It could be as you outline here. [However, she didn't have to put her child in foster care. That was only bandied about because "mom" fell through, and she had not thought about a "Plan B". She could have found someone else to take care of her baby (i.e. the baby's father...baby's father's mom, aunt, sister, etc.). As dysfunctional as my family is, I can think of at least 5 people I'd place my child with, if I absolutely had to (meaning, them, or foster care.), not to mention, 2 or 3 friends.]
Again, it could have happend as you stated above (she couldn't ignore her maternal promptings) ....or....it could be that here was a young woman who thought she was getting one over on the military, or, at the very least, having her cake and eating it too (I get to stay in the military, draw all the benefits, and stay safe and warm at home), while the rest of her unit deploys.