Tuesday, February 02, 2010

Ohmygod! My Eggs, My Eggs!

This is another bit of the kind of popularization we wimminz are exposed to:

A new study from the Universities of St. Andrews and of Edinburgh is offering a more accurate understanding of fertility and its decline with age, which researchers say is steeper than previously thought.

The study, which involved about 325 women of different ages from the United States and Europe, investigated the number of eggs that remain in the ovaries over time. This number, said the researchers, peaks at about 20 weeks after conception and subsequently drops until no eggs are left at menopause.

At the age of 30 years, only 12% of the maximum ovarian reserve - the number of eggs with which women are born - is typically present; by 40, only 3% remains.

The average egg quality also decreases with age, which increases the difficulty of conception and the chances of an unhealthy baby.

"Women lose eggs a lot faster than we thought," said Good Morning America medical contributor Dr. Marie Savard.

She pointed out that women need to hear that the biological clock runs fairly quickly, and that the chances of having children are jeopardized the longer one waits.

Note that the link is to a forced-birth site.

Let's apply some logic to that story. If the number of eggs peaks 20 weeks after conception, shouldn't that be when women get cracking on getting pregnant, based on the logic of this story? And how many eggs is 12% of, say, 300,000? Probably enough to get pregnant from, given that only one ovulating egg is actually needed. Even 3% of 300,000 would do it, you know. How many eggs remain when a woman is twenty, by the way? If women somehow "misplace" 90% of their eggs before the age 30, how many do they misplace before the age 20? Age 10? These things matter for proper understanding of the study, you know.

I think the "maximal reserve" concept is meaningless, because women never use any but a small fraction of all the eggs they are born with. Now, the question of egg quality may be more meaningful, but this study doesn't address that.

The conclusion the U.K. Telegraph draws from all this is the expected one:

The research is the latest to warn women that they must not leave it too late to conceive.

Women's fertility declines substantially after her mid-thirties but the speed of the drop differs for each individual and many face heartache when they find they have left it too late.

Some doctors have called for regular fertility screening in the same way women are screened for cervical cancer.

There ya go!

Just to put things into perspective, I dug around a little to find information on age and sperm quality. Those studies do exist:

With each passing year, semen quality in adult men declines, suggesting that age plays a greater role in male fertility rates than previously thought, according to a new study by researchers at the University of California, Berkeley, and Lawrence Livermore National Laboratory.


The new report looked at 97 men aged 22 to 80 and found increased fragmentation of the DNA in sperm as men age.

"This study shows that men who wait until they're older to have children are not only risking difficulties conceiving, they could also be increasing the risk of having children with genetic problems," said Wyrobek.

Yet somehow I don't hear the same urgency from the media about the age-related fertility decline in men. Or do they advocate fertility screening for men, too?