Ha Im sure your baby will love your voice no matter how 'bad' you think it is!
My DH is the worst singer out, and I seriously cringe when he sings to our kids and I have to hold myself back from rushing in and saying "oh my gosh you are singing that SO wrong, and totally out of key, just STOP, please, you're traumatising my ears!", because the kids love his singing and beg for more songs!
I remember my Mum singing to me and she was tone deaf, I used to love the songs tho. Until I got to the age where I realized how bad she was, and then at church I used to be all embarrassed at her singing and would glare at her and say "shhhhh Mum, too loud" ! LOL poor Mum!