Fertility: Egg Quality Myths and Truths

One of the most common causes of infertility is poor egg quality. Spend just a few minutes researching online, and you’ll find egg quality listed as one of the most important factors in determining a woman’s fertility. Much of what you might read will be discouraging, especially if you’re over 35 and worried about your chances to get pregnant. On the other hand, the encouraging news is that there’s a great deal that can be done to improve egg quality, especially as part of a program designed and monitored by a fertility expert and or fertility coach.

Optimizing egg quality can – and should – be a vital component of a pre-conception health plan. We’ll discuss that in a moment. For now, let’s start with some important facts about eggs, both quantity and quality.


While men will only start to produce sperm at puberty, the average newborn girl has an average of one million to two million immature eggs. At this point, they’re not really eggs -- just follicles. Most of those follicles will die before a girl hits adolescence through a process known as atresia. By the time a girl has her first period (menarche), she’s got about 400,000 follicles left. With each menstrual cycle, she’ll lose another 1,000 follicles. On average, only one lucky little follicle will develop into a mature egg (or ovum), and make its way down the fallopian tubes.

The average woman has 375-425 menstrual cycles over the course of her lifetime. What does that mean? Out of the one or two million eggs she was born with, only about 400 will fully develop. And of course, only a tiny fraction of those, if any, will become fertilized.

The IVF process changes the numbers. Many IVF treatments involve stimulating the remaining follicles to produce additional eggs during ovulation, increasing the chances for successful fertilization, implantation, and so forth. Fertility specialists will often run tests to determine a woman’s ovarian reserve: that is, how many extra follicles are available. A woman with a lower number of extra follicles may be described as having diminished ovarian reserve. Women with diminished ovarian reserve can go on increase their follicle count, improve their overall egg quality and give birth to a healthy baby; a knowledgeable fertility counselor or coach can explore many natural and effective alternative options with you.


As important as egg quantity is, egg quality is perhaps an even more important factor to consider on your fertility journey. Poor egg quality is emerging as the single most important cause of age-related infertility, recurrent miscarriage, and failed IVF cycles. It is also a major contributor to infertility in PCOS. Unfortunately, there’s far more mystery and misunderstanding about quality than quantity. The tests for ovarian reserve (CCCT, AMH, and so forth) are better indicators of quantity, but may be unreliable indicators of quality. Instead, what the medical literature will tell you is that the chief indicator of egg quality isn’t determined by what’s in a woman ovaries as it is by the date printed on her driver’s license.

“First and foremost, egg quality is determined by a woman’s chronological age,” writes one popular fertility website. That view is echoed in doctors’ offices across the country and in many other parts of the world. It is nearly universally accepted that ovarian reserve declines with age, though there’s notable disagreement as to when that decline starts to impact a woman’s fertility in a significant way. Casual Googling will lead you to websites claiming the decline begins at 25, while others say at 30, others at 35, and still other only after 40.

What does all this disagreement tell us? While it’s certainly true that maternal age has an impact on egg quality, there’s still uncertainty about exactly how aging impacts egg quality.

Percentage Game

Remember that we noted that the average girl has about 400,000 follicles at the onset of puberty? Let’s assume that 10% of these, or 40,000, are of poor quality. During ovulation, these poor quality eggs will not be chosen for ovulation. Even if the number of poor quality eggs does not increase, the percentage of remaining eggs that are of poor quality will steadily increase as the number of healthy ones are used with each menstrual cycle. If 10% of remaining eggs were poor quality at 15, some estimates suggest that 85% may be of poor quality by the time a woman turns 40.

Battery Effect

Another way in which age may impact egg quality is through what’s called the battery effect. Just as batteries in your various devices wear out over time, so too may the “batteries” that power an egg. In the reproductive process, there’s about a week between the time an egg is fertilized and the time it implants in the uterus. During that week, the mitochondria in the egg act as batteries to power the fertilized egg through the process of cellular division or meiosis. Researchers have noted that while the eggs of older women may appear of good quality and have little trouble getting fertilized, they often stop dividing at some point between fertilization and implantation. The mitochondria in older eggs may lose the “battery power” to complete this stage of the process.

Much of this information may come across as deeply discouraging to those who are contemplating having a baby. That discouragement is made worse by the way that most of the discussion about egg quality and maternal age is framed. You can’t roll back time, you’re told, and so there’s nothing that can be done about age-related declines in egg quality. As an expert fertility coach can tell you, this is unfortunate and incomplete information. You can improve egg quality.


This article is by Your Fertility Guide, which has been helping families conceive since 2014.


This article is written by Lin Weinberg, Fertility Coach at Spoken Origins and Your Fertility Guide, who specializes in helping clients conceive using an entirely new and truly personal approach to conception.