A review of methodological quality of systematic reviews on multiple pregnancies

We set out to determine the quality of existing systematic reviews on multiple pregnancies. We conducted an electronic search in MEDLINE (1951 - 2005), EMBASE (1974 - 2005) and the Cochrane Database for Systematic reviews (2005:2) and a hand-search of reference lists without any language restrictions to identify relevant reviews. Two reviewers independently selected review articles in which a publicly available database was searched for studies concerning multiple pregnancies, and assessed them for quality of methods of review. Information was extracted on framing of question, literature search and data synthesis. Of 342 citations 14 (4%) eligible reviews were identified. Only 8/14 reviews specified the review question. Adequate literature search without language restriction and the use of a reference list was found in 7/14 reviews, but the risk of missing studies was assessed in only 1/14 reviews. Quality assessment of included studies was reported in 7/14 and tabulation of their findings was reported in 8/14 reviews, but heterogeneity of results was evaluated in only 4/14 reviews. Meta-analysis was employed in 3/14 reviews. Systematic reviews of existing studies on multiple pregnancies are infrequent and it is difficult to generate robust inferences from them as they lack good methodology.