Stalker,
Xenomorph,
17 years ago
Any hostile threat that poses any reasonable danger to a predator is usually killed, regardless of what it is. A predator would generally not kill a pregnant female under any circumstances, as it would be taking away an unborn & defenceless life, which is considered dishonourable, however a woman with a gun is quite a different matter, & a predator would kill them without a moment's hesitation.
As far as a child with a gun, they would be voluntarily attacking the creature, so would more than likely not be considered defenceless. The predator was about to put a plasma bolt through the boy in the cemetary in Predator 2, until he determined that the child did not hold a real weapon.
Generally only males that are warriors or fighters in some way are targeted by a predator, anything from police officers to criminals, although anyone who tries to fight against a predator could potentially find themselves killed, depending on whether the predator felt they were a sufficient enough opponent to take down.