Yes, she left the door unlocked, whether accidentally or deliberately. If you leave a door unlocked, youare making it more accessible to intruders.
If you want to make it more than that, you need to say the woman has more knowledge of some offspring that does not yet exist than of vargrants that actually exist, but she does not know personally.
I don't quite follow the last sentence. However, leaving the door unlocked is still a horrible analogy. The fetus is there AS A DIRECT RESULT OF THE MOTHER'S ACTIONS. I don't know how you can argue that, or why you are even trying.
The fetus did not decide to be conceived. The mother decided to conceive the fetus... or at least engage in risky enough behavior that conception was an entirely foreseeable outcome.