Pregnancy prognosis according to prepregnancy body mass index and gestational weight gain in twin pregnancies

Methods The study subjects were 500 twin pregnant women and their 1,000 babies delivered from January 2008 to December 2010. The women divided in 4 groups according to prepregnancy BMI; underweight (BMI<18.5 kg/m), normal weight (18.5≤BMI<23 kg/m), overweight (23.0≤BMI<25 kg/m), and obese (BMI≥25 kg/m) and also categorized 3 groups according to gestational weight gain; “poor” if it was below the IOM range for the prepregnancy BMI, “normal” if it was within the range, and “excessive” if it was above the range.