Pregnancy, like HIV, is a pre-existing condition under U.S medical insurance guidelines.
Well, that one is still true -- at least for now. In the year 2014, when a host of provisions of the U.S. Affordable Care Act will go into effect, so-called "pre-existing conditions" like HIV and being pregnant will no longer be grounds to deny or overcharge for heath coverage. There are already several preventive services covered under the Affordable Care Act that pregnant women can take advantage of right now.
Read more about benefits available to pregnant women living with HIV.