Hormonal stimulation of the ovaries is carried out with the hormone gonadotropin. At this stage of IVF, egg maturation is stimulated. As with cycle monitoring, the doctor monitors the number and growth of the follicles by ultrasound scans from about the sixth to tenth day of the cycle. Once several follicles have grown to a certain size, the woman is given an injection of the hormone chorionic gonadotropin, which triggers ovulation.

32 to 36 hours later, shortly before ovulation, the so-called follicle puncture takes place. This is a short surgical procedure. Under ultrasound guidance, the doctor removes the mature eggs from the ovaries using a fine needle. Ideally, between five and ten eggs are then retrieved via the vagina and transferred to a nutrient medium in the test tube. There, they meet the partner's fresh sperm, which was obtained through masturbation. The test tube is then placed in a warm incubator. After just one day, it is possible to check whether the in vitro fertilization has been successful.

If successful, the reproductive physician inserts the eggs into the uterus after one to two days. The embryo transfer is done through a thin, flexible tube inserted through the vagina. This procedure does not cause any pain. If good quality embryos are still present after the transfer, it is possible to freeze these surplus eggs. This so-called cryopreservation saves the woman from further hormonal stimulation and egg retrieval.

After the transfer, the luteal phase takes place in the woman's body, which is hormonally supported by the drug progesterone. It helps the fertilized egg to implant. It takes about two weeks before a pregnancy can be detected by the presence of the pregnancy hormone hCG in the blood or urine.