Adaptive Mobile Health Intervention to Reduce Excess Gestational Weight Gain: A Cluster-Randomized Clinical Trial

Excessive gestational weight gain (GWG) occurs in 50% of pregnant patients with overweight or obesity and is associated with several perinatal complications. Scalable, evidence-based lifestyle interventions are needed.

To test whether an adaptive mobile health lifestyle intervention plus standard care reduces excessive GWG compared with standard care alone.

This cluster-randomized clinical trial, with randomization at the clinician level, enrolled pregnant patients with a singleton pregnancy, prepregnancy body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) 25.0 to less than 40.0, and receiving care within an integrated health system. Data were analyzed from May 1, 2024, to February 12, 2026.

Clinicians randomized to the intervention received motivational interviewing guidance for discussing GWG, and their patients received personalized, automated feedback on GWG and physical activity via a smartphone application; a wireless scale and activity tracker; 13 weekly education topics delivered via app; and step-wise chats and/or phone support from a lifestyle coach, for those experiencing accelerated GWG.

The co-primary outcomes were weekly rate of GWG and total GWG (both continuous and categorized per IOM guidelines).

From a total of 58 clinicians who consented to participate, 1265 patients (mean [SD] age, 33.4 (4.6) years; mean [SD] prepregnancy BMI, 29.8 [3.8]) consented to participate and were enrolled in the trial, including 677 patients in the intervention group and 588 patients in the standard care condition. The weekly rate of GWG was significantly lower in the intervention group vs standard care group (mean [SD] rate, 0.25 [0.20] vs 0.28 [0.20] kg/week; mean between-group difference, -0.03 [95% CI, -0.05 to -0.01] kg/week). Fewer patients in the intervention group exceeded IOM guidelines for weekly rate of GWG than in the standard care group (351 patients [51.9%] vs 354 patients [60.2%]; RR, 0.86 [95% CI, 0.78-0.95]), while more patients gained below the guidelines (148 patients [21.8%] vs 101 patients [17.2%]; relative risk [RR], 1.27 [95% CI, 1.01-1.61]). Total GWG was significantly lower in the intervention group than the standard care group (mean [SD], 9.7 [6.2] vs 10.6 [6.2] kg; mean between-group difference, -0.87 [95% CI, -1.40 to -0.34] kg). Fewer patients in the intervention exceeded IOM guidelines for total GWG than in standard care (299 patients [44.1%] vs 301 patients [51.2%]; RR, 0.87 [95% CI, 0.77-0.98]) while more patients gained below the total GWG guidelines [182 patients [26.8%] vs 126 patients [21.5%]; RR, 1.23 [95% CI, 1.04-1.45]).

This cluster-randomized trial found that an adaptive intervention leveraging technology effectively reduced the rate of GWG and total GWG among pregnant patients with overweight or obesity.

ClinicalTrials.gov Identifier: NCT03880461.