Antenatal lifestyle interventions to reduce gestational weight gain: Where should we start and how much will it cost?

Objectives Antenatal lifestyle interventions are effective in reducing negative outcomes associated with excess gestational weight gain. While strong cost-effectiveness has also been demonstrated, the cost of implementation is potentially a barrier to uptake. We aimed to estimate whether targeted implementation in high risk clinical groups (categorized by age, body mass index (BMI) and gravidity) returns greater health cost savings through a reduction in aggregate incidence of adverse pregnancy and birth outcomes. Study design Distributional budget impact analysis utilising population level linked data collections. Methods Total budget expenditure (cost of intervention minus cost savings from the associated reduction in adverse pregnancy outcomes) of implementing the lifestyle intervention in risk targeted population sub-groups was estimated, stratified by health system (public vs. private funding). Results Total annual budget expenditure if the intervention is routinely provided to 80 % of pregnant women in New South Wales and Queensland, Australia, is projected to be AU$11,654,857 for n = 94,539 public patients, and AU$6,527,434 for n = 33,516 private patients. If implemented in the BMI ≥30 kg/m 2 group only, expenditure is reduced to AU$643,339 for n = 10,298 public patients, and AU$579,003 for n = 5018 private patients, while for implementation in the Age ≥35 years group, it was AU$1,290,965 (n = 21,071 public) and AU$2,169,851 (n = 12,776 private). The number of adverse pregnancy outcomes averted per women was greatest in the BMI ≥30 kg/m 2 group. Conclusions Women in the highest BMI category should be prioritised for implementation of effective and cost-effective antenatal lifestyle intervention to reduce the aggregate budgetary impact of adverse pregnancy outcomes.