Of course, making this change will come with its own set of challenges. I will probably have to beef up the plot (which will also help make the book longer, since it's only around 50,000 words long, which would suffice for MG, but would probably be better upward around 70,000 for YA). I will also have to add more/deepen the emotional content. I will also have to tinker with the prose to make it more suitable for YA, which is something that will probably be particularly difficult for me. I read YA all the time, but writing one—that’s a whole other story. I'm more versed in MG now, since my thesis for my MFA program had been an MG novel, but I think YA will prove to be a bit difficult.
My other option is to stick to MG, but soften the procreation aspect. I think it's possible, but I'd have to think on that one for a bit, so we'll see. At the moment I'm leaning toward shifting the story to YA, but I'm definitely going to have to give this whole thing some serious thought. Wish me luck!