We used this model to compare costs and benefits between standard care and LDA treatment. The first branching of the model separates pregnancy outcomes into mutually exclusive branches of term birth, preterm birth, and perinatal death. Term or preterm infants who died within 7 days of birth were not included in the term or preterm branches. When we ran this model for our LDA-treated sample, we reduced preterm birth and perinatal death per the relative risks reported in the ASPIRIN trial.4Subsequent branches account for infant health-care use with hospitalisations and associated therapies, assuming receipt of a given therapy included receipt of all lower-intensity therapies. All branches are mutually exclusive, resulting in 15 different scenarios. CPAP=continuous positive airway pressure. LDA=low-dose aspirin.