Lifestyle intervention to improve outcomes in dichorionic twin pregnancies: study protocol for a multicentre randomised controlled trial with an integrated pilot study - the LIFETWIN trial

Introduction: Preterm birth and small-for-gestational-age (SGA) infants remain major contributors to neonatal morbidity, mortality and healthcare costs. Twin pregnancies account for a disproportionate share of these adverse outcomes, representing 18%–24% of all preterm births in Europe. Despite this high-risk profile, effective preventive strategies for twin pregnancies remain limited and mainly target cervical length. Emerging evidence suggests that maternal lifestyle factors, including diet, physical activity and stress management, may prolong gestational age and improve fetal growth.

Methods and analysis: The LIFEstyle intervention to improve TWIN pregnancy (LIFETWIN) - study is a multicentre, open-label, randomised controlled trial. A total of 274 women with dichorionic twin pregnancies will be recruited across 15 sites in Belgium. The full trial will be preceded by an integrated pilot study conducted at four sites to assess feasibility using the RE-AIM framework. Participants will be randomised to standard care or a lifestyle intervention in addition to standard care. The intervention consists of eight midwife-led sessions between gestational weeks 16 and 36, focusing on a Mediterranean-type diet, physical activity, mindfulness and prenatal multivitamin supplementation. Data are collected at baseline, in late pregnancy, at delivery and at 6 weeks postpartum, using clinical records, physical examinations and validated questionnaires. The primary outcome is gestational age at delivery. Secondary outcomes include neonatal birth weight, SGA status, neonatal morbidity and mortality, neonatal intensive care unit admission and length of stay, maternal gestational weight gain, postpartum weight and quality of life. The primary outcome, gestational age at delivery, will be analysed using a linear mixed-effects model, accounting for study-site effects and potential clustering by intervention midwife within the intervention arm. Secondary outcomes will be analysed using models appropriate to the outcome type, including linear mixed models, generalised mixed models and frailty models.