Preterm labour is a common obstetric problem and a major cause of perinatal mortality. The exact cause of preterm labour remains unclear and there are many risk factors as socioeconomic status and life style factors of the mother. Three main interventions play an important role in the management of preterm labour, tocolytic therapy, antibiotics and corticosteroids. The maternal and fetal side effects of tocolytic therapy are important considerations. Assessment of fetal umbilical and middle cerebral artery Doppler parameters before and after tocolytic therapy was carried on in this study. The prevention of preterm birth depends mainly on identification of women with risk factors and early intervention.