Calculation of optimal gestation weight gain in pre-pregnancy underweight women due to body mass index change in relation to mother’s height

Background Optimal gestational weight gain has not yet been clearly defined and remains one of the most controversial issues in modern perinatology. The role of optimal weight gain during pregnancy is critical, as it has a strong effect on perinatal outcomes. Purpose In this study, gestational body mass index (BMI) change, accounting for maternal height, was investigated as a new criterion for gestational weight gain determination, in the context of fetal growth assessment. We had focused on underweight women only, and aimed to assess whether the Institute of Medicine (IOM) guidelines could be considered acceptable or additional corrections are required in this subgroup of women. Methods The study included 1205 pre-pregnancy underweight mothers and their neonates. Only mothers with singleton term pregnancies (37th–42nd week of gestation) with pre-gestational BMI