Oh, bless your heart. As a mom of 4, I well remember the jumble of nerves involved in that part of your life.... adding something like this to it would have been enough to send me off the deep end.
I am just curious how they even KNOW that you want to rent the place out? Certainly, I am not advocating violating any loan terms. But, most people don't call their lender to ask permission, I honestly don't know what they normally say. I've seen people be told that if they are moving from house A and applying for a loan for house B, with the intent to rent house A, they will need to refi house A into an investment property before they will be able to get a "primary home loan" on house B. But, it doesn't sound like that is your situation.
If you do violate loan terms by renting the property, their recourse is likely limited to "calling the note" meaning making it due and payable immediately - but if they know that you won't be able to pay it, I do not believe they would "rock the boat" and force a property into foreclosure - they've got enough of that on their hands. Besides, I would say pregnancy is a change in your life that makes you reevaluate your living situation, and may force you to make changes in where you live. Why would you allow the place to sit empty when you could rent it?
By the way have you looked at options refinancing under HASP - see the link below. You might qualify for a refi which could reduce your monthly payment and help you out.