Joint and Independent Associations of Gestational Diabetes and Depression With Childhood Obesity.

Importance: Childhood obesity has been independently associated with exposure to gestational diabetes and prenatal depression. Although these conditions frequently co-occur and may share biological pathways, their combined association with childhood obesity remains unknown. Objective: To examine whether exposure to prenatal depression and gestational diabetes is separately and jointly associated with childhood obesity. Design, Setting, and Participants: This prospective cohort study of births from 2011 to 2021 used data from Kaiser Permanente Northern California, an integrated health care system. Individuals receiving prenatal care were universally screened for depression and gestational diabetes and their children's height and weight were monitored until age 10 years. Data analysis was performed from June 2024 to December 2025. Exposures: Gestational diabetes diagnosis and prenatal depression diagnosis and severity obtained from medical records. Main Outcomes and Measures: The primary outcome was childhood obesity, defined as Centers for Disease Control and Prevention body mass index z scores greater than or equal to the 95th percentile stratified by child age in years. Modified Poisson regression with robust SEs estimated risk ratios (RRs) for prenatal depression and gestational diabetes separately and jointly, adjusting for the birthing parent's age, race and ethnicity, neighborhood deprivation, parity, and prenatal alcohol and tobacco use. Effect modification was assessed separately by statistical interactions and stratified models. Results: In this cohort study of 203 333 birthing parent-child pairs (mean [SD] age of birthing parents at the time of delivery, 30.8 [5.3] years; 104 214 male children [51.3%]), rates of childhood obesity increased with child's age, from 14.6% (29 198 of 199 329 children) at age 2.0 to 4.9 years, to 16.5% (19 155 of 116 398 children) at age 5.0 to 7.9 years, and 21.8% (9798 of 44 894 children) at age 8.0 to 10.0 years. Prenatal depression was minimally associated with obesity (RR, 1.07 [95% CI, 1.04-1.10] for children aged 2.0-4.9 years; RR, 1.08 [95% CI, 1.04-1.12] for children aged 5.0-7.9 years; RR, 1.05 [95% CI, 1.00-1.11] for children aged 8.0-10.0 years). Gestational diabetes demonstrated larger effect estimates (RR, 1.29 [95% CI, 1.25-1.34] for children aged 2.0-4.9 years; RR, 1.45 [95% CI, 1.40-1.51] for children aged 5.0-7.9 years; RR, 1.39 [95% CI, 1.31-1.46] for children aged 8.0-10.0 years). Joint exposure to gestational diabetes and depression conferred the highest RRs compared with having neither exposure (RR, 1.33 [95% CI, 1.23-1.44] for children aged 2.0-4.9 years; RR, 1.54 [95% CI, 1.41-1.69] for children aged 5.0-7.9 years; RR, 1.43 [95% CI, 1.25-1.64] for children aged 8.0-10.0 years), with no evidence of interaction (P for interaction >0.10). After additionally adjusting for prepregnancy body mass index, joint results were attenuated, although the association for the 5.0 to 7.9 years age group remained especially robust. Conclusions and Relevance: In this cohort study, both prenatal depression and gestational diabetes were associated with childhood obesity risk, with larger effect sizes observed for gestational diabetes. Children exposed to both conditions had the greatest risk, although associations appeared additive rather than synergistic. These findings underscore the need for universal prenatal screening and risk stratification, along with targeted interventions for children exposed to these conditions.