clear liquid coming out of my nipples

I'm sorry if this is a dumb question but I'm a first time mom I've never been pregnant before and everyone told me my boobs wouldn't leak or anything until after baby is here (I'm 19 weeks and 3 days pregnant) but there's this clear liquid that keeps coming out of my nipples (not tons at a time just a little at a time) but I'm confused on what this is or if it's even normal has this happened to anyone else???? Is it normal????