"computing" was a secretaries job. It was a position typically filled by a woman who worked with numerical data (working with spreadsheets, calculating an insurance premium, etc...mission critical back end stuff). During WW2 pretty much all these jobs were filled by women.
Computing and IT started to come of age during the post WW2 boom so there would have been a lot of women with the math background to make programming and working with computers somewhat of a logical next step in ones career.
Coincidentally, these woman who had math backgrounds were also some of the fist to have their jobs automated out of existence (the woman who calculates someone's insurance premium is replaced with a box of punch cards).
Just speculating but it wouldn't be a stretch to see how when choosing between going home or switching careers the woman who didn't become the stereotypical 50s-60s housewives as their jobs were automated found new jobs writing punch cards (programming) and operating computers.
(i'm in a hurry, probably lots of grammar mistakes in that)