[JayGalt]

The only problem with this chart is the context. This is # of births /1000 women. What was the status of these women? Were they all trying to get pregnant? The drop off in this chart is much more steep than in most of the studies I have seen.

[Mrs. Don-o]

Good catch. Your observation is exactly right, which shows the limits of proving things with charts.

If you define fertility as plain biological "ability to natural conceive, carry and bear a baby, barring deliberate surgical enhancement or impairment" you'll have one set of numbers; if you define it sociologically as "number of women actually giving birth per thousand," you'll get a different set of numbers.

As I understand it, well more than half of American women ages 35-44 have been sterilized; another 15% in that age group rely on the sterilization of their partners.

That should not be treated statistically as if it were natural infertility.