Getting hips back in shape

I am currently in my third trimester and my butt has gotten humongous. I went from 36'' to like 44" I think. I used to wear a Small size 3 underwear, now I am wearing an XL 8. My butt is honestly bigger than my belly right now. I am mostly not able to fit in my old clothes because of my butt rather than my belly.

I know this happens to a lot of moms when pregnant, I was wondering if there is any hope of going back to my old butt. I have seen a lot of ladies in my family be stuck with a big butt forever after having kids, and I really don't want that.

Any tips or tricks on what to do after I have the baby? My mom said it's not advisable to start dieting or jump into an exercise routine the first four months after having the baby, but I am really so self conscious about it right now, it doesn't help that my husband (jokingly) said today that I look like an elephant from behind 😢