Anal? :/

Hey guys...I am 5 weeks 3days. My husband is having a hard time with the things I "cant" do..he hasn't said anything, but his expressions show it when I tell him some things are not safe for a baby. This is our first and was a big suprise to us...so it's taking a little time to set in for him. We have anal sex very occasionally, and he asked me to last night and I told him no because I'm constantly constipated now...and I knew it would hurt my stomach...but is that even safe for the baby? I looked it up and it seems there's lots of mixed opinions. Have any of you guys asked your doctor or had previous pregnancies and had anal sex?