Adaptive Mobile Health Lowers Gestational Weight Gain in Cluster Trial

Key Takeaways

• The intervention group had lower weekly and total gestational weight gain than the standard care group.
• Fewer intervention patients exceeded Institute of Medicine thresholds for weekly and total gestational weight gain, with relative risks below 1 for both outcomes.
• The trial used clinician-level cluster randomization in an integrated health system and evaluated a multicomponent program with motivational interviewing support, app feedback, and connected devices.

An adaptive mobile health lifestyle intervention was associated with 0.87 kg less total gestational weight gain than standard care in a cluster-randomized clinical trial of pregnant patients with singleton pregnancies and prepregnancy BMI 25.0 to less than 40.0. Care was delivered within an integrated health system among pregnant patients with overweight or obesity. The intervention was also associated with fewer patients exceeding Institute of Medicine guideline thresholds.

Randomization occurred at the clinician level, with 58 clinicians participating across the integrated health system. The trial enrolled 1,265 patients, with 677 assigned to the intervention group and 588 to standard care. Mean age was 33.4 years, mean prepregnancy BMI was 29.8, and data were analyzed from May 1, 2024, to February 12, 2026. The program paired clinician motivational interviewing guidance with app feedback, a wireless scale and activity tracker, 13 weekly education topics, and stepwise coach chats or calls for accelerated weight gain. Co-primary outcomes were weekly rate and total gestational weight gain, assessed continuously and by Institute of Medicine categories.

Weekly gestational weight gain averaged 0.25 (0.20) kg/week with the intervention and 0.28 (0.20) kg/week with standard care. The mean between-group difference was -0.03 kg/week, with a 95% CI from -0.05 to -0.01. Total gestational weight gain was 9.7 (6.2) kg versus 10.6 (6.2) kg, yielding a mean difference of -0.87 kg with a 95% CI of -1.40 to -0.34. Both co-primary continuous outcomes favored the intervention.

For weekly guidelines, 51.9% of intervention patients and 60.2% of standard care patients exceeded Institute of Medicine thresholds, giving an RR of 0.86 (95% CI, 0.78-0.95). For total gain, 44.1% versus 51.2% exceeded guidelines, with an RR of 0.87 (95% CI, 0.77-0.98). Below-guideline weekly gain occurred in 21.8% versus 17.2%, with an RR of 1.27 (95% CI, 1.01-1.61). Below-guideline total gain occurred in 26.8% versus 21.5%, with an RR of 1.23 (95% CI, 1.04-1.45). Investigators interpreted these findings as reductions in gestational weight gain rate and total amount with the technology-enabled adaptive intervention.