OBJECTIVE:: To assess the economic consequences of immediate delivery compared with expectant monitoring in women with preterm non-severe hypertensive disorders of pregnancy. DESIGN:: A cost-effectiveness analysis alongside a randomised controlled trial (HYPITAT-II). SETTING:: Obstetric departments of seven academic hospitals and 44 non-academic hospitals in the Netherlands. POPULATION:: Women diagnosed with non-severe hypertensive disorders of pregnancy between 34 and 37 weeks of gestation, randomly allocated to either immediate delivery or expectant monitoring. METHODS:: A trial-based cost-effectiveness analysis was performed from a healthcare perspective until final maternal and neonatal discharge. MAIN OUTCOME MEASURES:: Health outcomes were expressed as the prevalence of respiratory distress syndrome, defined as the need for supplemental oxygen for >24 hours combined with radiographic findings typical for respiratory distress syndrome. Costs were estimated from a healthcare perspective until maternal and neonatal discharge. RESULTS:: The average costs of immediate delivery (n = 352) were €10 245 versus €9563 for expectant monitoring (n = 351), with an average difference of €682 (95% confidence interval, 95% CI −€618 to €2126). This 7% difference predominantly originated from the neonatal admissions, which were €5672 in the immediate delivery arm and €3929 in the expectant monitoring arm. CONCLUSION:: In women with mild hypertensive disorders between 34 and 37 weeks of gestation, immediate delivery is more costly than expectant monitoring as a result of differences in neonatal admissions. These findings support expectant monitoring, as the clinical outcomes of the trial demonstrated that expectant monitoring reduced respiratory distress syndrome for a slightly increased risk of maternal complications. TWEETABLE ABSTRACT:: Expectant management in preterm hypertensive disorders is less costly compared with immediate delivery. : Expectant management in preterm hypertensive disorders is less costly compared with immediate delivery.