Steps of IVF process 1. controlled ovulation 2. follicle monitoring 3. egg retrieval 4. sperm retrieval 5. in vitro fertilization 6. embryo in vitro culture 7. embryo transfer 8. progesterone supplementation after embryo transfer 9. morning urine test on day 14 after embryo transfer to determine pregnancy 10. ultrasound to check the number of fetuses and embryo implantation site 14 days after pregnancy Controlled ovulation: Since the length of natural menstrual cycle varies from person to person, it is not easy to schedule egg retrieval. Moreover, only one dominant follicle develops in the natural cycle, and only one embryo can be formed after fertilization, and the pregnancy rate of transferring one embryo is very low. Therefore, controlled superovulation is needed to enhance and improve ovarian function in order to obtain multiple healthy eggs regardless of the natural cycle, to provide multiple embryos for transfer, and to synchronize the corpus luteum development with the endometrial function as much as possible. Controlled ovulation usually involves the use of GnRHa to bring down the FSH and LH in the body, followed by the administration of HMG or FSH ovulation drugs to stimulate the growth of follicles in the ovaries, with the dosage of the drugs adjusted according to the patient’s responsiveness to the drugs. Follicle monitoring: To evaluate the effect of ovarian stimulation and to determine the timing of egg retrieval, the follicle size should be monitored by vaginal ultrasound and the E2 value (estrogen) should be checked with blood sampling to adjust the dosage of medication. When two to three or more follicles are larger than 45px in diameter and the number of follicles above 35px is comparable to the E2 value, human chorionic gonadotropin (hCG) can be injected to promote follicle maturation. The eggs are retrieved 34 to 36 hours after hCG injection. Egg retrieval: The most commonly used method of egg retrieval is under local anesthesia, guided by vaginal ultrasound, and the needle is passed through the vaginal vault to the ovaries where the eggs are immediately transferred under a microscope to a Petri dish containing embryo culture medium and incubated in a 37 °C incubator. Sperm retrieval: The sperm is retrieved on the same day as the egg retrieval. Hands are washed before sperm retrieval and semen is retained by the masturbation method. The small cup given is sterile and the rim and the inside of the cup should not be touched during the retention. The extracted semen is processed by the upstream method or Percoll density gradient centrifugation. In vitro fertilization: The treated sperm and eggs are placed in the same Petri dish 4-5 hours after egg retrieval and co-cultured for 18 hours before fertilization can be observed under a microscope. If the sperm quality is too poor to allow natural fertilization, fertilization must be forced by microinjection (refer to intracytoplasmic single sperm microinsemination). Embryo transfer: The fertilized egg is cultured in vitro for 48 to 72 hours to develop into an 8 to 16 cell stage embryo. At this time, the number of embryos to be transferred is determined by the patient’s age, previous pregnancy and the quality of the embryos. Embryo transfer generally does not require anesthesia. Currently, most embryos are transferred 2 to 3 days after fertilization, and some centers use 3 to 5 days after fertilization for embryo transfer. Delaying embryo transfer requires higher conditions for in vitro culture, but delaying transfer is more in line with pregnancy physiology and also eliminates inferior embryos through natural screening, which can improve pregnancy rate and reduce the rate of multiple births. Hormone supplementation after embryo transfer: Currently we mostly use injections to give progesterone to support the corpus luteum. If pregnancy is confirmed, hCG is switched to continue supplementation until 10 weeks of pregnancy. Pregnancy can be determined by a urine test or blood draw 14 days after embryo transfer.