Hello, Faith and welcome to Just Answer.
My name is XXXXX XXXXX it will be my pleasure to be of help to you today.
I'm so sorry to hear about your cat's attacks on your baby and that you and the baby ended up being scratched badly.
The first attack, when the baby was first brought into the house as an infant might have been caused by stress and territorial aggression, as the baby, new noises and the new scent may have cause the cat to view baby as an intruder. This second and more recent attack may have been the result of redirected aggression, especially if your cat had had a falling out with your other cat, she had seen something from the window, like another cat, bird, etc., outside, which she couldn't get to, or she may have been 'playing' stalk, hunt, pounce, as she would instinctively with your other cat.
I would suggest using a cat appeasing pheromone called Feliway which helps to calm stressed cats. The plug-in diffuser might be best for your needs. Here is more information: Feliway
There are two other calming remedies which are given orally and are over the counter:
Rescue Remedy for Pets and Composure treats
Don't use both these remedies simultaneously--choose one or the other, and each can be used in conjunction with Feliway.
You can also try to enrich your cats' environment by getting a kitty condo or cat tree, if you don't already have one, and get them some new toys. If they are kept busy, perhaps they won't be as interested in the baby. Below is a list of great toys, including a dvd for your kitties.
When you get the new toys, divide them into several groups. Change out the groups every few days, and they will feel like they're getting 'new' toys, which will intrigue them.
She will also enjoy a foraging toy, which fulfills her natural instincts of stalking and hunting prey.
Interactive toys you can play with her are laser pointers and feather dancers or fishing pole toys. There are even 'automatic' laser toys which you can set on a timer. Another thing she will like is a dvd with 'critters' of different types playing and doing other activities.
These are some examples of what's available; you can find many of these types of toys, etc. at your pet supplies store or order online--whichever is easiest for you.
To get the cat more used to the baby, you can take an old piece of clothing or blanket the baby has outgrown and use it to pet the cat; do this frequently throughout the day, so the cat will carry the baby's scent on her fur, all the time. This might help her not view the baby as a threat or 'intruder'.
It might be advisable to first have your kitty seen by the vet for a complete physical so you can rule out any underlying medical problems causing her aggressive behavior. If none of the over the counter calming remedies help, you can discuss a prescription anti-anxiety medication for her for a short term and see if that helps.
Of course, for the time being, don't ever leave the baby alone with the cat.
I hope things improve soon, and there will be no more attacks.