After stimulation of the ovaries (induction), the eggs need to mature. This is also done with injections (needles).  When the follicles containing the eggs reach the desired size, maturation can be performed with one or several types of injections from the navel.  Timing is very important at this stage. The eggs should be collected approximately 35.5 to 36 hours after the egg hatching injections.  

If the expectant mother is young, has a low body weight and a high AMH value, only GNRH agonists are used to avoid ovarian hyperstimulation syndrome. Drugs containing the pregnancy hormone hCG are avoided.  In cases where the use of hCG is not contraindicated, both GNRH agonists and hCG can be used together.