LMWH for Treatment of Early Fetal Growth Restriction (HepaGrowth)

FGR is the second leading cause of perinatal mortality, being associated with approximately 30% of stillbirths. Early FGR is associated with substantial disturbances of placental implantation and fetal hypoxia, which requires fetal cardiovascular adaptation. Both maternal and fetal Doppler alterations are present, allowing for risk stratification and monitoring. Although the precise etiology for FGR due to placental causes is unknown, placental thrombosis, infarcts and hypercoagulability are frequently seen, suggesting a role for the activation of the coagulation cascade in the genesis of FGR. Currently, the management of early FGR is limited to the monitoring of fetal Doppler parameters until the risks for preterm delivery outweight the benefits of ongoing monitoring. As such, there is a special need for effective preventive and therapeutic interventions that improve the outcomes. Low molecular weight heparin (LMWH), for its anticoagulant and anti-inflammatory properties has been suggested as a possible therapeutic agent in this setting. The investigators will randomize the participants to two intervention arms in a one-to-one ratio, using a computer generated randomization program. The randomization will be stratified for gestational age at diagnosis of FGR (22 to 26 weeks and \>26 to 32 weeks). The experimental group will be administered enoxaparin subcutaneous injections (40 mg, 4000 IU daily) and the control group will be provided standard of care. Both groups will start intervention immediately after the diagnosis of FGR, and will continue it until 36 weeks of gestation or 12 hours before delivery, whichever comes first.