This is a valid question and something that units rarely deal with so there is usually a bit of an education process involved in the matter. There are several regulations and manuals that deal with pregnancy and the issues involved with it. These regulations include: AR 350-1, AR 600-9, FM 7-22, and TG 255A-E.
Since the Soldier is in the National Guard, the Soldier should take their civilian medical documentation to a military doctor and have them verify the medical condition and then the military doctor should fill out a military profile (DA Form 3349). This should be all that is required to ensure your spouse receives the required recovery time.