A reader writes:

In your post on Sarah Palin and amniocentesis, you wonder why she would risk having the results confirmed by amnio when she already had a diagnosis. The nuchal translucency test, where they measure neck thickness via ultrasound, is only a screening test. One cannot conclusively diagnose Down syndrome via ultrasound. So if one wants a diagnosis, one would follow up a suggestive ultrasound with an amnio or CVS (chorionic villius smpling).

The nuchal translucency test is given at 11-13 weeks. She said the diagnosis was confirmed a few days later. But amnios are given at 16 weeks - not a few days after the nuchal translucency test. Presumably she had a CVS, which can confirm the diagnosis, and can be done earlier than an amnio. However, it is much riskier to the fetus than an amnio (miscarriages occur in around 1 in 100 to 1 in 200 cases with CVS, versus around 1 in 1,600 with amniocentesis). Perhaps she did not want to admit that she had a CVS, since it is riskier.

Also, if she did wait until after an amnio to tell her husband, that means she must have been over 16 weeks pregnant. That's pretty far along in the pregnancy not to share with anyone.

She didn't tell her staff until she was seven months pregnant. The first reference to an amnio was in People magazine. Maybe it was shorthand for CVS.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.