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

Abstract

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. 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. 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<18.5kg/m2 were enrolled. The share of small for gestational age (SGA) infants in the study population was 16.2%. Our results showed the minimal recommended gestational weight gain of 12-14kg and BMI change of 4-5kg/m2 to be associated with a lower prevalence of SGA newborns. Based on our results, the recommended upper limit of gestational mass change could definitely be substantially higher. Optimal weight gain in underweight women could be estimated in the very beginning of pregnancy as recommended BMI change, but recalculated in kilograms according to body height, which modulates the numerical calculation of BMI. Our proposal presents a further step forward towards individualized approach for each pregnant woman.