Why?

Just wondering if I'm the only one that ever wonders this.
Now let me start by saying that I have no problem with the naked human body. I'm an artist so I've had to look at my fair share of them when looking for some good referenaces etc etc.

But why do pregnant women feel the need to get naked and take a photo of their big naked baby bump bodies?
Well, I get that they probably feel beautiful, and they are in their own way. But I dunno, it just seems weird to me for some reason lol.
Not saying that they shouldn't do it, but I just don't like looking at it. I don't have a problem with the baby bump part. It's the breasts that bother me.
Now I don't have a problem with breasts in general. Most of the time they're beautiful, and they're fun to draw, but when it's a pregnant woman's big swollen breasts w/ the HUGE nipples... it weirds me out.
There's really no reason, just one of those unexplained things that bother me.

It's like whenever I've watched videos of labor, specially water births or photos of it. I don't want to see them pushing while they're huge boobs are hanging all out.
Maybe its my repressed US mentality of breasts=sex... who knows. I'm sure I'll get over it whenever I get preggo.