What your opinion about how much weight to lift?

So I just found out I'm pregnant 2 days ago. I'm a preschool teacher for 2-3 year olds and I have a 17 month old. 
I remember when I had my baby girl I couldn't lift much weight at the beginning. Should I still not lift much now? Or is it okay for me to lift my kiddos up still? 
I'm going to the doctor tomorrow