"Cingular is the name of a large US cell phone company, yet I associate the word cingular with pregnancy for some reason. Can anyone suggest what the connection might be?"

Here's my suggestion, inspired by the link to the AWAD archives:

"enceinte: adj. Carrying an unborn child; pregnant." (American Heritage Dictionary, 4th ed.)

I've always known the meaning of this word, but have often wondered what pregnancy should have to do with being encircled or wearing a belt. AHD4 says is goes back to Latin "inciens" meaning pregnant. Which fact still leaves me wondering. Now I will use up even more work time chasing the IE root.