Welcome to the forum, Alison and Zee! I understand your concern, it's a very common one either before or after the baby is born because parrots that bond deeply to their humans do get jealous of their displaying affection for other beings (and I say beings because, as far as they are concerned, other birds, spouses, dogs, cats, etc. are all competition). My female Senegal, Zoey, used to bite my husband when she first came to me (all my birds came to me as adults, I don't buy babies) and she would not allow any other bird to perch on my person. But, as time went by, she stopped biting him (he never even tried to interact with her, she would fly to his shoulder just to bite him
)and became more independent in that she started flying around and perching on other places besides my shoulder (she would not move from it for a couple of years after she came) so other birds took her place when she wasn't there. But she never, ever, ever bit my grandkids. She bit my grown children but only if they tried to interact with her but never the grandkids. Of course, I never allow children to interact with my birds but that wouldn't have stopped her if she had wanted to bite them (it never did with any adult
Yours is at a bad age because, in the wild, she would have started her family right about this age. So I would suggest your keeping her to a super strict solar schedule with, at the very least, 1.5 hours of twilight both in the am and the pm, and reducing her protein intake during the cold weather months to avoid her becoming overly hormonal and making sure she is not out of her cage when you have the baby with you - just in case, you know? I don't think she will go out of her way to bite him/her but better safe than sorry, right? Aside from that, I would recommend you try your very best to keep her routine exactly as it is so as not to make her resent him/her (they are smart and she will put 2+2 together if everything changes after the baby's arrival).