Which medication can be prescribed to prevent premature labor?

Nifedipine is a medication that is often used to prevent premature labor due to its properties as a calcium channel blocker. By inhibiting the influx of calcium ions into smooth muscle cells, nifedipine helps to relax the uterine muscles, thereby potentially delaying contractions and the onset of labor. This is particularly valuable in cases of preterm labor, as it decreases uterine activity and allows the pregnancy to continue to the optimal term.

Magnesium sulfate is also used in the management of preterm labor, but its primary function is to provide neuroprotection for the fetus and to prevent seizures in the mother, rather than to prevent labor itself. Terbutaline, an agonist of beta-adrenergic receptors, can be used to relax uterine muscles but is not commonly a first-line choice due to potential side effects for both the mother and the fetus. Oxytocin, on the other hand, is typically used to induce or augment labor, making it unsuitable for preventing premature labor.

Thus, nifedipine stands out as the medication specifically used for this purpose, making it the correct answer to the question regarding prevention of premature labor.