If you grew up in the South, then you likely went to the Krispy Kreme Donut Factory early on Saturday morning. This was when the “HOT DONUTS” fluorescent sign was flashing brightest. It signaled that the machinery was running to produce hot fresh glazed donuts that tasted like heaven. The best part of the trip was the donuts, of course, but it also allowed me to understand how a conveyer belt works in a production line, as I stood with my 8-year-old face smushed against the glass watching the dough squeeze out of the vat and then roll along the belt getting glazed and then being hand-picked for the customer.
I often use this analogy when explaining ovarian function to patients. The ovary works much like a conveyer belt in that eggs are being produced and growing to maturity along a time continuum. A woman is born with all the eggs she will ever produce (the “vat of dough”). Some women are given a smaller allotment. This may be a quality that she inherited from her family, or this may be a sporadic event, meaning it randomly affected her. Certain medical conditions can also cause a rapid attrition of the eggs- chromosomal problems and Fragile X carrier status are the two most common, and a woman might not even know she has this condition. Lifestyle habits can also deplete the ovarian egg supply. Smoking is the most common cause and may cut off five years of a woman’s reproduction potential. Chemotherapy, surgery on the ovary, and endometriosis can also “eat away” at the amount of eggs in the ovary.
However, nothing can stop the conveyer belt that carries the eggs to maturation. I often get asked if birth control pills can “save” a woman’s eggs. They cannot. The eggs are coming down the conveyer belt at the same rate no matter whether a woman is on birth control, pregnant, nursing, or even taking fertility drugs. There are approximately 1,000 eggs that “come of age” each month. The brain sends hormones down to the ovary to grow one of those to maturity and allow it to ovulate. The other 999 eggs “fall off the end of the conveyer belt.” We use the medical term atresia to explain that they dissolve even if not used that month. If you are on birth control, pregnant or nursing, you will still have 1,000 eggs that undergo atresia in a given month. That is why some older women might get pregnant, but then find out they are in menopause after delivery, or might be ovulating fine before they started birth control, but by the time they stop birth control they may discover they are in menopause.
I also get asked if fertility drugs, and the multiple eggs they mature, will make a woman go into menopause earlier than they otherwise would have. Does it use up their supply of eggs? The answer is no. Again, nothing can change the speed of the conveyer belt. Just because we give a woman extra hormones to mature more of the eggs that come of age that month, it does not allow us to go upstream and grab extra eggs from the future. To use the donut conveyer belt analogy – you can pull more donuts off the end of the machine to eat before they fall into the trash can, but you cannot grab donuts that are too high up on the conveyer belt and eat them early.
Now I realize that this analogy may not make sense to all of you reading this- some of you are not familiar with Krispy Kreme donuts. So first, I encourage you to take a trip to Nashville, TN and see the donut machinery. But if that is not in the cards for this summer, rest assured that you are not using up all your eggs by doing fertility treatment. Also remember that nothing can stop the donuts from falling off the end of the belt if no one is there to use them. Don’t let those eggs go to waste!