Medications are used within IVF to optimise the chances for successful treatment.
Only one mature egg is released each month naturally (ovulation), and there is a window of about four days when fertilisation can occur. If you have unprotected intercourse around the time of ovulation you have a 20% chance of a natural pregnancy.
For IVF, the ovaries are stimulated to produce multiple eggs for collection. Not all of these eggs will successfully fertilise and not all the resulting embryos will develop in the laboratory.
Before ovarian stimulation, medication is given by self-injection to suspend the body’s natural cycle – this is called down regulation. One of the drugs commonly used is called Buserelin, which is a synthetic form of a hormone that occurs naturally in a woman’s body.
The eggs develop within little sacs called follicles in the ovary. As the eggs mature these can be seen with an ultrasound scan.
To stimulate the ovaries, the woman might receive an injectable medication containing a follicle-stimulating hormone (FSH), a luteinizing hormone (LH) or a combination of both. These medications stimulate more than one egg to develop at a time.
Medications for egg maturation
When the follicles are ready for egg retrieval the woman will take human chorionic gonadotropin (HCG) or other medications to help the eggs mature.
For a successful pregnancy the embryo needs to implant within the lining of the uterus. To help prepare the lining of the uterus to make it more receptive to the embryo, the woman may also be advised to take progesterone.
Everyone is slightly different, so it can take one to two weeks of ovarian stimulation before the eggs are ready for retrieval.
The right time to collect the eggs can be determined by a vaginal ultrasound or a blood test to measure the response to ovarian stimulation medications. Oestrogen levels typically increase as follicles develop, and progesterone levels remain low until after ovulation.