birth after an episode of threatened preterm labour.

Magnesium maintenance therapy for preventing preterm birth after threatened preterm labour

BACKGROUND

Magnesium maintenance therapy is one of the types of tocolytic therapy used after an episode of threatened preterm labour (usually treated with an initial dose of tocolytic therapy) in an attempt to prevent the onset of further preterm contractions.

OBJECTIVES

To assess whether magnesium maintenance therapy is effective in preventing preterm birth after the initial threatened preterm labour is arrested.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2010).

SELECTION CRITERIA

Randomised controlled trials of magnesium therapy given to women after threatened preterm labour.

DATA COLLECTION AND ANALYSIS

The review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. We checked data entry.

MAIN RESULTS

We included four trials, which recruited 422 women. Three trials had high risk of bias and none included any long-term follow up of infants. No differences in the incidence of preterm birth or perinatal mortality were seen when magnesium maintenance therapy was compared with placebo or no treatment; or alternative therapies (ritodrine or terbutaline). The risk ratio (RR) for preterm birth (less than 37 weeks) for magnesium compared with placebo or no treatment was 1.05, 95% confidence interval (CI) 0.80 to 1.40 (two trials, 99 women); and 0.99, 95% CI 0.57 to 1.72 (2 trials, 100 women) for magnesium compared with alternative therapies. The RR for perinatal mortality for magnesium compared with placebo or no treatment was 5.00, 95% CI 0.25 to 99.16 (one trial, 50 infants) and also compared with alternative treatments, was 5.00, 95% CI 0.25 to 99.16 (one trial, 50 infants). Women taking magnesium preparations were less likely to report palpitations or tachycardia than women receiving alternative therapies (RR 0.26, 95% CI 0.13 to 0.52, three trials, 237 women) but were much more likely to experience diarrhoea (RR 7.66, 95% CI 2.18 to 26.98, three trials, 237 women).

AUTHORS' CONCLUSIONS

There is not enough evidence to show any difference between magnesium maintenance therapy compared with either placebo or no treatment, or alternative therapies (ritodrine or terbutaline) in preventing preterm birth after an episode of threatened preterm labour.

Fetal heart rate monitoring patterns in women with amniotic fluid proteomic profiles indicative of inflammation

We hypothesized that abnormal fetal heart rate monitoring patterns (FHR-MPs) occur more often in pregnancies complicated by intra-amniotic inflammation. Therefore, our objective was to examine the relationships among FHR-MP abnormalities, intra-amniotic inflammation and/or infection, acute histological chorioamnionitis, and early-onset neonatal sepsis (EONS) in pregnancies complicated by preterm birth. Additionally, the ability of various FHR-MPs to predict EONS was investigated. FHR-MPs from 87 singleton premature neonates delivered within 48 hours from amniocentesis (gestational age, mean +/- SD: 28.9 +/- 3.3 weeks) were analyzed blindly using strict National Institute of Child Health and Human Development criteria. Strips were evaluated at three time points: at admission, at amniocentesis, and prior to delivery. Intra-amniotic inflammation was established based on a previously validated proteomic fingerprint (mass-restricted score). Diagnoses of histological chorioamnionitis and EONS were based on well-recognized pathological, clinical, and laboratory criteria. We determined that fetuses of women with severe intra-amniotic inflammation had a higher FHR baseline throughout the entire monitoring period and an increased frequency of a nonreactive FHR-MP at admission. Of all FHR-MPs, a nonreassuring test at admission had 32% sensitivity, 95% specificity, 73% positive predictive value, 77% negative predictive value, and 76% accuracy in predicting EONS. Although a nonreassuring FHR-MP at admission was significantly associated with EONS after correcting for gestational age (odds ratio, 5.6; 95% confidence interval, 1.2 to 26.2; P = 0.030), the majority of the neonates that developed EONS had an overall reassuring FHR-MP. Nonreassuring FHR-MPs at either amniocentesis or delivery had no association with EONS. We conclude that in cases complicated by preterm birth, a nonreassuring FHR-MP at the initial evaluation is a specific but not a sensitive predictor of EONS. An abnormal FHR-MP can thus raise the level of awareness that a fetus with EONS may be born, but it is not a useful clinical indicator of the need for antibiotic treatment of the neonate.

Value of placental microbial evaluation in diagnosing intra-amniotic infection

OBJECTIVE

To evaluate the ability of microbiologic and pathologic examination of the placenta to accurately diagnose intraamniotic infection and inflammation.

METHODS

One hundred eighty-three women with a clinically indicated amniocentesis were enrolled prospectively. We applied our analysis to 56 women with evidence of preterm labor or preterm premature rupture of membranes who delivered within 48 hours of amniotic fluid testing results. Twenty-three patients, assessed for fetal lung maturity in the third trimester, served as controls. Amniotic fluid was cultured for aerobic, anaerobic, Ureaplasma, and Mycoplasma species. We used mass spectrometry to assess the degree of intraamniotic inflammation (Mass Restricted scoring). After delivery, microbiologic and histologic studies of the placenta were performed. These results were interpreted in comparison with the direct microbiologic and inflammatory analysis of the amniotic fluid. A sample size of 45 patients was required to show a test accuracy of 80% or more.

RESULTS

Ninety-two percent of women with positive amniotic fluid cultures tested with at least one positive placenta culture. Eighty percent of women who had negative amniotic fluid cultures also tested with a positive placenta culture. The accuracy of placental cultures in predicting amniotic fluid infection varied from 44% to 57%. Placental pathology showed an accuracy of only 58% in diagnosing intraamniotic inflammation.

CONCLUSION

Placental microbiologic and histologic studies poorly reflect the infectious and inflammatory status of the amniotic fluid. Results of such studies should be interpreted with caution in the management and future counseling of women with preterm labor or preterm premature rupture of membranes.

LEVEL OF EVIDENCE

II.

Proteomic biomarkers of intra-amniotic inflammation: relationship with funisitis and early-onset sepsis in the premature neonate

Our goal was to determine the relationship between 4 amniotic fluid (AF) proteomic biomarkers (human neutrophil defensins 2 and 1, calgranulins C and A) characteristic of intra-amniotic inflammation, and funisitis and early-onset sepsis in premature neonates. The mass restricted (MR) score was generated from AF obtained from women in preterm labor (n = 123). The MR score ranged from 0-4 (none to all biomarkers present). Funisitis was graded histologically and interpreted in relation to the MR scores. Neonates (n = 97) were evaluated for early-onset sepsis. There was significant correlation between the severity of AF inflammation and the presence (53/123) and grades of funisitis (p < 0.001). Funisitis occurred independently of the amniocentesis-to-delivery interval or status of the membranes and was best predicted by an MR score 3-4 and an earlier gestational age (GA) at delivery. Neonates born to women with an MR score 3-4 had an increased incidence of suspected/confirmed sepsis, even after adjusting for GA at birth. Calgranulin C had the highest association with clinically significant funisitis, while calgranulin A had the strongest association with early-onset sepsis. To conclude, AF proteomic analysis shows that women with MR scores 3-4 are more likely to have histologic funisitis, and deliver neonates with early-onset sepsis.

The receptor for advanced glycation end products (RAGE) system in women with intraamniotic infection and inflammation

OBJECTIVE

Receptor for advanced glycation end products (RAGE) is a multiligand cell-surface receptor part of the immunoglobulin superfamily with crucial roles in inflammation. S100A12/ENRAGE, a biomarker of amniotic fluid (AF) inflammation, is a ligand for RAGE. sRAGE, a competitive soluble RAGE receptor, inhibits RAGE ligands. Here we aimed to investigate the presence and changes in components of the RAGE system in women with intra-amniotic infection and inflammation.

STUDY DESIGN

AF was retrieved by amniocentesis in 113 women stratified as follows: (1) positive AF culture (+AFC; GA = 27 [20-33] wk; n = 27); (2) negative AF culture (-AFC; GA = 30 [20-36] wk; n = 27); (3) second trimester control (2T-CRL; GA = 19 [15-25] wk; n = 31); (4) third trimester control (3T-CRL; GA = 36 [31-38] wk; n = 28). We used mass spectrometry (SELDI) to detect S100A12/ENRAGE in AF. sRAGE levels were measured using specific immunoassays. Placental pathology was interpreted in relationship to the presence or absence of histologic acute inflammation and immunoreactivity of S100A12/ENRAGE and RAGE. mRNA expression of S100A12/ENRAGE, sRAGE, and RAGE in amniochorion and placental villous tissue was investigated using quantitative real-time polymerase chain reaction (PCR).

RESULTS

Presence of the S100A12/ENRAGE biomarker SELDI peak was confirmed in 70% of the +AFC but in only 10% of the -AFC samples (P < .001). The inflammatory biomarker was absent in all control samples. We further determined that the competitive inhibitor sRAGE is temporally regulated during gestation and that its AF levels are not influenced by the presence of either intra-amniotic infection or inflammation. Histologic choriamnionitis associated with intense staining for S100A12/ENRAGE, particularly in inflammatory cells. The immunoreactivity for extracellular domain of RAGE was localized exclusively to amnion epithelial, decidual, and extravillous trophoblast cells. Yet, acute histologic chorioamnionitis was related to increased gene expression of S100A12/ENRAGE in fetal membranes and decreased sRAGE and RAGE in the placenta.

CONCLUSION

The S100A12/ENRAGE system is markedly upregulated in women with intra-amniotic infection and correlates with the degree of inflammation. Further studies remain to elucidate whether the gestational age dependence of the inhibitor molecule sRAGE may explain the higher incidence of infection-related preterm deliveries and especially rupture of the membranes at earlier gestational age.

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.

Treatment of preterm labor

The ultimate goal of treating preterm labor is to prolong the pregnancy long enough to decrease the incidence of neonatal mortality and morbidity associated with prematurity, while minimizing maternal and fetal risks. There are many controversies in treating preterm labor. Much of this controversy stems from the difficulty in establishing efficacy and safety of interventions and uncertainty of the diagnosis of preterm labor. This article outlines conventional measures and tocolytic therapy directed at prolonging the pregnancy. A review of the effect of tocolytic agents, administration, side effects, and nursing interventions is included. Key words: preterm labor treatment,

Magnesium as part of balanced general anaesthesia with propofol, remifentanil and mivacurium: a double-blind, randomized prospective study in 50 patients

BACKGROUND AND OBJECTIVE

To test the hypothesis that magnesium sulphate reduces the amount of remifentanil needed for general anaesthesia in combination with propofol and mivacurium, we studied 50 patients undergoing elective pars plana vitrectomy in a double-blind, randomized prospective fashion.

METHODS

Magnesium sulphate (50 mg kg(-1) body weight) or placebo (equal volume of NaCl) was given slowly intravenously after induction of anaesthesia with propofol 1-2 mg kg(-1). Anaesthesia was maintained with propofol (using electroencephalographic control), mivacurium (according to train-of-four monitoring of neuromuscular blockade) and remifentanil (according to heart rate and arterial pressure).

RESULTS

We observed a significant reduction in remifentanil consumption from 0.14 to 0.09 microg kg(-1) min(-1) (P < 0.01). Mivacurium consumption was also markedly reduced from 0.01 to 0.008 mg kg(-1) min(-1) (P < 0.01), whereas propofol consumption remained unchanged. There was a trend towards lower postoperative pain scores, less pain medication requirements in 24 h after surgery and less postoperative nausea and vomiting in the magnesium group but not statistically significant. No side-effects were observed.

CONCLUSION

We can recommend the use of magnesium sulphate as a safe and cost-effective supplement to a general anaesthetic regimen with propofol, remifentanil and mivacurium, although we cannot clearly distinguish between a mechanism as a (co)analgesic agent at the NMDA-receptor site or its properties as a sympatholytic. The effect of a single bolus dose of 50 mg kg(-1) on induction lasts for about 2 h. For longer cases, either a continuous infusion or repeated bolus doses might be necessary.

Magnesium for preventing preterm birth after threatened preterm labour

BACKGROUND

Magnesium therapy is sometimes continued after an episode of threatened preterm labour in an attempt to prevent the onset of further preterm contractions.

OBJECTIVES

The objective of this review was to assess the effects of magnesium maintenance therapy on preventing preterm birth after threatened preterm labour.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register.

SELECTION CRITERIA

Randomised controlled trials of magnesium therapy given to women after threatened preterm labour.

DATA COLLECTION AND ANALYSIS

Trial quality assessment and data extraction were done independently by two reviewers.

MAIN RESULTS

Two trials were included. Both were of poor quality and neither study included any long-term follow up of infants. The incidence of preterm birth or perinatal mortality was not reduced by magnesium maintenance therapy compared to alternative therapy or no treatment.

REVIEWER'S CONCLUSIONS

There is not enough evidence to show that magnesium maintenance therapy is effective in preventing preterm birth after an episode of threatened preterm labour.

Controversies in tocolytic therapy

In general, tocolytic agents are effective in stopping uterine contractions and in temporarily delaying delivery. The benefit of stopping uterine contractions is dependent on the fetal status and gestational age. The rationale for stopping preterm labor is to improve neonatal outcome. At this time, the best way to improve neonatal outcome would be to assure delivery in a center capable of caring for a preterm infant and prescription of glucocorticoids to decrease the risk of respiratory distress syndrome and other neonatal complications. Intravenous tocolysis for premature labor has found a prominent place in the obstetrician's armamentarium. We recommend the use of magnesium sulfate as first-line therapy. When comparing maternal and fetal risks, side effects, and the safety profile, magnesium sulfate is superior to beta-mimetics; however, there are still significant problems with potential morbidity and mortality for both mother and fetus with any tocolytics. Adjunctive use of indomethacin with magnesium sulfate may be used through 32 weeks for up to 48 hours at a time. Most tocolytics are effective in stopping labor for 48-72 hours. None have been shown to decrease the rate of preterm delivery. Once the uterus is quiescent and intravenous tocolytics are stopped, prolonged use of tocolytics has not been shown to be effective in preventing preterm birth. Tocolytics have significant long-term side effects to the mother's cardiovascular system, carbohydrate metabolism, and the fetal cardiovascular system. Thus, the prolonged use of prophylactic tocolytics after cessation of intravenous medications is not recommended. Tocolytics may be an appropriate therapy during preterm labor vaginal bleeding, ruptured membranes, multiple gestation, or advanced cervical dilatation. In all situations, however, careful guidelines must be observed. These guidelines include: (1) maternal and fetal well-being must be established before tocolytic therapy; (2) causes of preterm labor should be evaluated and treated when possible; (3) the risk/benefit ratio for both the mother and fetus must be re-evaluated on an ongoing basis; (4) when tocolytics are given before pulmonary maturity, then antenatal corticosteroids also should be considered in every case; (5) long-term use of tocolytics is difficult to justify at this time; (6) the safest tocolytic should be used for the shortest amount of time possible. It is doubtful, because of the nature of tocolytics, that newer tocolytics will be developed that will eliminate the problems of preterm delivery. Preterm delivery is an end-stage symptom of a multifactorial disease. Preterm labor is one of the last symptoms in a cascade of biochemical events that lead to preterm delivery. The most appropriate way to end preterm delivery would be to prevent the causes that initiate the cascade that ends in preterm labor. Authors' Note: Literally hundreds of papers have been written in the last 30 years on tocoloysis. For the purposes of space, when studies are summarized in peer-reviewed articles, we have referenced the reviews instead of the individual studies.

Recent advances in the therapeutic management of preterm labour

Preterm labour and delivery pose an increasing problem to the obstetrician. Improvements in tocolysis with the recent introduction of new therapeutic targeting strategies, and a reappraisal of the safety and relative efficacy of some older compounds, have led to a tendency away from prescribing beta-sympathomimetic agents. Infection prophylaxis and promotion of fetal lung maturity are deemed advantageous, but treatment protocols have not been clarified. This review examines the important publications of the past year in these areas.