His pregnancy sex drive

Ok so I have a question. My boyfriend and I recently found out we are expecting, and prior to this we had sex like once or twice a week. Since finding out, we have been having sex everyday sometimes multiple times a day. Its literally anytime he rubs my belly he gets excited. Is this normal? I have never seen anything like this. Im not complaining, I love the increased sex, but it did confuse me. Checking to see of anyone else has gone through this.