Purpose of review: The preterm birth rate in the United States remains at an all-time high and continues to rise. Acute tocolysis has potential to delay preterm birth for 48 h, the critical period of antenatal steroid administration, or to arrest an episode of preterm labor, thus delaying birth and improving neonatal outcomes. It is therefore paramount that medical providers remain up-to-date regarding the usefulness, indications and contraindications, and side-effects and adverse effects of all tocolytics.
Recent findings: Magnesium sulfate remains the most common tocolyic agent in the United States. Recent evidence comparing oral nifedipine with magnesium sulfate suggests equal efficacy with fewer maternal side-effects, thus supporting this oral medication as first-line treatment. This review will summarize the most common acute tocolytic drugs, their methods of action, and clinical data regarding their utility.
Summary: All tocolytic medications have side-effects, some of them potentially life-threatening. Decisions regarding whether to use a tocolytic and which tocolytic to use require the diagnosis of preterm labor, knowledge of the patient's gestational age, medical conditions, and cost. Once tocolysis is initiated, attention must be paid to the patient's response, side-effects, and adverse events. Larger studies are needed which incorporate, in addition to efficacy, data on safety and side-effect profiles and cost.