LONDON — Giving injections of magnesium sulfate to expectant mothers who have preeclampsia can halve their risk of seizures and save their lives, a major new study has found.
The results were so impressive that the ethics board overseeing the research stopped the study early because it would have been unethical to deprive the women not getting the treatment.
Preeclampsia, characterized by a sudden increase in blood pressure in late pregnancy, is one of the most dangerous and baffling complications of pregnancy.
A common treatment until now has been to induce delivery of the baby in hopes it can be born before the mother develops seizures, called eclampsia.
Doctors in the United States have been using magnesium sulfate, commonly known as Epsom salts, to treat preeclampsia for decades but without reliable evidence that it works or that it does more good than harm. It has rarely been used for preeclampsia in other countries.
Blood vessels are supposed to widen in early pregnancy as blood flow increases. Scientists believe that a preeclamptic woman’s vessels are constricted from the beginning, reducing blood flow to the fetus and her own organs. Scientists suspect that magnesium sulfate might work by relaxing the walls of the blood vessels to the brain.
Experts called the findings, published this week in the Lancet medical journal, definitive.
Worldwide, preeclampsia and eclampsia occur in about 10 per cent of pregnant women and account for about 12 percent of pregnancy-related deaths, according to the World Health Organization.
The condition is much more common in developing countries.
About a third of the tune, preeclampsia develops before natural labor. In mild cases, the problem is controlled by putting the mother on bed rest and a low-salt diet
The research is also the first to provide reliable safety evidence. Scientists were worried that, because magnesium sulfate decreases contractions in the womb, the women would be more likely to need a cesarean section, but they weren't.
The international study, coordinated by scientists at the Institute of Health Sciences in England involved 10,141 women in 33 countries.
Half received the treatment and half were given a placebo.
The researchers had planned to recruit 14,000 women but by the time they got to 10,141, the committee overseeing the experiment had analyzed the results from the first 8,483 pregnancies.
Magnesium sulfate was so good the committee decided to stop the study immediately.
The final analysis showed that women who received magnesium sulfate had a 55 percent lower risk of eclampsia — 40 of them had a seizure, compared with 96 getting the fake drug.
Women getting magnesium sulfate also had a 45 percent lower risk of dying — 11 died, compared with 20 in the comparison group.
The treatment didn’t improve the babies’ chances of surviving, but it didn’t harm them.
Blood vessels are supposed to widen in early pregnancy as blood flow increases. Scientists believe a pre-eclamptic woman’s vessels are constricted from the beginning, reducing blood flow to the fetus and her own organs, thus potentially causing kidney and other damage.
This page was first uploaded to The Magnesium Web Site on June 3, 2002