Introduction
Preterm labor is one of the most important problems in pregnancies, and it can have serious consequences, such as premature birth and its complications (1, 2). In the past, fetal mortality was high in preterm labor. However, these days, with the identification of these pregnancies and proper care of the mother and fetus, the fetal mortality rate in these pregnancies has been reduced; but even so, further research is needed (3, 4). Premature birth, in addition to causing economic, psychological, and psychological problems in the family, also results in the loss of financial and human resources (5). It has received special attention in recent years because it is a painful and stressful experience for both infants and parents(6). Premature infants are readmitted at a rate of 11 per 1000 live births that were alive three months after discharge, which is significantly higher than the rate for term babies (7). Given that a decrease in infant mortality rates indicates an improvement in public health (8), measures  to reduce the number of preterm births are especial important factors (9). Nowadays, treatment methods such as taking progesterone orally or injecting it, or taking drugs with vasodilating properties such as Nifedipine, are common (10, 11), but determining the most effective treatment in this field necessitates research. It is a clinical trial with a comparative intervention. For many years, magnesium sulfate has been known to be effective in this field(12); Magnesium sulfate, chemically known as MgSO4, is an injectable drug with clinical applications that include seizure prevention in preeclampsia, preterm labor, and, on rare occasions, the treatment of cardiac arrhythmias. Both the injectable and oral forms are used to treat hypomagnesemia, as well as bronchodilators and osmotic laxatives. Its cellular effect was mediated by inhibiting the release of acetylcholine at the nerve-muscle junction, thereby inhibiting calcium entry into cells due to increased intracellular magnesium. Its anticonvulsant effect is due to the blocking of calcium neurons via the glutamate duct (which is only found in the CNS) and its anticonvulsant effect on the cerebral cortex without causing CNS depression in the mother and fetus. Indomethacin is also available in pill, capsule, and suppository form as a nonsteroidal anti-inflammatory drug (NSAID). Indomethacin is a powerful analgesic and anti-inflammatory drug that is also used to prevent uterine contractions. Indomethacin works by inhibiting the enzyme cyclooxygenase to convert arachidonic acid to prostaglandin. Prostaglandins play a significant role in both term and preterm labor. Despite extensive researchs, no single drug has been introduced as the first line of treatment, and the choice of drug is based on drug availability, effectiveness, maternal and neonatal complications, and drug price. Due to the huge importance of the subject in this study, the effect of Magnesium Sulfate and Indomethacin suppository with the administration of Magnesium Sulfate alone in inhibiting preterm delivery in women aged 24 to 32 weeks at Kosar Hospital in Qazvin in 2019 and 2021 years was compared.