What’ are the Army regulations for pregnancy?

Go see your Primary care provider.

See your OB/GYN and ask him/her what restrictions you have. From my experience with my wife through three pregnancies, you can probably do a forced march to the rifle range if necessary, but each pregnancy is unique. Don't go at it as though you're trying to avoid your duties and don't expect to be "bedridden" for the rest of your pregnancy, just ask for a medical opinion and ensure the advice on your restrictions is officially provided to you and your command. Getting a copy for your NCOIC would be wise since "the word" doesn't always make it down from the top. Your restrictions may change as the pregnancy advances, no one wants to harm or endanger you or the baby, but you must keep everyone advised.

What specifically are you wanting to know?