They are indeed beautiful in addition to their innate beauty. When I see one, I am reminded of what I experienced with my wife, and so well expressed in the song, "Green Fields Of Summer" They sang, "It was good to be young then, to be close to the earth, to be standing by your wife at the moment of birth." A situation that has bonded me with my wife and children for life.
I whole-heartedly agree with you. And like the photos you posted, I find photographs of pregnant women to be particularly beautiful.
When I got pregnant I knew my husband would be frustrated with abstinence... So I put him in a chastity belt... immediately. I let him nurse at my milkjugs daily and bring me off orally. But his ejaculate is for one purpose only. I control that! If and when I am ready for another child I know where the key is.