Do trimester-specific cutoffs predict whether women ultimately stay within the Institute of Medicine/National Research Council guidelines for gestational weight gain? Findings of a retrospective cohort study

Background: It is unknown how well the trimester-specific recommendations for gestational weight gain (GWG) given by the Institute of Medicine/National Research Council (IOM/NRC) identify women at risk of GWG outside IOM/NRC recommendations for total GWG. Objective: We assessed the prognostic value of trimester-specific cutoffs for inadequate or excessive total GWG in term pregnancies. Design: Data on prepregnancy weight and the temporal course of GWG were collected from medical records. A total of 7962 women were included in the final analysis. Main outcome measures were inadequate or excessive total GWG as defined by criteria of the IOM/NRC. Main exposures were GWG outside the IOM/NRC week-specific recommendations in the first, second, and third trimesters. Results: The prediction of gaining weight within the GWG recommendations increased with gestational age and was related to the maternal weight category and outcome. In the second trimester, inadequate GWG was predicted with a sensitivity of 49% and 60.2% and a positive predictive value (PPV) of 72.1% and 68.3% in underweight and normal-weight mothers, respectively. Excessive GWG was predicted with a sensitivity of 72.7% and 70.4% and a PPV of 94.3% and 93.3% in overweight and obese mothers, respectively. Conclusions: On the basis of second-trimester specific guidelines, inadequate GWG can be predicted in underweight and normal-weight mothers, whereas excessive GWG can be predicted in overweight and obese mothers. Therefore, it appears possible to identify women at risk of gaining outside of the guideline as early as the second trimester. Am J Clin Nutr 2012;95:1432-7.