Mom will say whatever mom would want to (knowing that you could also tell mom not to interfere too much given that it is mainly an issue for you), but even then that would not not take away your privilege as a customer.
I agree with @Bethany Heinrich-- I would definitely make completely sure that she is in fact pregnant before doing anything. If she wants him, here's the script for a respectful conversation with him that spells it all out without drama:
Her: "I have something I want to tell you about our relationship that might be sensitive. When is a good time to talk about it?"
Him: "uhhhh go ahead." (or whatever he says, hopefully he says yes to the convo. If he doesn't actually say yes to the convo, then don't have the convo and make your decision on your own)
Her: "I recently found out that I'm pregnant with our child. I'm interested in raising it together but I want to know if you're interested in having a committed relationship if we go that route. Otherwise I will (put it up for adoption or abort it-- whatever she plans on doing). What do you think?"