Interpregnancy and pregnancy lifestyle intervention (INTER-ACT): a randomized controlled trial

Lifestyle interventions prior to conception hold potential to reduce pregnancy-related complications, although this has been constrained due to challenges in reaching preconception women.

We aim to study the effectiveness of the interpregnancy and pregnancy lifestyle intervention (INTER-ACT) lifestyle intervention spanning through the interpregnancy and subsequent pregnancy periods in women with a history of excessive gestational weight gain on reducing pregnancy complications.

The Interpregnancy Coaching for a Healthy Future (INTER-ACT) study is a prospective, multicenter randomized controlled trial.

Participants were recruited within 6 weeks after a previous pregnancy from a combination of primary and secondary healthcare facilities across 6 Flemish hospitals in Belgium. The INTER-ACT intervention involved face-to-face coaching sessions and an E-Health application aimed at promoting healthy behaviors, including nutrition, physical activity, and mental wellbeing. The primary outcome was a composite of pregnancy complications including pregnancy-induced hypertension, gestational diabetes, cesarean section, and large for gestational age infants. To identify a significant difference between the intervention and control group in the incidence of composite outcome, with a statistical power of 80% and significance level of 0.05, 250 women with subsequent delivery in each group needed to be recruited.

Participants were recruited from May 2017 through April 2019. Of 8897 women with excessive gestational weight gain, 1450 were randomized. Three hundred and ninety subsequently experienced singleton pregnancy, with 193 in the intervention group and 197 in usual care. Baseline sociodemographics were generally comparable between groups. The lifestyle intervention did not significantly reduce the composite outcome (odds ratio, 1.29; 95% confidence interval, 0.85-1.96; P=.23) or secondary outcomes. In a post hoc subanalysis, we found that adherence to follow-up during the subsequent pregnancy was associated with a reduced risk of the composite outcome in both study arms (intervention group: odds ratio, 0.50, 95% confidence interval, 0.26-0.98, P=.04; control group: odds ratio, 0.48, 95% confidence interval, 0.26-0.90, P=.02), suggesting a potential benefit of continued engagement regardless of allocation.

The INTER-ACT intervention did not result in a lower composite outcome rate in women with previous excessive gestational weight gain. However, adherence during pregnancy was key, halving risks in both study arms. Future trials should focus on improving adherence and exploring the impact of lifestyle interventions on pregnancy outcomes in women across diverse body mass index ranges, particularly in the preconception and interpregnancy periods.