Cor-9 500 mg Injection 2 ml is used to prevent premature labour. It contains Hydroxyprogesterone, which modulates the immune response of pregnant women to prevent rejection of the embryo and allow its attachment to the uterus. It prevents miscarriage and helps lower the risk of premature birth in pregnant women who have had past premature labour. In some cases, you may experience certain common side effects such as nausea, vomiting, itching, hives (skin rashes), swelling in the face, lips, tongue, or throat, and diarrhoea.