Caprogen DS is a synthetic progestin medication containing 500 mg of hydroxyprogesterone caproate per 2 ml. It is primarily used to reduce the risk of preterm labor in women with a history of spontaneous preterm birth. The injection is administered intramuscularly (IM), typically starting between the 16th and 20th week of pregnancy and continued once a week until the 37th week of pregnancy or the onset of labor. Caprogen DS works by stabilizing the uterine lining and preventing premature contractions, helping to extend the pregnancy and reduce the risk of preterm birth.