Human life trumps all other concerns. There is 3 definite lives in the Pregnant Women group, 5 in the Orphans. Whether a 5 month old is a person or not is unknown. Letting one die may be a full ended life, it may be inconsequential, I don't know. If I were to assume a 50% chance, then the utility of a lost 5 month old is worth half a life on average. This would amount to a utility of 4 and a half lives to the orphans 5. I'm not comfortable with assuming an even 50/50 chance when lives are at stake, since 50% is just a figure I assume when getting a precise figure isn't feasible, so I will look to other factors, to at least consider. Orphans are young, and have a good chunk of there lives ahead of them. The women are older, and have less of there lives ahead of them. Since all life is valuable, I need to consider the span of it. The possible babies have only slightly more of there lives left then the orphans, and since it is only a chance of longer life, and I am naturally risk adverse, that doesn't close the gap quite enough.
So overall, I think I would have to save the orphens. Realistically, the calculations are extremely close, and I'm not sure I could do the calculations that fast in the heat of the moment. I would probably choose arbitrarily.