Is it because of the milky tits and hard round stomach?

There may be various reasons for it. A scientific theory is based around the fact that, during cavemen times and of course still today, a pregnant woman obviously shows fertility.
Her being pregnant shows that she is good for having children.
The trigger that lets us see a big round baby belly as sexy may come just from the fought that she would also be an ideal woman to breed future babies with.

........
But, of course it can be caused by other weird kinks too I dont really care, I just want to have sex with a preggo^^

(February 7, 2015, 3:14 am)Paradox There may be various reasons for it. A scientific theory is based around the fact that, during cavemen times and of course still today, a pregnant woman obviously shows fertility.
Her being pregnant shows that she is good for having children.
The trigger that lets us see a big round baby belly as sexy may come just from the fought that she would also be an ideal woman to breed future babies with.

........
But, of course it can be caused by other weird kinks too I dont really care, I just want to have sex with a preggo^^

Indeed, as such it might not be an actual fetish as it is basically what having sex is for ;-)

It is a question that can not answer clearly, even I was pregnant because I like, maybe it is somewhat difficult to explain

Pregnant women need to be loved and (real) men love to bang pregnant women.

It's perfectly normal.

Some weirdos don't like pregnant women. Shame because hot preggo women like (and need) to fuck all the time!

Pregnancy is the ultimate symbol of feminity (since only women get pregnant and give birth) and motherhood is a honorable, beautiful and powerful thing to have. Many men's instincts is to see a pregnant woman means she has sexual feelings...we want a fertile woman to bear our children and deep down, we admire female abilities to bring forth children for us, family and the world. What really gets me is I want to see women with big round bellies, also I'm fascinated to see stretch marks, linea nigra and varicose veins. I wanna tell her how beautiful she is and her body is in an interesting state for 9 months or 40 weeks (on average). And a large number of (but not all) pregnant women reported an increased libido or wanting to have sex, esp. the "honeymoon phase" of the second trimester. An expecting couple should discuss this issue on fulfilling romantic and sexual needs while she's pregnant, so things can go smoothly in the third trimester as well. And getting to rub her big belly can be a turn on for me (and her), but I also like to feel the unborn baby move or kick and hear its heartbeat...I'm human and I do care about children.