Cost effectiveness of a controlled lifestyle intervention for pregnant women with obesity.

Background: The Mighty Mums antenatal lifestyle intervention is a person-centered behavioral intervention focusing on nutrition and physical activity for pregnant women with obesity (body mass index [BMI] ≥30). The aim of this study was to evaluate the costs and clinical outcomes of adding the Mighty Mums intervention to standard antenatal care.

Methods: Participants in the intervention group (n = 434) received motivational talks with their midwife and a selection of physical and/or nutritional activities in addition to antenatal care. Control participants (n = 867) from adjacent geographic areas received standard antenatal care. Costs for staff, unit costs for specific activities, and registered costs for specialized antenatal care were analyzed for associations with gestational weight gain and self-reported health. Results are reported for the intention-to-treat (ITT) population and a per protocol (PP) population identified by participation in the intervention. Analyses included bootstrapped linear regressions adjusted for background characteristics that differed significantly between groups.

Results: The average costs were SEK 9727 higher (95% confidence interval [CI]: 6677 to 12,777) among participants in the intervention group than in the control ITT population and SEK 8655 (95% CI 4586 to 12,724) higher than in the PP population. The cost increase per 1 kg reduction in gestational weight gain was SEK 12,369 in the ITT population and SEK 7209 for the PP population.

Conclusion: Participation in the Mighty Mums intervention was associated with higher costs, but also reduced gestational weight gain. The cost per kilogram reduction in gestational weight gain was low, particularly in the PP population. A future decision to implement this behavioral intervention in standard care should take into account society's willingness to pay per unit reduction in gestational weight gain.

Trial Registration: The study is registered at ClinicalTrials.gov , Identifier: NCT03147079 .