Restricted gestational weight gain (GWG) following lifestyle interventions for gestational diabetes mellitus (GDM) has been observed in clinical trials but not been explicitly confirmed in real-world clinical settings. Furthermore, how such a restricted GWG affects adverse birthweight outcomes, i.e. infants born large/small for gestational age (LGA/SGA), remains unclear. In this retrospective study, based on longitudinal weight measurements from 33,515 Chinese women, including 5,932 with GDM diagnosed by 75-g oral glucose tolerance test (OGTT), we compared the adjusted GWG trajectories of women with and without GDM. We estimated weekly GWG before and after OGTT (WGWG pre−OGTT and WGWG post−OGTT ) and calculated ΔWGWG as WGWG pre−OGTT minus WGWG post−OGTT . We then estimated the adjusted relative risks (aRR) of LGA and SGA for restricted vs. unrestricted WGWG post−OGTT (ΔWGWG > 0 vs. ≤0 kg) among women with GDM. The analyses were stratified by prepregnancy body mass index (pBMI). There was a marked decrease between the mean estimated WGWG pre−OGTT (0.50 kg) and WGWG post−OGTT (0.36 kg) in women with GDM, in contrast to a negligible decrease from 0.52 to 0.51 kg in women without GDM. Using 14–19 gestational weeks as the baseline, the cumulative GWG since the baseline became statistically significantly less in women with than without GDM after the initiation of lifestyle interventions, regardless of their pBMI category. Women with an underweight, normal-weight, and overweight/obese pBMI gained by an adjusted median of 1.84 95% confidence interval (CI): 1.50, 2.17, 2.53 (2.38, 2.68), and 2.99 kg (2.63, 3.35) less, respectively, than their non-GDM counterparts by the end of gestation (38–39 weeks). Among women with GDM, a restricted WGWG post−OGTT showed no association with either LGA or SGA for underweight pBMI, a null association with SGA but a statistically significant association with a reduced risk of LGA for normal-weight pBMI aRR (95% CI): 1.02 (0.82, 1.28) and 0.62 (0.49, 0.79), respectively, and opposite although non-significant associations for overweight/obese pBMI aRR (95% CI): 1.22 (0.66, 2.28) for SGA and 0.74 (0.52, 1.06) for LGA. Lifestyle interventions for GDM are likely to cause a substantially restricted GWG, which however might only have a fully beneficial effect on infant birthweight for women with a normal-weight pBMI.
Li et al. (Thu,) studied this question.