Primary outcome
The intervention was completed as planned. Adherence to the intervention was as follows: 55 (42%) participants attended ≥75% of the exercise sessions, 47 (35%) attended 50–74% of the sessions, and 31 (23%) attended fewer than half of the exercise sessions.
We found no effect of supervised group exercise on psychological well-being measured by the WHO-5 at gestational week 29–34. The mean WHO-5 score was 60.5 (95% CI: 58.1–63.0) in the intervention group and 58.5 (95% CI: 56.0–61.1) in the control group, mean difference between the two groups being 2.0 (95% CI: -1.3 to 5.2, p=0.23) (Table 2).
The prespecified perprotocol analysis of women attending ≥75% of the exercise sessions showed a statistically significant higher WHO-5 mean score in the intervention subgroup compared to the control group at gestational week 29–34, mean difference 5.5 (95% CI: 0.8-10.2, p=0.02).