This isba question similar to one I had posted previously. 

I'm interested in the different reasons between men and women as to why each has this attraction/fetish/admiration. 

What are the reasons for you? And feel free to go in depth if comfortable doing so because for several (including myself) there are many layers to this.

For me it is quality of sex, plus the fact I cum through condoms so before I met my wife it was a way to have sex and prevent unwanted pregnancies if I did a pregnant woman

I honestly couldn't tell you why exactly; however, I would guess one possible reason is seeing the transformation a woman goes through is attractive to me. The starker the difference between a woman before pregnancy and during the better in my opinion. One thing I could tell you though is that on account of this particular fetish I've developed a few others over the years.