Qi Y, Sun X, Tan J, et al. - Among women pregnant with singletons, researchers conducted this cohort study to assess gestational weight gain (GWG) in the first and second trimester as a risk factor for gestational diabetes mellitus (GDM). The sample consisted of women with singleton pregnancies who delivered between January 1, 2013 and October 31, 2014 in a Chinese hospital. During the second trimester, all pregnant women were subjected to an oral glucose tolerance test (OGTT) for GDM diagnosis. GWG was calculated by subtracting pre‐pregnancy weight from weight within 4 weeks of OGTT during the first and second trimester. Of 10,422 pregnant women, 8,356 eligible women with 1,622 diagnosed with GDM were identified. Findings suggested that excessive GWG during the first and second trimester could be a risk factor for GDM, emphasizing the importance of sufficient weight gain during pregnancy.