It's important to remember that it's a sensitive subject for many people. And unlike other kinks, this one is so supremely sexually dimorphic. It's as different as Mars from Venus, and the reasons a partner may find it bad are different.
If you're female, the risk is the male partner, if they're a judgemental idiot or insecure, or perhaps just jaded, may be concerned that a woman with a pregnancy fetish may be interested in using reproduction to entrap them. I mean, it's only tangentially related to a pregnancy fetish, but related. In general a woman with interest in pregnancy is considered a prize, because in this politically charged world, emphasizing the genders for breeding can be seen as distasteful or shameful and sexist. It's not like a woman can run around sharing pregnancy with other people, they just act baby-feverish. Society considers that harmless at worst and adorable at best.
If you're male, the risk is you. A female partner may be concerned you'll try and get her pregnant, or run around on her wily nily impregnating anyone with their legs spread and uterus available. Or that you may creep on her friends. Or people in public. You'll need to bear in mind that they'll question your ethics or sanity and the depths of your perversion. So the trick is to defuse possible accusations and worst case logical conclusions before someone can even reach them.
In both cases, you run the risk of someone assuming you're a pervert with no self-awareness or self control. It's not a given, but it's a possibility, sooo.. tread lightly, and always remember that, worst case scenario, they may come to those judgemental and hostile conclusions, repeat them to your peer group and suddenly you're the odd-man out.
Some things to casually slip into conversation; you don't go 'hunting' to gawk at pregnant people in public (photography, other) you don't have any interest in kids at the moment, you're not a whatever-ethnic-background-you-are supremacist (that can be a source for some peoples interest in it, terrible as that is) and that the only real avenue for you to enjoy it is pornography, art, games, comics and erotica. Anything else unless you're interested in actually starting a family is not to your interests.
But the trick is not to overload the partner with all these checklist like things, but to reassure them if they have questions about the severity of your interest and the basis for it, what you like about it, whatPost too long. Click here to view the full text.