"America's Leading Experts in Reproductive Health"
Fertility Can Decline Rapidly
in Women Over 35.
     
 
   

 
   
 
   
   
   
 
 
   
   
   
 
   
 
   
 
   
 
   
   
 

Review Fact Sheets from the American Society for
Reproductive Medicine.

 


Age and Fertility

Ovarian function is typically directly linked to a woman's age. A female has the greatest number of eggs that she will ever have when she is in her mother's womb at midgestation, or 20 weeks. She has approximately 7 million eggs at that time, and the number of eggs declines throughout her life.

At birth, the number of eggs is decreased to about 2 million. By the time of her first menstrual cycle, a woman has only had about 300,000 eggs left. The rate of loss (or death of her eggs) is a function of her age. A woman is always loosing eggs, even when she is pregnant. The only thing that changes is 'how fast' the eggs die off.

When a woman is about 28- 29 years old she starts to loose eggs a little faster, and by the time she is 35 the rate of loss of eggs is much increased. By the time a woman is 40 years old, the rate of dying eggs is extremely rapid. A woman will ovulate approximately 450 eggs in her reproductive lifetime, less than 1% of her initial count. By the age of 35-40 the quality of her eggs are decreasing, such that by age 40 the chance of conceiving (with her own eggs) is no more than 10- 15 %. As a woman gets older her chances of pregnancy and subsequent delivery is extremely low, with an increased risk of chromosomal abnormality. Thus, after 35 years of age, a woman has an increased risk of having a child with Down's syndrome (and other chromosomal abnormalities).

There is no direct way to determine a woman's egg quality. However, we have indirect ways to access egg quality. One way is to simply measure hormones, FSH, LH and estradiol on the third day of the menstrual cycle. If the FSH is elevated (regardless of the woman's age) she may have less than 5% chance of getting pregnant with her own eggs.

We can also measure and count the number of egg pockets, named follicles that she has on the third day of her menstrual cycle. Eggs are microscopic and cannot be seen by the naked egg. However, we can see and measure the egg pockets on transvaginal sonogram. It is generally accepted that greater than 14 egg pockets (follicles) are reassuring of fertility. Less than 5-7 follicles ( antral follicle count, or AFC) is significant for decreased ovarian function or reserve.

Another test is the Clomid challenge test (CCT). With the CCT blood is taken on the third day of the menstrual cycle (checking for the hormones FSH, LH and estradiol). The woman then takes two Clomid pills (100mg) on cycle days 5 through 9 and she returns on the following day (cycle day 10) for repeat labs (FSH, and estradiol). This test is usually recommended for any woman 35 years old or greater. If either set of labs (day 3 or day 10) is abnormal, this woman may have less than a 5% chance of getting pregnant with her own eggs. A woman that is menopausal typically have an FSH level of 25 or greater. For example, a woman who is 40 years and has an FSH of 68, and an AFC of 4, probably has less than 1% chance of getting pregnant with her own eggs.

FSH- (follicular stimulating hormone) is a hormone that stimulates the eggs to mature and grow within the ovaries, (along with LH) is produced by the pituitary gland in the brain. These hormones send messages to the ovary, and in response the ovary makes estrogens (primarily estradiol). The estrogen 'message' is sent back to the brain and as long as the ovary is competent and makes the estradiol the brain is happy and continues to send 'normal' amounts of FSH signal back to the ovary.

However, if the ovary has decreased ovarian reserve (less competent), the FSH will be elevated. Imagine being in the kitchen of your home and you're calling out to your husband who is in the living room (watching TV) and he doesn't hear you. What are you going to do? Well, you're going to call him again, and again and perhaps louder each time (maybe even yelling his name eventually). Well, this is what happens to the communication between your brain and ovaries.

If the ovary is not responding (not making enough estradiol) it fails to communicate with the brain (as your husband not responding to your calling his name). This will invariably cause the brain to send more and more messages (perhaps yelling at the ovary, as you may have done to your husband). Thus, the lower the ovarian function the higher the FSH level will be in the blood. So a high FSH level is not good. This is thus an indirect indication of poor ovarian reserve or ovarian compromise.

Since eggs cannot be resurrected, if a woman has a significantly elevated FSH level, her best option for pregnancy may be donor eggs. Women over 35 should especially seek an infertility specialist early (after 6 months of unprotected intercourse without conception). Of course women 40 years and above should seek an infertility specialist immediately.

( Read an Article on Delayed Childbearing Trends by Gordan Kuttner, MD)



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