Re: making a problem out of nothing 
Well, I’m sure you already realize that pregnancy brings on a whole bunch of hormone changes that you’ve never experienced before. And its also a well-known that fact that pregnant women can and do get insecure due to all the physical changes.
Going by your comments…it looks like you’re aware of the fact that you’re overreacting a bit. It doesn’t seem like you’re concerned about your husband cheating.
All this being said…I think the first thing for you to do is to realize and continue telling yourself that your husband is attracted to you and loves you (heck your pregnancy is a proof that your husband is attracted to you!).
Secondly…I don’t think its a bad idea to sit down with your husband and CALMLY let him know how you’ve been feeling. Do not blame or accuse him of anything. Simply let him know that you’re feeling a little more insecure due to the physical changes in pregnancy…and you’d appreciate him helping you through this process by being a bit more careful around other hot women.