This seems like some odd form of recycling. It's tunes like "Let's Get It On" by Marvin Gaye that help conceive the little ones in the first place. Apparently this particular tune, at least for the toddler above, can stop them from crying, and have quite the calming effect on them when it's played for them outside the womb. 

I would stop here though. I'm not sure what adverse effects might come as a result of playing "Sexual Healing" for her... and that's just creepy anyway.