Please don't worry that you will be torn between the labor room and the AOS interview, or that your beloved will give birth in the INS office or some other catastrophe! If I was you, I would send a registered letter explaining that your wife is imminently due to give birth and that you would like to postpone the interview until a month and half after the EDD to avoid any such problems. If you are really worried take an infopass appt. and ask what to do!