Interesting that Woodbury also has a pregnant woman soon to give birth.
If we get to see the results of this baby and Lori's, maybe we'll find out if Rick has some special immunity passed on to Lori's baby while this unknown child doesn't. More likely, it's not going to be addressed.
^??? Are you assuming that all children will be born undead?
I don't know. If they're all infected and the child dies before/during/after birth, does the child become a zombie?
There's been positing that Rick had indeed died in the hospital as Shane had thought, but didn't become a zombie--similar to Hershel dying and being resuscitated and not becoming a zombie. If so, Rick may actually be immune, possibly along with Carl.