Melatonin and Perinatal Outcomes in MVM-Related Fetal Growth Restriction (MIMVMFGR)

The goal of this clinical trial is to evaluate the efficacy and safety of melatonin in the treatment of early-onset severe maternal vascular malperfusion-related fetal growth restriction (MVM-FGR), and to determine its effects on fetal growth and perinatal outcomes. The study will enroll pregnant women with singleton pregnancies diagnosed with severe MVM-FGR between 24+0 and 31+6 weeks of gestation. The main questions it aims to answer are: * Whether melatonin treatment can reduce the incidence of a composite adverse neonatal outcome, including neonatal death and severe neonatal complications. * Whether melatonin treatment can improve pregnancy and neonatal outcomes, including the interval from treatment initiation to delivery, gestational age at delivery, fetal growth trajectory throughout pregnancy (Z-score slope over time estimated using linear mixed models), neonatal birthweight, Apgar scores, neonatal complications (such as respiratory distress syndrome), maternal adverse events (such as hypertensive disorders of pregnancy), and placental pathological findings. Researchers will compare participants receiving a placebo (one capsule taken at bedtime, identical in appearance and size to melatonin) with those receiving melatonin to determine whether melatonin improves these maternal and neonatal outcomes. Participants will: • Take melatonin 10 mg orally once nightly at bedtime.