The role of egg quality and ovarian function in fertility

fertilized eggIt is a fact that all women have a finite number of eggs in their body, which when released during ovulation can be fertilised by sperm to produce a child. However, many people mistakenly believe that the number of eggs a woman has is all that matters when it comes to conception. Unfortunately, that’s not the case.

The fact is that not only does the number of eggs matter but also the quality of those eggs. Will they be healthy enough to develop into a baby? Are there enough chromosomes? Do the eggs have enough energy to split after fertilisation?

calendarEgg quality is greatly influenced by a woman’s age. Women in their 20s and 30s should have a large amount of good quality eggs available for fertilisation. Yes, there will be a few ‘bad’ eggs, but this is normal; however, as a woman ages, the quality and quantity of her eggs declines and the number of poor quality eggs may eventually be higher than the good ones. Underlying genetic reasons may also cause this decline in quality.

The ovarian reserve test

During fertility treatments such as in vitro fertilisation (IVF), where the ovaries are stimulated to produce more eggs for collection, some women – even with regular periods – may perform sub-optimally. This means that instead of releasing 8-10 eggs, their ovaries may only release 2 or 3. This is usually an indirect reflection that their ovaries are not performing as they should.

Together, the quantity and quality of a woman’s eggs is known as her ovarian reserve, which plays a critical role in how IVF treatment will work. In the past, it was a challenge to assess how a woman would respond to IVF treatment, but in the last decade, new tests have been developed that are quite accurate. This test is known as the ovarian reserve test, which involves an internal scan and a blood test.

The internal scan determines the number of egg sacs that are in the ovaries. Based on the egg sac count, doctors are able to tell whether ovarian function is compromised. Typically, each ovary should contain 5 or 6 egg sacs. The blood test determines how responsive the ovaries may be based on follicle stimulating hormone (FSH) and anti-Mullerian hormone (AMH) levels.

The ovarian reserve test helps to determine the type of fertility treatment required. In younger women that have good ovarian function and good quality eggs, simpler treatments such as insemination will be used at first. In cases in which ovarian function is compromised, it may be best to fast-track fertility treatment right into the IVF route.