In the developed world, preterm birth is the biggest contributor to neonatal mortality and a leading cause of pediatric morbidity. Preterm labor is defined as labor occurring with a potentially viable fetus to 36 weeks 6 days gestation. For statistical purposes, some authorities use 20 weeks gestation or 400 gram birth weight as the lower limit of viability. World Health Organisation has recommended 22 weeks and 500 gm as the lower limit of viability. Preterm prelabor rupture of membranes is defined as spontaneous membrane rupture occurring before 37 weeks gestation (preterm) in the absence of uterine contractions (prelabor). There is no current effective method of stopping established preterm labor. The primary aim in the current management of preterm labor is of optimizing the condition of the fetus and provision of neonatal facilities. Preterm labor and delivery may have physical advantages for the mother. The decision whether to treat preterm labor requires careful balancing of the possible benefit to the fetus of prolonging pregnancy against the possible harmful effect to the mother of any treatment. Survival of the preterm infant is also related to birth weight.