A Supervised Hybrid Prenatal Exercise Program Reduces the Incidence of Macrosomia: A Randomized Controlled Trial

PURPOSE: To examine the effects of a supervised hybrid prenatal exercise program (combined in-person and online sessions) on the incidence of macrosomia and excessive gestational weight gain (EGWG). METHODS: A randomized clinical trial (NCT04563065) was conducted. A total of 260 pregnant women were assessed for eligibility and randomized (1:1). This manuscript reports results from a per-protocol analysis including 138 participants (exercise group [EG] n=62; control group [CG] n=76). The EG participated in a supervised moderate-intensity exercise program delivered in a hybrid format (1 in-person session/week at the hospital and 2 online sessions/week via Zoom), from 11 weeks' gestation until delivery. The CG received usual obstetric care, printed lifestyle education materials, and a brief phone-based physical activity interview once per trimester. Macrosomia (>4000 g) and EGWG (Institute of Medicine criteria) were extracted from hospital records and compared between groups. RESULTS: The incidence of macrosomia was lower in the EG (0%) than in the CG (7.3%; χ²=6.70, p=0.01). The incidence of EGWG did not differ between groups (9.6% vs. 19.4%, p=0.13). Apgar score at 5 minutes was slightly higher in the EG than in the CG (9.91±0.34 vs. 9.82±0.56, p=0.03). CONCLUSIONS: A supervised hybrid prenatal exercise program was associated with a lower incidence of macrosomia and slightly higher 5-minute Apgar scores compared with usual care. These findings support hybrid delivery as a feasible strategy for implementing supervised prenatal exercise.