General Advice: work situation

Cassie
I am currently 10w2d pregnant after a miscarriage in April. I work in a day care with what's supposed to be 21/2 to 3 yr olds but lately they stick me with the worst kids in the day care, 12 of them, and they fight an don't listen. (It's not that I'm a weak teacher but their teacher lets them do away with whatever they want and I keep order in my room)
So if I try to be stern with any of them they try to swing on me and kick at me. 
I'm worried that one day a kid is actually going to hit me hard enough to kill my baby. My boss knows I'm pregnant and is working with me with appointments and stuff but I'm not sure she understands that I can't take the risk
If it comes down to my job or my child I'll pick my child. But my husband and I really need me working cuz he just started a new lesser paying job than what he had. So I don't know what to do.