I will be having a baby soon, and I wear the Hijab. Do I have to wear my Hijab during labor if a male doctor or a male nurse is present and there is no option for a female doctor or nurse? Or am I not obligated to keep it on when in labor?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

If there is no female doctor or nurse, there is no harm if a male doctor is present to supervise your childbirth. He is allowed to see only what is necessary of your body unveiled, i.e. you have to wear your full Hijab, but allowed to unveil what is needed for confinement.
As a rule, a Muslim woman is required, to visit a Muslim female doctor for treatment. If one is not available, she can go to a non-Muslim female doctor; if not available, she should give priority to a Muslim doctor.
Allah knows best.