I think you meant to get women's opinions on this, and you will, here in the Women's Forum. If you had wanted men's opinions, I'm sure you would have posted somewhere else....
For starters, I'm assuming here that she isn't a serious shooter at this time and doesn't own her own gun.
First, she should go to a handgun safety class. She's going to have to pass a safety test anyway in order to purchase, and she'll learn a lot. And she's going to have to go to a Carry class later. I imagine you know that you can't purchase a handgun for her in your name.
Next thing is for her to try out on the range, every gun you own, carry size or not, to determine a model and caliber she likes. (It would be better if you didn't go with her to micromanage. No offense meant, but men do it unintentionally.)
Then she goes to the gun shop alone, without you, and handles more guns until she finds one she likes. And does not buy it on the spot. Off she goes to the range to rent her top three picks, if you don't already own them. THEN she can make an intelligent decision.
I know this sounds like a lot of process, but we've all been through it time and again. If she doesn't like the gun, she won't practice. If she doesn't practice, she won't be able to defend herself. And if she isn't totally up on safety, she's a danger to herself and your child.
So put off gun selection, until you get the basics in hand. She also needs to get totally clear on whether she is allowed to carry on school grounds, even if she is a teacher and even if she has a CCW. (I'm not sure on this, but she should be).
What she can shoot through is the least of your problems. If she's juggling a baby, a handbag and a diaper bag, how will she ever draw-aim-fire? Better to learn to shoot well first and figure out carry options second.
WHAT I HAVE LEARNED SO FAR, MOSTLY THE HARD WAY
• Do only safe sex. Never have sex with someone crazier than you are.
• Don't marry or move in together before you're both at least 25.
• Don't have children until you're married five years or at least age 30.
• Put 10% of your salary into savings every month no matter how broke you are.
• Don't ever screw around with the IRS.
• Keep a handgun on your bedside table.
• Don't smart-mouth judges, or cops who stop you on the road.