Stimulation of Follicle Production

IVF Step 2: Stimulation of Follicle Production

You will be given drugs to encourage the formation of follicles in the ovaries.  These are given by injection and the nurses will discuss how these drugs are given.   If you are taking down regulated drugs, you will need to carry on taking these throughout the stimulation process. This helps ensure the ovaries respond in a controlled and predictable way during stimulation.

A follicle is simply an immature egg, surrounded by a sac of fluid, which develops within the ovary.  As the follicle develops it grows until it is 18 to 20 mm when the egg is mature.  It is at this size that the follicle will be triggered by hormones from the pituitary gland to rupture and release the egg (ovulate). In IVF, medication carefully controls this process to prevent premature ovulation. Many patients wonder how fast follicles grow; growth rates can vary depending on age and ovarian reserve.

During the IVF cycle, drugs are given to encourage the development of follicles in the ovary.   The drugs do however stimulate the ovaries to produce more follicles than would normally grow in a menstrual cycle.  The number of follicles that develop depends on many factors, including your age and the hormone test results.   An average patient will hopefully get 8 to 10 follicles.   Drugs are administered by daily subcutaneous injections.  The nurses will give you all the information that you need to perform the injections.  These medications help support the growth of multiple follicles so more mature eggs can be collected.

Your drug regime will be personal to you, taking into account the results of your blood tests. It is vital that you ask the nurses if you are not sure about the dose or the injections, as if you make a mistake it can be difficult to rectify. Following your personalised dose closely helps maximise your ovarian response and treatment safety.

Common Drugs on a Short Protocol

How will I be monitored to ensure I am responding to the drugs appropriately ?

All parts of your cycle will be closely monitored using vaginal ultrasound scanning techniques.  A probe, called a transducer is placed into the vagina.   The probe is covered with a condom to reduce infection and a gel for lubrication.   The probe sends out sound-waves which reflect off the body structures.  A computer receives these waves and uses them to create a picture of the uterus and ovaries.   The scan is painless and safe. Regular scans help track follicle size, number and the thickness of the womb lining.

After approximately 8 and 10 of stimulation injections we will perform your first monitoring ultrasound scan. Earlier monitoring may be undertaken where the patient’s clinical circumstances indicate that this is required, including where there is an increased risk of an excessive response to medication.   We will count and measure all the follicles seen and measure the endometrium, the lining of the womb.   The dose of stimulation drug may be changed depending upon the response by the ovaries.   A nurse will discuss your progress with you after the scan and answer any queries you may have. This monitoring helps ensure your response remains safe while giving the best chance of developing mature eggs.

Page Last Modified: 14th September 2026