SUpporting Mothers Milk Intervention Trial (SUMMIT) — a randomised controlled trial comparing different doses of domperidone for treating lactation insufficiency in mothers of preterm infants – study protocol

BACKGROUND: Mothers of preterm infants face many challenges in establishing and maintaining an adequate supply of breast milk during their infant's prolonged hospitalisation. Domperidone has been shown to be superior to placebo for the treatment of lactation insufficiency, however there is significant uncertainty regarding the optimal treatment dose. This trial has been designed to resolve the issue of whether a higher dose of domperidone (20 mg three times daily; 60 mg/day) leads to greater improvements in maternal breast milk supply compared to a lower dose (10 mg three times daily; 30 mg/day), while also evaluating differences in adverse events. This knowledge will be critical for guiding clinical practice and facilitating benefit versus risk evaluations surrounding the use of domperidone in lactation. METHODS: SUMMIT is a multicentre, double-blinded randomised controlled trial that will assess whether a higher dose of domperidone (60 mg/day) will further increase maternal breast milk supply compared to a lower dose (30 mg/day). Target population are mothers of preterm infants born at less than 34 weeks' gestation, who are between 7 and 28 days postpartum, with lactation insufficiency, and can give informed consent. Participants will be randomly allocated into two parallel groups in a 1:1 ratio (n = 50 per group) to receive either 60 mg/day or 30 mg/day of domperidone. The primary outcome will be daily expressed breast milk volume over a 24-hour period on Day 21 post randomisation. As part of the main trial, participants and their infants will be followed until the infant reaches term corrected age or is discharged home from the neonatal unit (whichever occurs first). DISCUSSION: This will be the largest clinical trial to evaluate the efficacy and safety of domperidone for the treatment of lactation insufficiency following preterm birth. This trial will provide critical evidence to guide clinical practice recommendations regarding what the optimal treatment dose of domperidone should be, while also enabling assessment of the impacts of different dosage regimens on longer-term breast milk feeding outcomes, as well as maternal and infant health outcomes. TRIAL REGISTRATION: This study was prospectively registered via the Australian and New Zealand Clinical Trials Registry (https://www.anzctr.org.au: ACTRN12621000508875 (registered 30 April 2021)).