Here's my big problem with it, from a biological standpoint - we have no evidence that pregnant women aren't the ONLY ones who can carry these 'bursters. And even if the homeless lady wasn't pregnant, it still implies they need a female womb to gestate these bursters.
Which would further mean that, at some point, the alien evolved an aspect of its reproductive cycle that REQUIRES a mammal's reproductive system to make use of it. Even though the alien is about as far from mammalian as you can get.
....
....
That's utterly asinine.
If we had scenes of the PredAlien doing this procedure on men as well as women, it wouldn't be so bad, but... shit.