I balked, but the clerk said that they ask for due dates because they obviously don't want to keep extending offers & coupons to women after they're not even pregnant anymore. I was like okay, that's the first ever explaination I've heard that may justify asking for personal information on me. And I do like coupons. So I signed up, since hey, pregnancy is temporary, and presumably so will my existance in this system.
Turns out no. I'm still getting emails, eight months after the due date I gave them (which was fake early, just to spite them). I finally unsubscribed. We'll see how that goes.
I'm never trusting another store again. I already get really offended when stores ask for my phone number, I glare and say "I don't have one." I give the grocery store nothing but fake info in exchange for those discount cards.
But motherhood and destination maternity in general: you suck.