When the follicles are 18-19mm in diameter, ovulation injections can be given to promote the rupture of the follicles. It is very important to choose the right time to inject the ovulation medication, as it is not appropriate to inject when the follicles are too small or too large. If the follicles are too small, the immaturity of the follicles will affect the normal conception. If the follicles are too large, luteal cysts will easily form after rupture. Therefore, for ovulation injections, the follicles need to be monitored by ultrasound and then injected after they are suitable. The commonly used egg-breaking injection is an injection of chorionic gonadotropin, a glycoprotein that promotes the final maturation of the oocyte and ovulation occurs within 1-2 days after the injection of the drug.