How many eggs am I going to get? What happens to follicles during IVF?
Follicles are small, fluid-filled sacs in your ovaries. Inside each follicle is an immature egg, which grows and increases the size of the follicle as it grows. The egg is released when the follicle reaches the optimum size, this is when ovulation occurs.
In IVF, your ovaries are stimulated to make the follicles grow and produce mature eggs. Ultrasound scans will tell us when your follicles have grown to the right size, and how many follicles have grown. You’ll be monitored throughout stimulation to ensure that your ovaries are responding as they should and so that any changes can be made to your meds/flowsheet.
When your follicles are ready and are at the right size – around 18-20mm – you’re given a Trigger shot. This makes your follicles prepare to release the mature eggs. We time your egg retrieval procedure in our clinic for just before this happens.
How many follicles do I need for IVF?
Follicle response will vary, but it’s important to remember that if you have a good number of follicles it doesn’t necessarily mean that you have a higher chance of success. What matters most is the quality of the eggs produced. It only takes one egg to make a baby. This is why some women who only produce a few follicles still have a successful IVF cycle.
On average, the number of follicles produced in a cycle is around 10-14, but results vary dependent upon your personal response to stimulation and other factors such as your age and medical history. Follicles do not all start at the same size nor do they all grow at the same speed so IVF ovary will have follicles of many different sizes. For most women follicles between 15-22mm in size will give us a mature egg 80% of the time when we perform an egg retrieval procedure. Some women will only have mature eggs from larger follicles and some will have mature eggs from smaller follicles.
No one is the same. So we have variable-sized follicles, with variable maturity eggs inside, and not all follicles will “give up” their egg during an egg retrieval.