 While there is no evidence that primary tocolytic agents such as magnesium sulfate or beta-agonist drugs prolong pregnancy extensively when compared to placebo, preterm labor and early delivery remain one of the top few health problems in the perinatal field. For that reason, investigations to compare available first line agents are warranted. Based on the current information in the literature calcium channel antagonists and anti-prostaglandin drugs are the best hope to treat acute preterm labor in an effort to significantly prolong pregnancy with the fewest adverse effects on mother and baby. 