IVF requires numerous eggs compared to a natural cycle which only requires one. This is because some of the eggs used in an IVF cycle will be damaged during the ART procedures and others will not fertilize and develop.
To produce the number of eggs needed for IVF, and to appropriately time egg release, IVF patients are started on fertility drugs (Lupron, Antagon, Cetrotide) designed to suppress their own hormones (FSH and LH). FSH is administered by injection and directly stimulates the ovaries to recruit and develop numerous follicles, each of which contains an egg. Drugs like Lupron are critical to a successful cycle as they "block" natural ovulation. Otherwise, ovulation may occur prior to egg retrieval resulting in a "lost IVF cycle". While on these drugs, ovulation must be induced by the drugs hCG or LH.
The progress of the IVF cycle is monitored by ultrasound scans of the ovary. Our Long Island IVF program has the latest monitoring equipment. As the follicles develop, the number and size can be measured using transvaginal ultrasound. As healthy follicles develop in an IVF cycle they produce increasing levels of estrogen, which is monitored by blood tests. Estrogen levels are used to help determine the appropriate dosage of FSH and to avoid potential side effects, such as ovarian hyperstimulation syndrome.
Once the follicles, developed during the IVF cycle, are judged to be mature, an injection of hCG is given to initiate the final phase of egg development. Sufficient development and an adequate number of eggs must be present in order to proceed to retrieval.