premise: Baby loving his or her first time in the swing. hypothesis: A baby is swinging outdoors with his brother.
neutral: The word 'baby' is gender neutral, and it cannot be inferred that it's a boy or girl, therefore it is not known if 'his' or 'her' should be used; a baby swing can be hung in a door, it can be on a stand, or it could be outside, the fact that it's a swing does not indicate the location of the swing, whether it's indoors or outdoors.  There is no way of knowing if the child is an only child, or if it has siblings, the fact that the baby is in a swing does not mean that it is with his brother.