Does Excess First- or Second-Trimester Weight Gain Predict Excess Total Gestational Weight Gain? A Multicentre Prospective Cohort Study.

Objectives: Early excess gestational weight gain (GWG) has been examined as a predictor of total excess GWG in a few international studies; however, Canadian data are lacking. We sought to determine whether early (first- and second-trimester) excess GWG predicted total excess GWG.

Methods: We conducted an a priori planned secondary analysis of a multicentre prospective study of English-speaking Ontario women with a singleton pregnancy between 8 and 20 weeks gestation. Our primary outcome was prediction of total excess GWG. We calculated the sensitivity, specificity, predictive values, and likelihood ratios, by body mass index (BMI), for excess first- and second-trimester GWG.

Results: Of the 970 women who met the inclusion criteria, 387 and 754, had first- and second-trimester weights recorded in their antenatal record, respectively. For normal, overweight, and obese women, the sensitivity of excess first-trimester GWG for total excess gain was 66%, 68%, and 65%, respectively; and the specificity was 48%, 43%, and 36%, respectively. The sensitivity of excess second-trimester GWG for total excess gain for normal weight, overweight, and obese women was higher, at 92%, 96%, and 95%, respectively; while the specificity was low at 31%, 16%, and 29%, respectively.

Conclusion: In the first known Canadian study of early excess weight gain as the predictor of total GWG, we found that excess first-trimester GWG did not predict total excess GWG, but that the sensitivity of excess second-trimester GWG for excess total GWG was high across BMI categories.