[MEDICAL THERAPY FOR THE MANAGEMENT OF PRETERM LABOR: IS THERE A FIRST LINE AGENT?]

Preterm birth is defined as delivery before 37 weeks. It is the leading cause of perinatal morbidity and mortality. Spontaneous preterm birth accounts for approximately 70% of all preterm births. Postponing delivery for 48 hours in order to allow administration of corticosteroids, magnesium for neuroprotection and in order to transfer women to a center with neonatal intensive care unit are the goals of tocolytic therapy. The benefits of tocolytic therapy between 24.0 and 34.0 weeks of gestation outweigh the risk of maternal and fetal complications and it should be initiated provided no contraindications exist. Tocolytic agents that have been used are: prostaglandin synthetase inhibitors, calcium channel antagonists, B-adrenergic agonists, magnesium and oxytocin receptor antagonists. All drugs have demonstrated limited benefit that consists mainly of prolonging the gestational age for 48 hours, without a reduction in the incidence of perinatal mortality and morbidity. Additionally, most available tocolytic agents carry inherent risks of adverse effects. According to the American College of Obstetricians and Gynecologists recommendations, there is no clear first line tocolytic drug to manage preterm labor. Other subjects of debate related to the use of tocolytic therapy include: The effectiveness of combination therapy, the use of tocolytic therapy in multiple pregnancies and the use of progesterone as an adjuvant therapy. We will address the efficacy and tolerability of the tocolytic agents available, the issue of maintenance therapy and debates mentioned above, and try to suggest a first line tocolytic agent based on a study performed at our institution.