Have you considered immigration issues? I'll make an assumption that your wife is NOT a US citizen or permanent resident alien (if she is either of those, then disregard this post). At 30 weeks, I would guess that she'll be obviously pregnant even to a casual observer. This being the case, an obviously pregnant woman arriving in the US may get some grief from DHS if the officer believes that she's coming to the US to give birth, even if she otherwise has a valid visa and is otherwise eligible for admission.