Interaction and joint association of gestational diabetes mellitus and subsequent weight gain rate on macrosomia

Abstract

Background & aims: Gestational diabetes mellitus (GDM) and gestational weight gain are two crucial modifiable nutritional factors during pregnancy in preventing macrosomia, warranting appropriate management of both glycemic levels and weight gain to prevent macrosomia, particularly in individuals with GDM. Unfortunately, current general weight targets appear not to apply to individuals with GDM, suggesting that weight gain, specifically following an oral glucose tolerance test (OGTT), may affect risk of macrosomia dependent on GDM status. Therefore, this study aims to evaluate the interaction and joint association of GDM and post-OGTT weight gain rate (PWGR) in relation to macrosomia.

Methods: This was a population-based cohort study of 59,421singleton pregnant women in South China during 2017-2020. Among them, 9856 were diagnosed with GDM while 49,565 did not have the condition. All participants underwent an OGTT between 20 and 28 weeks of pregnancy, typically occurring between 24 and 28 weeks. PWGR was defined as the average rate of change in maternal weight with gestational weeks following OGTT, which was estimated using a repeated linear mixed effects model including a random intercept and slope for each individual. The relative risk (RR) of macrosomia associated with GDM and PWGR was estimated using a multivariate generalized linear model.

Results: There was a significant interaction between GDM and PWGR in increasing the risk of macrosomia. The combination of GDM and a 1-SD increase in PWGR was associated with a 2.26-fold higher risk of macrosomia (95% CI 1.92 to 2.65), with the interaction of these two factors contributing to 58.0% (95% CI 31.4%-84.7%) of this association. Moreover, we observed a significant heterogeneity in susceptibility to macrosomia due to increased PWGR between GDM and non-GDM populations, with the highest PWGR quartile having respective RRs of 2.27 (95% CI 1.62 to 3.18) and 1.41 (95% CI 1.18 to 1.69) compared to the lowest quartile category, which was corresponded to 55.9% (95% CI 38.3%-68.6%) and 29.1% (95% CI 15.3%-40.8%) preventable proportions of macrosomia cases in these populations.

Conclusions: GDM and PWGR had a synergistic effect in increasing the risk of macrosomia. Furthermore, individuals with GDM exhibited a heightened susceptibility to macrosomia due to elevated PWGR. These findings emphasize the importance of appropriate weight interventions during late pregnancy and suggest the need for different weight targets between these two populations, with a stricter PWGR potentially being more effective for the GDM population.

Keywords: Gestational diabetes mellitus; Interaction; Macrosomia; Oral glucose tolerance test; Weight gain rate; Weight management.