Objective:To determine the efficacy and safety of oral nifedipine a tocolytic agent in the management of preterm labour and to determine whether nifedipine as a tocolytic can improve neonatal outcome.Design:Prospective observational study. Setting:Kerala Institute of Medical Sciences, Thiruvananthapuram, a tertiary care hospital in Kerala, South India.Population: Women admitted with preterm labour between 24 and 36 completed weeks of gestation. Methods:Women admitted with Preterm labour was given Nifedipine 30 mg followed by 10mg 6th hourly for 48 hours. Antenatal steroid coverage with Betamethasone also given.Preterm labour progression monitored with uterine contractions, cervical effacement and dilatation. Maternal parameters-headache, palpitation, dyspnoea, tachycardia, tachypnoea, hypotension and fetal parameters-fetal bradycardia, fetal tachycardia was monitored. Women were then followed up till delivery and duration of pregnancy prolongation noted. Data was collected regarding the neonate- birth weight, Apgar at 5 minutes, need for resuscitation, need for ventilatory support, neonatal complications and duration of hospital stay. The data collected using the predefined proforma was entered into MS Excel and analysis done using the statistical software for social sciences, SPSS version 16.0.All the quantitative data was expressed as mean +/- standard deviation and the qualitative data in frequencies (n) and percentages (%). All the continuous variables were compared using chi square test. A p value of <0.5 was considered significant.Main Outcome Measures:Efficacy of nifedipine as an acute tocolytic in preterm labor was assessed in terms ofprolonging pregnancy for 48 hours with antenatal steroid coverage.Safety was assessed in terms of maternal side effects and neonatal morbidity.Results:69.2% of cases between GA24-27 weeks, had pregnancy prolongation of >/= 2 days, where as it was 97.4% for GA between 28-32 weeks and 97.1% for GA between 33-36 weeks. A p value of 0.001, showed statistical significance. A total of 52% had their pregnancy prolonged beyond 7 days, 42.7% had their pregnancy prolonged beyond 2 days but within 7 days, 1.3 % delivered between 24hrs and 48 hrs. and 4 % delivered within 24 hrs. of starting the initial dose of nifedipine. The primary objective of prolonging pregnancy >/= 48hrs was achieved in 94.7% of cases.The mean duration of prolongation of pregnancy was 16.41 days.93.3% of cases had antenatal steroid coverage with the standard protocol of betamethasone 12 mg, 2 doses 24 hrs. apart.38.5% of those with GA on admission between 24-27 weeks had GA at birth >34weeks.This was 50% for GA 28-32 weeks.Among the 75 cases, 56% delivered between 35 weeks and 36 weeks, 22% between 33 weeks and 34 weeks, 8% between 31weeks and 32 weeks, 6.7 % between 29 and 30 weeks, only 4% went beyond 36 weeks, and 2.7% between 27 and 28 weeks.The mean gestational age at birth was 35.2 weeks +/- 2.68. Only 46.2 % of GA 24-27 had birth weight >2.5kg.This was 65.8% for GA 28-32 and 85.7% for GA 33-36.P value of 0.018, showed significant association. Apgar at 5 minutes >7 was 69.2% for GA 24-27, 97.4% for GA 28-32 and 100% for GA 33-36 weeks.P value of 0.00, showed significant association.Neonatal hospital stays <4 days was only 38.5% for GA 24-27, 86.8% for 28-32 and 88.6% for 33-36.P value of 0.002 showed significance.No neonatal complication was 53.8% for GA 24-27, 81.6% for GA 28-32 and 85.7% for 33-36.P value of 0.048 showed significant association. 30.8 percent neonates with GA 24-27 required ventilatory support. This was 2.6 percent for GA 28-32 and none in GA 33-36 weeks.Conclusion:Nifedipine is a safe and effective drug for acute tocolysis (for 48 hours) in women with preterm labor.The 48 hours gained, is time well spent in achieving antenatal steroid coverage.Nifedipine by prolonging pregnancy probably improves neonatal outcome. This finding has a definite association with gestational age at admission and the more advanced the gestational age at admission, better is the neonatal outcome.