advanced maternal age

Tuesday, February 7th I attended a lecture at the Marian Miner Cook Athenaeum at
Claremont McKenna College.  The speaker was R. Scott Hawley, who is an American Cancer Society Research Professor at the Stowers Institute for Medical Research in Kansas City, MO.  His talk was entitled "When Good Eggs Go Bad--Because Sometimes Even Chromosomes Aren’t Perfect."

retinoic acid

He talked about the process of meiosis, which takes place in humans when the female egg cell meets a male sperm cell. 23 chromosomes from each cell have to meet and pair up in order to start the process of cell division, yielding a single hybrid offspring containing 46 chromosomes. Mistakes can be made in the process of preparing genetic material (DNA) to participate in this complex dance of macromolecules, which can result in too many or too few copies of a chromosome to be present in the offspring. When 3 copies (instead of 2) of chromosome 21 are present, characteristics of Down syndrome are observed.

Because females make all their eggs while they are themselves yet unborn, the eggs can become exposed to a range of environmental factors over the course of a woman's life, putting them at risk for DNA damage and defects to their eggs.  Males by contrast can make billions of sperm at a time, on a daily basis (and they don't start doing it until puberty) by a process regulated by retinoic acid.  Prof. Hawley showed this frightening graph (which I recapitulated using data from this source) relating risk of chromosomal abnormality and maternal age, and I started watching the clock tick-tock.  My biological clock.

There are countless studies showing that modern women are delaying child-rearing in favor of their careers.  And there are women like Sarah Palin whose son Trig has Down syndrome.  Rick Santorum has a daughter with too many copies of chromosome 18.  The conversation over lunch this past week turned to the church's pressure for couples to reproduce (and political opposition to funding contraceptives for women of child-bearing age).  It's all too real and scary for my brain right now.

(c) Pavel Popov 

Environmental and lifestyle factors affecting a woman's probability of experiencing fertility problems include: age, smoking, excess alcohol abuse, stress, poor diet, athletic training, being overweight, and sexually transmitted infections.  As I consider the possibility of getting pregnant, I am also wary because of the amount of risk factors present in my own life (being a chemist and living in a pretty high-stress, pollution-rich area).  I try to strike a balance between over and under weight, under and over exercise, good and poor diet, I guess moderation is the key.  Given the nature of information these days, one could probably justify anything.

What I don't like is that it somehow sounds like Eve is being blamed for everything again.