Magnesium sulphate for pre-eclampsia and eclampsia: the evidence so far

Alternative magnesium sulphate regimens for women with pre-eclampsia and eclampsia

BACKGROUND

Magnesium sulphate is the drug of choice for the prevention and treatment of women with eclampsia. Regimens for administration of this drug have evolved over the years, but there is no clarity on the comparative benefits or harm of alternative regimens. This is an update of a review first published in 2010.

OBJECTIVES

To assess if one magnesium sulphate regimen is better than another when used for the care of women with pre-eclampsia or eclampsia, or both, to reduce the risk of severe morbidity and mortality for the woman and her baby.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (29 April 2022), and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised trials and cluster-randomised trials comparing different regimens for administration of magnesium sulphate used in women with pre-eclampsia or eclampsia, or both. Comparisons included different dose regimens, intramuscular versus intravenous route for maintenance therapy, and different durations of therapy. We excluded studies with quasi-random or cross-over designs. We included abstracts of conference proceedings if compliant with the trustworthiness assessment.

DATA COLLECTION AND ANALYSIS

For this update, two review authors assessed trials for inclusion, performed risk of bias assessment, and extracted data. We checked data for accuracy. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

For this update, a total of 16 trials (3020 women) met our inclusion criteria: four trials (409 women) compared regimens for women with eclampsia, and 12 trials (2611 women) compared regimens for women with pre-eclampsia. Most of the included trials had small sample sizes and were conducted in low- and middle-income countries. Eleven trials reported adequate randomisation and allocation concealment. Blinding of participants and clinicians was not possible in most trials. The included studies were for the most part at low risk of attrition and reporting bias. Treatment of women with eclampsia (four comparisons) One trial compared a loading dose-alone regimen with a loading dose plus maintenance dose regimen (80 women). It is uncertain whether either regimen has an effect on the risk of recurrence of convulsions or maternal death (very low-certainty evidence). One trial compared a lower-dose regimen with standard-dose regimen over 24 hours (72 women). It is uncertain whether either regimen has an effect on the risk of recurrence of convulsion, severe morbidity, perinatal death, or maternal death (very low-certainty evidence). One trial (137 women) compared intravenous (IV) versus standard intramuscular (IM) maintenance regimen. It is uncertain whether either route has an effect on recurrence of convulsions, death of the baby before discharge (stillbirth and neonatal death), or maternal death (very low-certainty evidence). One trial (120 women) compared a short maintenance regimen with a standard (24 hours after birth) maintenance regimen. It is uncertain whether the duration of the maintenance regimen has an effect on recurrence of convulsions, severe morbidity, or side effects such as nausea and respiratory failure. A short maintenance regimen may reduce the risk of flushing when compared to a standard 24 hours maintenance regimen (risk ratio (RR) 0.27, 95% confidence interval (CI) 0.08 to 0.93; 1 trial, 120 women; low-certainty evidence). Many of our prespecified critical outcomes were not reported in the included trials. Prevention of eclampsia for women with pre-eclampsia (five comparisons) Two trials (462 women) compared loading dose alone with loading dose plus maintenance therapy. Low-certainty evidence suggests an uncertain effect with either regimen on the risk of eclampsia (RR 2.00, 95% CI 0.61 to 6.54; 2 trials, 462 women) or perinatal death (RR 0.50, 95% CI 0.19 to 1.36; 2 trials, 462 women). One small trial (17 women) compared an IV versus IM maintenance regimen for 24 hours. It is uncertain whether IV or IM maintenance regimen has an effect on eclampsia or stillbirth (very low-certainty evidence). Four trials (1713 women) compared short postpartum maintenance regimens with continuing for 24 hours after birth. Low-certainty evidence suggests there may be a wide range of benefit or harm between groups regarding eclampsia (RR 1.99, 95% CI 0.18 to 21.87; 4 trials, 1713 women). Low-certainty evidence suggests there may be little or no effect on severe morbidity (RR 0.96, 95% CI 0.71 to 1.29; 2 trials, 1233 women) or side effects such as respiratory depression (RR 0.80, 95% CI 0.25 to 2.61; 2 trials, 1424 women). Three trials (185 women) compared a higher-dose maintenance regimen versus a lower-dose maintenance regimen. It is uncertain whether either regimen has an effect on eclampsia (very low-certainty evidence). Low-certainty evidence suggests that a higher-dose maintenance regimen has little or no effect on side effects when compared to a lower-dose regimen (RR 0.79, 95% CI 0.61 to 1.01; 1 trial 62 women). One trial (200 women) compared a maintenance regimen by continuous infusion versus a serial IV bolus regimen. It is uncertain whether the duration of the maintenance regimen has an effect on eclampsia, side effects, perinatal death, maternal death, or other neonatal morbidity (very low-certainty evidence). Many of our prespecified critical outcomes were not reported in the included trials.

AUTHORS' CONCLUSIONS

Despite the number of trials evaluating various magnesium sulphate regimens for eclampsia prophylaxis and treatment, there is still no compelling evidence that one particular regimen is more effective than another. Well-designed randomised controlled trials are needed to answer this question.

Magnesium sulphate and other anticonvulsants for women with pre-eclampsia

BACKGROUND

Eclampsia, the occurrence of a seizure (fit) in association with pre-eclampsia, is rare but potentially life-threatening. Magnesium sulphate is the drug of choice for treating eclampsia. This review assesses its use for preventing eclampsia.

OBJECTIVES

To assess the effects of magnesium sulphate, and other anticonvulsants, for prevention of eclampsia.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (4 June 2010), and the Cochrane Central Register of Controlled Trials Register (The Cochrane Library 2010, Issue 3).

SELECTION CRITERIA

Randomised trials comparing anticonvulsants with placebo or no anticonvulsant, or comparisons of different drugs, for pre-eclampsia.

DATA COLLECTION AND ANALYSIS

Two authors assessed trial quality and extracted data independently.

MAIN RESULTS

We included 15 trials. Six (11,444 women) compared magnesium sulphate with placebo or no anticonvulsant: magnesium sulphate more than a halved the risk of eclampsia (risk ratio (RR) 0.41, 95% confidence interval (CI) 0.29 to 0.58; number needed to treat for an additional beneficial outcome (NNTB) 100, 95% CI 50 to 100), with a non-significant reduction in maternal death (RR 0.54, 95% CI 0.26 to 1.10) but no clear difference in serious maternal morbidity (RR 1.08, 95% CI 0.89 to 1.32). It reduced the risk of placental abruption (RR 0.64, 95% CI 0.50 to 0.83; NNTB 100, 95% CI 50 to 1000), and increased caesarean section (RR 1.05, 95% CI 1.01 to 1.10). There was no clear difference in stillbirth or neonatal death (RR 1.04, 95% CI 0.93 to 1.15). Side effects, primarily flushing, were more common with magnesium sulphate (24% versus 5%; RR 5.26, 95% CI 4.59 to 6.03; number need to treat for an additional harmful outcome (NNTH) 6, 95% CI 5 to 6).Follow-up was reported by one trial comparing magnesium sulphate with placebo: for 3375 women there was no clear difference in death (RR 1.79, 95% CI 0.71 to 4.53) or morbidity potentially related to pre-eclampsia (RR 0.84, 95% CI 0.55 to 1.26) (median follow-up 26 months); for 3283 children exposed in utero there was no clear difference in death (RR 1.02, 95% CI 0.57 to 1.84) or neurosensory disability (RR 0.77, 95% CI 0.38 to 1.58) at age 18 months.Magnesium sulphate reduced eclampsia compared to phenytoin (three trials, 2291 women; RR 0.08, 95% CI 0.01 to 0.60) and nimodipine (one trial, 1650 women; RR 0.33, 95% CI 0.14 to 0.77).

AUTHORS' CONCLUSIONS

Magnesium sulphate more than halves the risk of eclampsia, and probably reduces maternal death. There is no clear effect on outcome after discharge from hospital. A quarter of women report side effects with magnesium sulphate.

Alternative magnesium sulphate regimens for women with pre-eclampsia and eclampsia

BACKGROUND

Magnesium sulphate remains the drug of choice for both prevention and treatment of women with eclampsia. Regimens for administration of this drug have evolved over the years, but have not yet been formally evaluated.

OBJECTIVES

To assess the comparative effects of alternative regimens for the administration of magnesium sulphate when used for the care of women with pre-eclampsia or eclampsia, or both.

SEARCH STRATEGY

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

SELECTION CRITERIA

Randomised trials comparing different regimens for administration of magnesium sulphate used for the care of women with pre-eclampsia or eclampsia, or both.

DATA COLLECTION AND ANALYSIS

All four review authors assessed trial quality and extracted data independently.

MAIN RESULTS

We identified 17 studies of which six (866 women) met the inclusion criteria: two trials (451 women) compared regimens for women with eclampsia and four (415 women) for women with pre-eclampsia.Treatment of eclampsia: one trial compared loading dose alone with loading dose plus maintenance therapy for 24 hours (401 women). There was no clear difference between the groups in the risk ratio (RR) of recurrence of convulsions (RR 1.13, 95% confidence interval (CI) 0.42 to 3.05) or stillbirth (RR 1.13, 95% CI 0.66 to 1.92), and the CIs are wide. One trial compared a low dose regimen with a standard dose regimen over 24 hours (50 women). This study was too small for any reliable conclusions about the comparative effects.Prevention of eclampsia: one trial compared intravenous with intramuscular maintenance regimen for 24 hours (17 women). This trial was too small for any reliable conclusions. Three trials compared short maintenance regimens postpartum with continuing for 24 hours after the birth (398 women), even taken together these trials were too small for any reliable conclusions.

AUTHORS' CONCLUSIONS

Although strong evidence supports the use of magnesium sulphate for prevention and treatment of eclampsia, trials comparing alternative treatment regimens are too small for reliable conclusions.

Neurologic aspects of eclampsia

Eclampsia continues to be a significant cause of maternal and fetal death throughout the world. Neurologists have a specific role to play in the diagnosis and management of patients who have eclampsia, especially those who have recurrent seizures, raised intracranial pressure, and coma. Postpartum patients may be admitted to a neurology service when they present to the emergency department with seizures. The cornerstone of treatment has been blood pressure control and magnesium sulfate with its antivasospastic effect. Should this fail, antiepileptic drugs of proved efficacy, such as diazepam and phenytoin, can be used. Recent studies reveal genetic and mitochondrial defects in eclampsia, but further investigation is warranted to determine the complex underlying pathophysiologic interplay and the optimum prophylactic and therapeutic management.

Magnesium sulphate and other anticonvulsants for women with pre-eclampsia

BACKGROUND

Pre-eclampsia is a relatively common complication of pregnancy. Eclampsia, the occurrence of one or more convulsions (fits) in association with the syndrome of pre-eclampsia, is a rare but serious complication. Anticonvulsants are used in the belief they help prevent eclamptic fits and so improve outcome.

OBJECTIVES

The objective was to assess the effects of anticonvulsants for pre-eclampsia on the women and their children.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (28 November 2002), and the Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 2002).

SELECTION CRITERIA

Randomised trials comparing anticonvulsants with placebo or no anticonvulsants or comparisons of different anticonvulsants in women with pre-eclampsia.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed trial quality and extracted data independently.

MAIN RESULTS

Six trials (11,444 women) compared magnesium sulphate with placebo or no anticonvulsant. There was more than a halving in the risk of eclampsia associated with magnesium sulphate (relative risk (RR) 0.41, 95% confidence interval (CI) 0.29 to 0.58; number needed to treat (NNT) 100, 95% CI 50 to 100). The risk of dying was non-significantly reduced by 46% for women allocated magnesium sulphate (RR 0.54, 95% CI 0.26 to 1.10). For serious maternal morbidity RR 1.08, 95% CI 0.89 to 1.32. Side effects were more common with magnesium sulphate (24% versus 5%; RR 5.26, 95% CI 4.59 to 6.03; NNT for harm 6, 95% CI 6 to 5). The main side effect was flushing. Risk of placental abruption was reduced for women allocated magnesium sulphate (RR 0.64, 95% CI 0.50 to 0.83; NNT 100, 95% CI 50 to 1000). Women allocated magnesium sulphate had a small increase (5%) in the risk of caesarean section (95% CI 1% to 10%). There was no overall difference in the risk of stillbirth or neonatal death (RR 1.04, 95% CI 0.93 to 1.15). Magnesium sulphate was better than phenytoin for reducing the risk of eclampsia (two trials 2241 women; RR 0.05, 95% CI 0.00 to 0.84), but with an increased risk of caesarean section (RR 1.21, 95% CI 1.05 to 1.41). It was also better than nimodipine (1 trial, 1650 women; RR 0.33, 95% CI 0.14 to 0.77).

REVIEWER'S CONCLUSIONS

Magnesium sulphate more than halves the risk of eclampsia, and probably reduces the risk of maternal death. It does not improve outcome for the baby, in the short term. A quarter of women have side effects, particularly flushing.

Loading dose versus standard regime of magnesium sulfate in the management of eclampsia: a randomized trial

OBJECTIVE

To determine whether only loading dose of magnesium sulfate is effective in controlling convulsion in eclampsia.

STUDY METHODS

This prospective study was conducted in Dhaka Medical College and Hospital, Bangladesh between July and November 1999. Eclamptic patients who were eligible for magnesium sulfate (MgSO4) therapy were randomly assigned by lottery to receive either only loading dose (n = 202) or standard regime (n = 199) of MgSO4. Besides the anticonvulsant, patients of both the groups were managed by same protocol for eclampsia management prepared by Eclampsia Working Group, Bangladesh. Efficacy of both the regimes was assessed by measuring the rate of recurrent convulsion. Results were expressed as mean +/- SD and a proportion. Statistical analysis was done using unpaired t-test, Z-test and chi2 test as appropriate. A P-value of < 0.05 was considered significant.

RESULTS

At the time of randomization there were no significant differences between the two groups in terms of age (22.40 +/- 4.21 vs 22.49 +/- 4.67 years), parity (72.77% vs 70.35% primi), type of eclampsia (84.65% vs 85.42% antepartum eclampsia), number of convulsions (5.30 +/- 3.26 vs 5.48 +/- 3.32 times), gestational age (35.65 +/- 3.37 vs 35.13 +/- 3.26 weeks), systolic blood pressure (153.19 +/- 20.19 vs 154.17 +/- 22.32 mmHg), diastolic blood pressure (106.23 +/- 13.84 vs 105.60 +/- 12.88 mmHg), proteinuria (70.80% vs 72.36% had > + proteinuria) and Glasgow Coma Scale (GCS) (73.26% vs 75.88% > 8) for the loading and standard regime groups. There were also no differences between the two groups in mean fit and treatment interval (6.88 +/- 5.26 vs 7.12 +/- 4.29h), fit and delivery interval (11.35 +/- 10.22 vs 11 +/- 6.69h) and return of consciousness (10.94 +/- 8.29 vs 11.24 +/- 8.37h). The recurrent convulsion rate was almost the same in both the groups (3.96% in loading vs 3.51% in standard regime, P > 0.05). Case fatality rate was 4.45% and 5.02% in loading and standard regime groups, respectively (P > 0.05).

CONCLUSION

Only loading dose of MgSO4 can control convulsion in eclampsia and it is as effective as standard regime.

Is the prophylactic administration of magnesium sulphate in women with pre-eclampsia indicated prior to labour?

OBJECTIVE

To determine whether prophylactic magnesium sulphate is necessary to prevent eclampsia and associated complications among women with pre-eclampsia prior to labour.

DESIGN

Case series.

SETTING

Tertiary referral centre.

POPULATION

Three hundred and eighteen women with pre-eclampsia (blood pressure > or = 140/90 mmHg and > or = 2+ proteinuria) who were not in labour or for planned induction thereof and had not received magnesium sulphate during transfer.

METHODS

Clinical evaluation of the pregnant women with careful blood pressure control. Magnesium sulphate was withheld even in the presence of imminent eclampsia. During labour, the option of magnesium sulphate prophylaxis was left to the clinician, but magnesium sulphate was administered in cases of eclampsia.

MAIN OUTCOME MEASURES

Eclampsia and related complications.

RESULTS

Five women (1.5%) developed eclampsia, although none developed related complications. Women presented at an early gestational age (mean 30 weeks), with high blood pressure, often suffering from headaches. Twenty pregnancies were terminated prior to viability, of which half were terminated for maternal reasons. Ten intrauterine deaths occurred. Most often fetal distress (38.6%) initiated the delivery process, which was mainly by caesarean section (68.5%). With the exception of epigastric discomfort, symptoms and signs of imminent eclampsia decreased after admission. Blood pressure values were significantly lower at delivery although biochemistry results deteriorated from admission to delivery.

CONCLUSION

In women with pre-eclampsia prior to labour, where blood pressure control was carefully applied but magnesium sulphate not given, the eclampsia rate was low and eclampsia did not appear to worsen the existing prognosis for mother or fetus.

Oral beta-blockers for mild to moderate hypertension during pregnancy

BACKGROUND

Hypertension is a common complication of pregnancy. Antihypertensive drugs are widely used in the belief these will improve outcome for both the woman (such as decreasing the risk of stroke or eclampsia) and her baby (such as decreasing the risk of preterm birth and its complications). Beta-blockers are a popular choice of antihypertensive agent during pregnancy; other choices include methyldopa and calcium channel blockers.

OBJECTIVES

The aim of this review is to assess whether oral beta-blockers are overall better than placebo, or no beta-blocker, for women with mild-moderate hypertension during pregnancy, and to assess whether oral beta-blockers have any advantages over other antihypertensive agents for women with mild-moderate hypertension during pregnancy. Both maternal outcomes (e.g., the incidence of severe hypertension) and perinatal outcomes (e.g., mortality) were of interest.

SEARCH STRATEGY

Register of trials maintained by the Cochrane Pregnancy and Childbirth Group, MEDLINE 1966-97, bibliographies of retrieved papers, personal files. Date of last search: June 2000.

SELECTION CRITERIA

Trials comparing beta-blockers with (i) placebo or no therapy, or (ii) other antihypertensive agents, for women with mild-moderate pregnancy hypertension (i.e., blood pressure under 170 mm Hg systolic, or 110 mm Hg diastolic).

DATA COLLECTION AND ANALYSIS

All data were extracted independently by two investigators, who were not blinded to outcome or other trial characteristics. Whenever possible, missing data were obtained by personal communication with authors. Discrepancies were resolved by discussion. The overview was divided into two comparisons: (i) beta-blockers versus placebo or no therapy, and (ii) beta-blockers versus other antihypertensives.

MAIN RESULTS

Twenty-seven trials, involving just under 2400 women, are included in this review. Fourteen trials (1516 women) compared beta-blockers with placebo/no beta blocker. Oral beta-blockers decrease the risk of severe hypertension (relative risk (RR) 0.37, 95% confidence interval (CI) 0.26-0.53) and the need for additional antihypertensive drugs (RR 0.44, 95% CI 0.31-0.62). There are insufficient data for any conclusions about the effect on perinatal mortality or preterm delivery. Beta-blockers seem to be associated with an increase in small for gestational age infants (RR 1.34, 95% CI 1.01-1.79). Maternal hospital admission may be decreased, neonatal bradycardia increased and respiratory distress syndrome decreased, but these outcomes are only reported in a very small proportion of trials. Eleven trials (787 women) compared beta-blockers with methyldopa. Beta-blockers appear to be no more effective and probably equally as safe (from maternal and perinatal perspectives) as methyldopa. Single small trials have compared beta-blockers with hydralazine and with nicardipine. It is unusual for women to change drugs due to side effects.

REVIEWER'S CONCLUSIONS

The improvement in control of maternal blood pressure with use of beta-blockers would be worthwhile only if it were reflected in other more substantive benefits for the mother and/or baby, and none have yet been clearly demonstrated. The effect of beta-blockers on perinatal outcome is uncertain, given that the worrying trend to an increase in small for gestational age infants is partly dependent on one small outlying trial. Large, randomised controlled trials are needed to determine whether antihypertensive therapy in general (rather than beta-blocker therapy specifically) results in benefits that outweigh the risks for treatment of mild-moderate pregnancy hypertension. If so, then it would be appropriate to look at which antihypertensive is best. Beta-blockers would remain a candidate class of agents.

A randomised controlled trial of intravenous magnesium sulphate versus placebo in the management of women with severe pre-eclampsia

OBJECTIVE

To determine whether the administration of prophylactic intravenous magnesium sulphate reduces the occurrence of eclampsia in women with severe pre-eclampsia.

DESIGN

Randomised controlled trial.

SETTING

A tertiary referral obstetric unit.

POPULATION

Eight hundred and twenty-two women with severe pre-eclampsia requiring termination of pregnancy by induction of labour or caesarean section.

METHODS

The women were randomised to receive either placebo (saline) or magnesium sulphate intravenously. The investigators were blinded to the contents of the pre-mixed solutions.

MAIN OUTCOME MEASURE

The occurrence of eclampsia in the two groups.

RESULTS

The data of 699 women were evaluated. Fourteen were withdrawn after randomisation. The overall incidence of eclampsia was 1.8%. Of 345 women who received magnesium sulphate, one developed eclampsia (0.3%); in the placebo group, 11/340 women (3.2%) developed eclampsia (relative risk 0.09; 95% confidence interval 0.01-0.69; P = 0.003).

CONCLUSION

The use of intravenous magnesium sulphate in the management of women with severe pre-eclampsia significantly reduced the development of eclampsia.

Magnesium sulphate in the treatment of eclampsia and pre-eclampsia: an overview of the evidence from randomised trials

OBJECTIVE

To evaluate the effectiveness of magnesium sulphate in the treatment of eclampsia and pre-eclampsia by a systematic quantitative overview of controlled clinical trials.

DESIGN

Online searching of the MEDLINE database between 1966 and 1995, and scanning of the bibliography of known primary studies and review articles on the use of magnesium sulphate in eclampsia and pre-eclampsia. Study-selection, study quality assessment and data extraction were performed independently by two reviewers under masked conditions. Where possible outcome data from trials were pooled and summarised using the Mantel-Haenszel method.

PARTICIPANTS

One thousand seven hundred and forty-three women with eclampsia and 2390 with pre-eclampsia included in nine randomised trials that evaluated the effects of magnesium sulphate.

MAIN OUTCOME MEASURES

Seizure activity and maternal death.

RESULTS

In eclampsia, recurrence of seizures was less common with magnesium sulphate therapy compared with phenytoin (odds ratio [OR] 0.27, 95% CI 0.17-0.45, P = 0.00) and diazepam (OR 0.41, 95% CI 0.30-0.57, P = 0.00). As indicated by the point estimate, there was a trend towards a reduction in maternal mortality with magnesium sulphate in eclampsia (OR 0.51, 95% CI 0.24-1.07, P = 0.10 versus phenytoin; OR 0.78, 95% CI 0.41-1.45, P = 0.52 versus diazepam). When used for seizure prophylaxis in pre-eclampsia, magnesium sulphate was found to be more effective than phenytoin (OR 0.15, 95% CI 0.03-0.72, P = 0.01).

CONCLUSION

Magnesium sulphate is a superior drug in preventing the recurrence of seizures in eclampsia and in seizure prophylaxis in pre-eclampsia.

Magnesium sulfate adversely affects fetal lamb survival and blocks fetal cerebral blood flow response during maternal hemorrhage

Magnesium sulfate is commonly used in high-risk pregnancies, even though its actions in the fetus during maternal/fetal stress are not completely understood. The present study tested the hypothesis that magnesium sulfate alters the fetal cerebral blood flow response to hypoxemia produced during maternal hemorrhage. It was conducted in instrumented near-term fetal lambs at 123 days of gestation. Experimental treatment involved four periods of maternal hemorrhage over a 60-min period during fetal infusion of 0.25 g (n = 5) or 0.30 g (n = 6) magnesium sulfate, or normal saline (n = 11). The level of fetal cerx500l blood flow was determined using radiolabeled microspheres. For all three treatment groups, maternal hemorrhage produced fetal hypoxemia and some fetal demise. During fetal infusion of saline, 1 of 11 (9%) of the fetuses died; with the 0.25-g magnesium sulfate regimen, 1 of 5 (20%) died; and with the 0.30-g magnesium sulfate regimen, 3 of 6 (50%) of the fetuses died. Magnesium sulfate caused an increase in the proportion of fetal death produced by maternal hemorrhage (P < 0.05). Among surviving fetuses, hemorrhage-induced hypoxemia increased fetal cerebral blood flow during saline infusion. In contrast, infusion of magnesium sulfate had an inhibitory effect on this compensatory increase in fetal cerebral blood flow (P = 0.003). These data indicate that, in the sheep, magnesium sulfate increases fetal mortality and inhibits the compensatory increase in fetal cerebral blood flow during maternal hemorrhage-induced fetal hypoxemia.

A comparison of magnesium sulfate with phenytoin for the prevention of eclampsia

BACKGROUND

Magnesium sulfate is used widely to prevent eclamptic seizures in pregnant women with hypertension, but few studies have compared the efficacy of magnesium sulfate with that of other drugs. Anticonvulsant prophylaxis with phenytoin for eclampsia has been recommended, but there are virtually no data to support its efficacy. Our objective was to compare magnesium sulfate with phenytoin in preventing seizures in hypertensive women during labor.

METHODS

We randomly assigned women with hypertension who were admitted for delivery to receive either magnesium sulfate or phenytoin. The magnesium sulfate regimen consisted of a 10-g intramuscular loading dose followed by a maintenance dose of 5 g given intramuscularly every four hours. For women with severe preeclampsia, an additional 4-g loading dose was given intravenously. The phenytoin regimen included a 1000-mg loading dose infused over a period of 1 hour, followed by a 500-mg oral dose 10 hours later. With either regimen, anticonvulsant therapy was continued for 24 hours post partum.

RESULTS

Ten of 1089 women randomly assigned to the phenytoin regimen had eclamptic convulsions, as compared with none of 1049 women randomly assigned to magnesium sulfate (P = 0.004). There were no significant differences in any risk factors for eclampsia between the two study groups. Maternal and infant outcomes were also similar in the two study groups.

CONCLUSIONS

Magnesium sulfate is superior to phenytoin for the prevention of eclampsia in hypertensive pregnant women. These results validate the long-practiced use of magnesium sulfate in the prevention of eclampsia.