Need help!

I think my 9yr old is acting out because im pregnant. He has never acted like this until a month ago . I'm almost 7 months pregnant and my son (9) has recently started talking back , disrespecting everyone and getting into trouble in school . I'm at my wits end I don't like to spank him so I ground him but it feels as if he is alway grounded now . I ask him what's going on and he tells me I shouldn't care about him anymore or leave him alone . I reassure him I love him and he will alway be my baby and no matter how may kids I have he will alway be my heart . I spend time with him cuddle with him play with him all the time . I don't know what I should do please someone help me figure out what is going on.