The scarce details given of the review processes prevent proper assessment of the quality of this article consequently any conclusions should be treated with caution. Generally, the studies are summarised in the narrative however, statistical pooling has been used for one group of studies (patients with severe pre- eclampsia), without explanation.

Only very limited study details are given in the tables and not all the studies are discussed in the text. No details are given of the processes involved in study selection, validity assessment or data- extraction. The authors maintain that the included studies were assessed in terms of 'levels of evidence' but these are not presented for the included studies. The inclusion criteria were briefly described in the abstract but the rationale for the inclusion of non-randomised material is unclear.

It is possible that relevant literature, especially any published in languages other than English, may have been missed. Magnesium sulfate or magnesium sulphate (in English-speaking countries other than the US) is a chemical compound, a salt with the formula MgSO 4, consisting of magnesium cations Mg 2+ (20.19 by mass) and sulfate anions SO 2 4.It is a white crystalline solid, soluble in water but not in ethanol. Only one database was searched for relevant literature and this was limited to English language however, additional references were sought in bibliographies and through consultation with experts. This review is based on a fairly well defined question, which details the target population and intervention.