Am I responsible for unborn baby and its mothers medical bill?

You may want to review the statutes and other materials posted here.  Short version, there is a statute permitting a court to hold a father liable for the costs of "pregnancy and confinement," although in most cases where the parties have similar earnings most expenses tend to be split.  It might be a good idea for you to confer with a family law specialist about all matters relating to potential child custody, visitation, and support.  Much of the background can be reviewed on our web site.