Further development and (cost-)effectiveness of the Smarter Pregnancy lifestyle program tailored for pregnant women with obesity (HYGEIA trial)

Maternal obesity affects approximately 16% of pregnancies worldwide and is a major concern for public health. This condition is associated with elevated risks of adverse outcomes, such as gestational diabetes, hypertensive disorders of pregnancy, and cardiovascular and metabolic disease (CVMD) during the life course. Our long-term experience with the (cost-)effective web-based Smarter Pregnancy coaching program is promising to mitigate these risks and improve lifestyle behaviours as well as maternal and neonatal health outcomes. Here our aim is to describe the rationale and study protocol for a randomised controlled trial (RCT) to investigate the clinical and cost-effectiveness, and implementation potential of Smarter Pregnancy Plus (SP+) from early pregnancy onwards in women with obesity. The HYGEIA study is designed as a multicentre, two-armed RCT. A total of 930 women with a body mass index ≥30 kg/m² and a singleton pregnancy of ≤14 weeks gestation will be recruited and randomised 1:1 to the intervention (n=465) and control group (n=465). The intervention group will receive six months of digital lifestyle coaching via the SP+ application, supported by at least one video consultation. SP+ is an extended, co-designed and tailored app version for pregnant women with obesity based on the validated SP program. It provides evidence-based coaching on nutrition, physical activity, mental health, folic acid and vitamin D supplement use, and smoking and alcohol cessation. The control group will receive usual care. Data will be collected through validated questionnaires, electronic medical records, financial records, and qualitative stakeholder sessions, guided by the Non adoption, Abandonment, Scale-up, Spread and Sustainability (NASSS)-framework. The primary outcome is the incidence of maternal CVMD during pregnancy, assessed using a composite measure that includes gestational diabetes, hypertensive disorders of pregnancy, and worsening of pre-existing hypertension or diabetes. Secondary outcomes include changes in lifestyle behaviours, maternal and neonatal outcomes, quality of life, and cost-effectiveness. Tertiary outcomes involve patient satisfaction, provider feasibility and a roadmap for nationwide implementation. The HYGEIA study will provide evidence on the clinical impact, cost-effectiveness, and implementation potential of SP+ as a digital lifestyle intervention for pregnant women with obesity. If successful, SP+ could further enhance routine obstetric care and contribute to improving maternal and neonatal health while reducing healthcare costs. Dutch Trial Registration number NL-OMON57196 (URL: https://onderzoekmetmensen.nl/nl/node/57196/pdf), date of registration 19-12-2024.