The quality of a woman’s egg plays a key role in her fertility and her ability to have a baby. High-quality eggs have the best chance of developing into an embryo, implanting in the uterus, and resulting in a successful pregnancy.
Egg quality refers to whether an egg is chromosomally “normal” (euploid) or “abnormal” (aneuploid). A chromosomally normal egg has 23 chromosomes and when fertilized by the sperm, which also has 23 chromosomes, the resulting chromosomally normal embryo will have a total of 46 chromosomes.
Age and Egg Quality
As a woman’s ovary ages, she will have increasing numbers of aneuploid eggs which contain too few or too many chromosomes. If conception occurs with an aneuploid egg, the embryo will inherit too few or too many chromosomes. Most aneuploid embryos will either fail to implant in the uterus or will result in miscarriage. In some instances, the aneuploid embryos may result in chromosomal disorders, such as Down syndrome, extra copy of chromosome 21.
The best indicator of egg quality is a woman’s chronological age. At the age of 25, 75% of a woman’s eggs are chromosomally normal. At 35 years of age, about 50% of a woman’s eggs are chromosomally normal. By the time a woman reaches 40, about 10-15% of her eggs are chromosomally normal.
A woman is born with all of the eggs she’ll ever have (approximately 1 to 2 million). The eggs (in the form of follicles) are contained within the ovaries at different stages of development and diminish in quantity and quality over time. By the time she reaches puberty, she will have around 300,000 potential eggs in her ovarian reserve. During her reproductive years, only a few hundred eggs will actually be ovulated.
Based on your age, medical history, and the results of your ovarian reserve testing (described below), our fertility specialists can assess how well you will respond to ovarian-stimulating drugs and we can build a fertility treatment care plan that’s personalized for your unique needs. Remember, it only takes one quality egg and sperm to create an embryo!
Ovarian Reserve Testing
The following blood tests and ultrasound can help us determine if you are ovulating and your overall fertility potential.
Follicle Stimulating Hormone (FSH)
On the third day of the menstrual cycle, we can take a blood sample to analyze the hormone FSH, which is critical to follicle development. FSH is the way that the pituitary gland in the brain communicates with the ovaries. It signals the ovaries that it is time to make an egg each month. As the eggs decrease in quality, they are more resistant to FSH and it takes more and more FSH to keep the cycle progressing. Therefore, the higher the FSH value, the lower the quality of the eggs.
E2 is the companion to FSH and is the ovaries’ method to communicate with the brain. E2 levels increase as an ovarian follicle becomes stimulated and is increasing in size. For evaluation and to ensure the validity of the FSH value, the estradiol level should be under 50 pg/ml. If it is elevated above 50 pg/ml early in the cycle, the ovaries are responding early, and egg quality is potentially decreased.
Anti-Mullerian Hormone (AMH)
AMH is a glycoprotein released by the granulosa cells of early developing eggs that help protect and mature the eggs. Over a lifetime, as the number of eggs decreases, the granulosa cells decrease and AMH decreases. AMH gives an estimate of the total number of eggs that are remaining in the ovaries.
A transvaginal ultrasound allows us to assess resting/antral follicle count (AFC). The ultrasound usually takes place between days three to twelve of your period and is performed by counting the total number of follicles between four and nine millimeters in both ovaries. These are eggs which could potentially mature and be ovulated. A smaller number of follicles means you may have problems with egg quality and quantity.
Women that that aren’t ready to have children but are interested in having them in the future, can preserve their fertility through egg freezing (also known as oocyte vitrification, oocyte cryopreservation, and/or fertility preservation). After taking ovarian stimulating medication, the maturing eggs inside the ovaries are retrieved, frozen, and stored until you choose to use them.
Egg freezing when your eggs are of higher quantity and quality, gives you a greater chance of having a successful pregnancy later on in life.
To learn more about the egg freezing process, visit our Egg Freezing page.
Egg Quality Research
CCRM’s research team is continuously finding new ways to improve egg quality for our patients. The following CCRM clinical studies are currently underway on egg quality:
You might also be interested in: Embryo Quality & Fertility.