Chorionic gonadotropin injection refers to the injection of chorionic gonadotropin, which has a variety of effects, and in order to achieve a therapeutic effect, this drug has a requirement for the timing of its application, i.e., there is a time limit. When this drug is used to promote ovulation, it needs to be applied when the follicle is mature. Since ovulation usually occurs within 36 hours after injection, it can increase the chances of conception. If the injection is given too early or too late, the follicles will be underdeveloped or decline, which will affect the therapeutic effect. When used for the treatment of preeclampsia, the drug is usually injected every other day when there are signs of preeclampsia, which has the effect of preserving the fetus. When used to treat progesterone insufficiency, the drug is injected after 15 days of menstruation and is usually discontinued around 11 weeks after pregnancy. After that time, the placenta produces enough chorionic gonadotropin to sustain the pregnancy. It is recommended that chorionic gonadotropin injections be given as prescribed by your doctor.