The Pharmaceutical Journal
Vol 268 No 7201 p793-795
8 June 2002

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Care of pre-eclampsia set to change

A change in the management of pre-eclampsia is expected following publication of trial results showing that magnesium sulphate halves the risk of eclampsia for pregnant women with pre-eclampsia (The Lancet 2002;359:1877).

Dr Lelia Duley, obstetric epidemiologist, Institute of Health Sciences, University of Oxford, and colleagues from the Magpie Trial Collaborative Group, conducted the three-year study after a systematic review in 1998 concluded that magnesium sulphate was the most promising treatment choice for pre-eclampsia.

They randomised 10,141 women with pre-eclampsia in 33 countries to receive magnesium sulphate or placebo. Treatment was given either intravenously or intramuscularly depending on local practice.

The trial was stopped early when data showed a clear benefit for women allocated to magnesium sulphate. At a briefing to present the trial results, Professor Jim Neilson, consultant obstetrician, Liverpool Women's Hospital, said: "It is very clear cut. The trial results clearly indicate that women with pre-eclampsia should have access to magnesium sulphate. We should see a rapid change in practice."

The researchers found that there were fewer eclamptic convulsions among women given magnesium sulphate (0.8 per cent compared with 1.9 per cent), equivalent to 11 fewer women with eclampsia per 1,000 women. The effect was consistent regardless of severity of pre-eclampsia, stage of pregnancy at trial entry, whether an anticonvulsant had been given previously, or whether treatment was given before or after delivery. The trend in maternal mortality favoured magnesium sulphate with 11 deaths (0.2 per cent) among women given magnesium sulphate compared with 20 (0.4 per cent) among those given placebo. However, the researchers say that a small increase in mortality has not been excluded.

Professor Neilson said that it had not been known whether the benefits of magnesium sulphate would outweigh its disadvantages. "There were concerns that the use of magnesium sulphate would increase the risk of women having to have a caesarian section [because magnesium sulphate decreases contractions in the uterus]. But it did not."

The researchers say that one reason why magnesium sulphate has not been used more widely for the management of pre-eclampsia is concern about the risk of respiratory depression. In this study, more women given magnesium sulphate had respiratory depression than those given placebo. However, the researchers say that the actual numbers were small and that there was no overall difference in serious maternal morbidity. A quarter of women given magnesium sulphate reported side effects compared with 5 per cent of women given placebo.

Professor Neilson noted that there is no evidence to suggest that magnesium sulphate prevents complications in women who are at high risk of pre-eclamsia but who have not yet developed the condition. He stressed that treatment requires careful supervision and that women should not contemplate self-treatment.