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What are ovarian follicles?

Ovarian follicles are small sacs filled with fluid that are found inside a woman’s ovaries. They secrete hormones which influence stages of the menstrual cycle and women begin puberty with about 300,000 to 400,000 of them. Each has the potential to release an egg for fertilisation. Follicles and their size and status are a vital part of assessing fertility and fertility treatment.

An evaluation of follicles involves a pelvic ultrasound scan of your womb and ovaries as well as an Anti-Mullerian Hormone blood test. The pelvic ultrasound scan will assess the size and number of follicles present on your ovaries called an Antral Follicle Count.  The results of this scan as well as your blood test will allow a fertility specialist to assess your fertility and therefore your ability to conceive.

How may eggs will there be in a follicle?

In a normal menstrual cycle one follicle will grow containing one egg. The follicle will get bigger until it ruptures at ovulation which then releases the egg. This is usually around 14 days after the beginning of your menstrual cycle.

Will all follicles release an egg?

Usually, yes. In most cases follicles will release an egg. However, whether the egg is mature enough or is of good enough quality for fertilisation is another matter.

How many follicles is normal?

This is relevant to the woman’s age, general health, and lifestyle. However, more follicles do not necessarily guarantee successful fertilisation. The quality of the eggs is key and many women with fewer follicles can still conceive successfully with IVF because of the quality of the eggs.

How many follicles are left at 30?

The quality and quantity of a woman’s eggs is affected by her age as well as other health and lifestyle issues. The number of ovarian follicles a woman has does decline with age and so does the quality of her eggs. After the age of 35 however, a woman’s fertility starts to decline significantly, and by her early to mid-forties the chances of achieving a successful pregnancy are slim.

How do follicles relate to my chances of having a baby?

There are two main factors to consider when it comes to female virility:

  • Egg Quality
  • Follicle Count

The number of follicles present within your ovaries will tell a fertility specialist about the state of your fertility. This is because follicles contain immature eggs. These immature eggs develop and grow in size until the follicle they are held in is of optimum size, whereupon they are released (ovulation). If you have lots of follicles, then you have the potential to release more eggs increasing the chance that one of those eggs will be healthy enough to result in a successful pregnancy.

Egg quality is determined by your age and also your lifestyle. As a woman get older, the quality of eggs decreases, particularly after the age of 35, and normally from around her mid-40s most women will not be able to conceive naturally. Unfortunately, it is not possible to test the quality of your eggs.

If you are keen to understand your chances of having a baby, we would suggest a Fertility MOT.

Why happens to my follicles during IVF?

During IVF, you will be put on a course of drugs to stimulate your ovaries to produce more eggs. Monitoring the ovarian follicles is part of the fertility treatment process. You will have several pelvic ultrasound scans during the stimulation phase to assess that the dosage of medication is correct and when you are ready for or egg collection. This includes monitoring the number and size of the follicles on each ovary.

When your follicles have reached around 18-20mm in diameter they are deemed ready for egg collection. You’ll be given a hormone trigger injection to stimulate your follicles to release the mature eggs that have been prepared in your follicles. We will time your egg collection procedure around 36 hours after your trigger injection to allow us to collect your eggs at the best possible time. The mature eggs that are collected will then be transferred to the laboratory to be fertilised with sperm to create embryos.

Can my follicles be affected by IVF?

Ovarian Hyperstimulation Syndrome may occur if the ovaries are very sensitive to stimulation and produce an unusually large number of follicles and therefore eggs (usually more than 15) or high levels of oestradiol. This is a potentially dangerous situation, although OHSS, in its severe form, occurs in only 0.5% of patients. During the simulation phase of your treatment cycle, your follicles will be closely monitored by ultrasound scans. If we think you are at risk of developing severe OHSS, there are a number of options that you and your fertility specialist will need to consider including abandoning the cycle, delaying the egg collection, or freezing all the embryos for transfer in a later cycle.

What is Polycystic Ovarian Syndrome?

Polycystic ovarian syndrome (PCOS) is a condition which affects how the ovaries work. It usually means cysts can be seen on the ovaries or high levels of (male) hormones in the body can prevent the ovary from releasing an egg.

PCOS is very common and can affect up to one in every five women. Symptoms of PCOS can include irregular or no periods, difficulty getting pregnant, hair growth, weight gain and acne. Although PCOS cannot be cured it can be treated by losing weight or through medication. If you are trying for a baby, there are many options to help you to conceive including medication, Intrauterine Insemination (IUI) or IVF. In most cases women with PCOS can get pregnant.

More questions about your own fertility?

If you’re curious about your fertility or want to find out where you are in terms of your overall chances to conceive, why not book a female Fertility MOT with us now. It’s as easy as using our form or calling us on 020 7563 4309.


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