While trying to conceive my first 40s baby, one of the first issues I became aware of was early or premature recruitment of follicles. I didn’t come by this information by way of my doctors, oh no… no, no. Not one of my Reproductive Endocrinologists said “maybe you have early recruitment of follicles and here is what the current research says”.
Early recruitment causes a cascade of events to happen earlier than they should. When estrogen levels drop quickly too soon, it allows a premature rise in FSH. What does FSH do? It grows your follicles. So then you are stuck having a shorter follicular phase with hormone levels higher than they should be, and ovulation happening earlier than ideal because folliculogenesis is happening days ahead of its normal, typically younger, schedule.
There are four major events involved in folliculogenesis: recruitment, primordial follicle development, selection, and atresia. There are two types of follicles we will be discussing: primordial (preantral) follicles and graafian (antral) follicles.
When we are born, we have a ton of primordial follicles. We are talking 1 – 2 million of them! Despite losing over 95% of them by the time we are 40, we do still have some at our age! Primordial follicles are teenie tiny, that’s how so many can fit inside each over, which is only the size of a grape. Primordial follicles are dormant until they are recruited to complete their destiny.
Most of you are probably used to the term antral follicles, but they are scientifically called graafian. I will refer to them as antral. If you’ve ever been to an RE, you have probably gotten an antral follicle count (AFC).
Recruitment and Primordial Follicular Development
Recruitment is the process by which dormant primordial follicles are woken up by certain hormones and “recruited” to continue developing and growing. Primordial follicular development is the developing process.
Dominant Follicle Selection and Atresia
The last two events are selection and atresia. In each menstrual cycle, typically one antral follicle will continue dividing at a quick pace while cell growth comes to a stop in the others. Once the dominant follicle is large enough, it produces its own estrogen which inhibits FSH, thus killing off all other follicles, or atresia.
Why Aren’t More Doctors Talking About Early Recruitment?
Many REs still believe the cycle disturbances seen in women TTC with advanced maternal age are due to events that happen during the follicular phase of the current menstrual cycle. This is proving to be a very ignorant way to think. The menstrual cycle is divided into phases, yes, but there is overlap between each cycle, and things do not just reset and then begin anew on cycle day one.
The life of your menstrual cycle is a continues flow of predictable patterns in hormones levels. Carefully timed and routine blood tests and ultrasounds done in the luteal phase of female patients have proven that the disturbances in older women’s cycles are due to recruitment happening earlier , i.e. “prematurely”, and during the luteal phase of the previous menstrual cycle (Zonneveld, 2003).
“It is concluded that in spite of a dramatically decreased number of recruitable antral follicles, follicle development, hormonal events and endometrial growth are remarkably undisturbed in older women. Apparently, a grossly decreased number of antral follicles does not result in cycle disturbances until after the age of 45±46 years” (Z.van, download above).
Can You Stop Early Recruitment?
There is protocol that can greatly reduce the negative effects of early recruitment. Find out what you can do to alleviate some of these effects in my e-book, available for pre-order today!
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Erickson, Gregory F. “Follicle Growth and Development.” The Global Library of Women’s Medicine, 2009, 10.3843/glowm.10289. Accessed 24 Sept. 2020.
Zonneveld, P.v. “Do Cycle Disturbances Explain the Age-Related Decline of Female Fertility? Cycle Characteristics of Women Aged over 40 Years Compared with a Reference Population of Young Women.” Human Reproduction, vol. 18, no. 3, 1 Mar. 2003, pp. 495–501, 10.1093/humrep/deg138. Accessed 4 June 2019.
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