Pregnant with a toddler who doesn’t listen

I’m 6 months Pregnant my son is going to be 4 in a month.

Ever since I was about 2 months Pregnant his behavior changed not only at home but at school

He has a hard time listening I’ve tried the time out method, taking toys , screen time away, spanking. I tried ignoring so he won’t get a reaction. I tried talking to him and NOTHING is helping everyone says it’s probably because you’re pregnant but I don’t understand

I’m going insane. at school he has a hard time listening to the teachers sometimes he’ll be doing great and during transition he he has a hard time he wants to throw tantrums in public now he never did that before .

He cries for everything now.

I know kids are kids but he’s doing things now he’s never done before.

Is this normal or ???