Introverted husband and extroverted family

My husband is very introverted and has a hard time being with my very close and extroverted extended family, he’s just more comfortable at home. I end up going to a lot of family stuff with just me and my baby. I’m fine with this but I get a lot of questions from my family about why my husband isn’t there with me. I don’t want to sound like my husband doesn’t like them or is trying to be rude by not coming. What can I tell them so they can understand that it’s just what highly introverted people do