The main ingredients of the injection include chorionic gonadotropin injection and progesterone injection, which are usually used in cases of preterm miscarriage in the early stages of pregnancy, manifested by mild abdominal pain, bleeding, and progesterone levels below normal. The injection should be used under the guidance of a doctor and will not cause any adverse effects on the fetus and the mother. Pregnant women who have symptoms of preterm miscarriage such as bleeding and abdominal pain in early pregnancy need to be treated with intramuscular injections of birth control. The progestin in the birth control injection can reduce the excitability of the uterus during pregnancy and inhibit smooth muscle contraction, which provides for the early growth of the fetus, thus achieving the purpose of fetal preservation. Generally, the fetal preservation injection is injected in the location where the buttock muscles are abundant to avoid causing nerve and blood vessel damage. The length of injection is usually decided on a case-by-case basis, and is maintained for 1-2 days after the symptoms of pre-eclampsia have subsided, or the injection can be stopped according to the doctor’s instructions. Chorionic gonadotropin injection and progesterone injection are mostly used in the early pregnancy stage for fetal preservation treatment, and magnesium sulfate or ritodrine is often used in the middle of pregnancy. A clear diagnosis is needed before administration to avoid adverse effects. In case of preterm miscarriage due to poor quality of embryo or genetic abnormality, the birth control injection will not be able to provide a better treatment. During the period of pregnancy prevention, pregnant women need to maintain a good living condition, pay attention to rest, take adequate nutrition and have regular medical check-ups. Under the guidance of the doctor, she should take the medication and review the progesterone, HCG value and ultrasound regularly to ensure the normal development of the fetus.