Tocolytics are medicines that attempt to stop labor. They are used if labor begins before term. Tocolytics can stop labor or delay labor to give the baby's lungs time to mature. If started early in premature labor, they may be effective. They are not as successful later in labor, if the membranes have broken, or if your cervix is already dilated beyond 2 centimeters. When taking this medication, you may need hospitalization or home therapy.

Terbutaline, ritodrine, nifedipine and magnesium sulfate are all used as tocolytic drugs. Tocolytics are not used if the mother has chorioamnionitis (an infection in the membranes around the baby), abruptio placenta, severe preeclampsia or eclampsia, cardiac disease, or other severe medical illnesses. Tocolytics are also not used if the fetus has died in the uterus, or if the fetus is in acute distress. Some of these drugs are used in combination with other medications.