Long-term tocolysis with combined intravenous terbutaline and magnesium sulfate: a 10-year study of 1000 patients

To determine whether long-term intravenous (IV) tocolysis using combined terbutaline and magnesium sulfate is safe and effective.

One thousand consecutive women in preterm labor were treated with combination IV tocolytic therapy. Terbutaline was initiated with an infusion rate of 1.75 micrograms/minute and increased to a maximum of 80 micrograms/minute. Magnesium sulfate was infused at 2 g/hour without any bolus and increased to maintain a serum level of 6.5-7.5 mg/dL. Tocolysis was continued until fetal lung maturity was achieved or delivery occurred.

Combination tocolytic therapy prolonged pregnancy by a mean (+/- standard deviation) of 61 +/- 23.6 days in 751 women with intact membranes and by 20.5 +/- 17.4 days in 249 with ruptured membranes. The longest durations of continuous IV tocolysis were 123 days in a patient with intact membranes and 77 days in one with ruptured membranes. The most common side effects were nausea and vomiting, followed by chest tightness and shortness of breath.

Long-term IV tocolysis appeared to be safe and to have acceptable side effects, allowing patients to receive combined terbutaline and magnesium sulfate until delivery.