You laugh, but breast pumps aren't for pregnant women... They're for breastfeeding women.
And breastfeeding women still like to occasionally drink, which is why you have products like this on the market...
So it makes perfect sense. Mommy has a few drinks... She uses the breathalyzer, only to find out that maybe she shouldn't booze up her baby. So she uses the breast pump to "pump and dump" (which sounds way dirtier than it is) and makes the baby a bottle of formula instead.
C'mon, folks. WON'T SOMEBODY THINK OF THE CHILDREN??