“…The five (24,28,35,39,52) remaining studies obtained weight and height measures from medical records. In order to categorize pre-pregnancy BMI into weight classes, 19 (15,22,23,25,27,30,33,34,38,(40)(41)(42)46,(48)(49)(50)52,54,56) studies used the World Health Organization's BMI cut-offs, and another 16 (2,7,8,18,21,26,28,29,32,35,36,43,45,47,51,53) studies used guidelines consistent with these. A further six (24,31,37,39,44,55) studies used the 1990 Institute of Medicine (IOM) (57) BMI cut-offs to determine prepregnancy BMI classifications.…”