you might want to see what kind of cobra provisions your current policy offers-it may end up costing less than private insurance.
also remember that while a ppo offers choices in doctors you usualy have a deductable to be met as well as a share of cost on every test, appointment, procedure. 10 percent may not seem like a lot but when you start adding up all of the pre-natal appointments, routine bloodwork, sonogram, let alone one extra night in a hospital (i had a no problem delivery but because i was running a temp. for several hours following delivery they decided to keep me and the baby another 24 hours) you could be looking at several thousands in out of pocket expenses.
if you have a particular ob-gyn in mind check and see what coverage they accept (and actualy the insurance billing people in their offices are pretty good at telling you which policies offer the best coverage), but also check with your desired pediatrician to see what coverage they accept (if you end up with an hmo type of policy they often won't let your child see a doctor outside the mom's medical group).