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Tuesday, July 02, 2013

The birth of an terribly junky statistic on fertility and age

While exercising this morning, I was watching the CBS Morning News. The story was on the fertility of older women.

How long can you wait to have a baby?

The CDC says one in five women now wait until they're 35 or older to have their first child - a decision that often comes with anxiety about their biological clocks. Author Jean Twenge, of "The Impatient Woman's Guide to Getting Pregnant," and Dr. Joanne Stone of Mount Sinai Medical Center discuss the trend.

Twenge contended that the information about greatly decreased fertility among women over 35 (1 out of 3 not getting pregnant within a year) came from French data from the 1700s. If so, that’s clearly old data and time for an update.

But then she cites a study showing women over 35 have an 82% fertility rate (defined as getting pregnant within a year of trying), which isn’t that much lower than women in their late 20s (86%).

Sounds good, but then Stone noted that this 82% figure excludes women known to be infertile AND is among women who often had already had a child. (Twenge had omitted both of these pertinent facts, and didn’t seem that interested in acknowledging them when they were cited).

I credit CBS Morning News for making sure they had Stone there to clarify and for the interviewers making sure they asked the right question so Twenge’s numbers could be appropriately clarified.

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