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 greater than or equal to 140/90 mmHg and greater than or equal to 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.