Hi, my ex girlfriend is pregnant with my baby and the doctors appointment to find out the sex of the baby is next week and she told me she didn't want me there. Do I have any legal right to be there? Because that's a doctors appointment I really don't want to miss.

Uhhh Yea

You're the father Of that Baby... right?
It takes two to make a baby& there's got to be a reason why she doesn't want you there...

No, you as the father have little to no rights prior to the baby being born. She has full control of who can be at her doctor appointments and who can be at the hospital at the birth.

After the child is born you can file for joint custody or for visits.

Not your call. Great you are interested, but no you have NO legal rights to be at any of her doctors appointments.