@astrisize - Hmmmm. That's a tough one. So, in theory, it should be possible... assuming you have an uncomplicated pregnancy and delivery, and are willing to take very little maternity leave (as in, 2-3 weeks - maybe as much as 4.5 weeks if you use all vacation and sick leave all at once - and then, of course, never get sick again for the rest of the year). The question is how much you're willing to accept (1) the risk that the pregnancy does not go as planned, and (2) having your baby with that little flexibility.
It's also possible that if this all happens once you're already matched into both programs, then they'll be ok with you eg finishing your transitional year a few weeks or a month late and starting the next program an equivalent amount late. But.... it's a gamble.
That's a tough one!!