So my brain goes... maybe you should play DubStep to develop a sense of rhythm. It can't hurt any kids we'd have - neither of us can keep rhythm well!
It's not DubStep, but this is the song I played to Penny a few times. It's sure not Mozart.
BTW, I'm pretty sure a fetus can hear vibrations of the low bass more easily than other musical sounds, so I don't think I'm all the way crazy on this. Thoughts?