You’ve probably heard the phrase “The clock is ticking…” so often that it’s nauseating – or at best ultra-cliché. But for women who have bearing children on their radar, the ‘ticking’ feeling can’t be just brushed off as a nothing.
What Happens to Your Eggs as You Get Older?
You’ve probably heard the phrase “The clock is ticking…” so often that it’s nauseating – or at best ultra-cliché. But for women who have bearing children on their radar, the ‘ticking’ feeling can’t be just brushed off as a nothing. The complexities of fitting in career advancement, the search for an ideal partner and other life complications all before having a child means that that “ticking clock” isn’t just an annoying joke; it’s a legitimate concern. While fertility doesn’t suddenly disappear in a poof of smoke, neither does it last forever – and the process of fertility decline starts in one’s 30s. Here’s why – and here’s what you can (and can’t) do about it.
A woman’s supply of fertile eggs is not constant over her lifetime. While an adolescent girl has approximately 400,000 eggs available, these numbers taper quickly. Dr. Sherman Schreiber, author of “Beating Your Biological Clock,” explains that once a teen starts her menstrual cycle, she loses 1,000 immature eggs every month, and that this loss is simply a biological process, not something that can be changed by factors over which we have control. The average woman has around 25,000 eggs available at age 37 and only 1,000 at age 51. One might still think – hey! In order to conceive a child, only ONE healthy egg is necessary. So those numbers still sound pretty high. But successful conception is not only a numbers game.
Not all eggs are created equal. In order for an egg cell to be ready to be fertilized, it must undergo several cell divisions first. In the complex, amazing process that is cell division, the chromosomes must replicate themselves, then be split perfectly as the cell divides into two. As egg cells get older, they have more difficulty with the division process. One issue can occur with the chromosomes themselves. They separate too early in the process of cell division, giving the resulting egg the wrong number of chromosomes – called aneuploidy. Another issue can occur with the parts of the cell that surround the chromosomes and make them line up correctly during cell division. In aging egg cells, these parts – called the microtubules – often have less control over the process, and end up – again – giving the resulting egg the wrong number of chromosomes.
What happens to an egg cell with the wrong number of chromosomes? It may either:
- be incapable of being fertilized
- be incapable of healthy growth and development (leading to early miscarriage)
- develop into a baby with Down syndrome (this is caused by a very specific problem in chromosome division)
Bottom line? While plenty of older women do bear healthy children naturally, the older an egg cell gets, its chances of abnormal development increase, and its chances of resulting in a healthy birth decrease.
Present and Future Solutions
Professor Greg Fitzharris suggests that in the future, we might be able to take the chromosomes from an older woman’s cell and put them into the cell of a younger woman. That way, the genetic material would remain entirely yours (NOT like getting a “donor egg cell” today), but the younger cell microtubules would make the chromosome division more successful. Exciting as that sounds, it’s still far off. But women who are thinking in advance about fertility can effectively preserve their egg cells’ youth – even today. Women who freeze some of their eggs when they’re in their early 30s, for example, can use them in their 40s when they decide it’s the right time for parenthood. This freezing process is called mature oocyte cryopreservation and it is done in fertility clinics around the world. Freezing eggs effectively stops the clock, retaining the quality in both the chromosomes and the surrounding cell matter. It’s one of the best solutions we have today for preserving fertility. While there are never any guarantees, being aware of the options, anticipating and planning ahead are the best steps you can take to make your motherhood dreams can come true.