It is and isn't a kink for me, pregnancy has always been a huge fetish for me. When my wife and I were separated and she was seeing another guy, we started having some of the best sex we'd ever had. During that year, she turned up pregnant, we'd been trying before things went south for us and it just wasn't happening. SO, we both thought her boyfriend was the father but when the baby came out, a few things pointed the finger to me and a DNA test proved the ...... was mine (I was so very happy). I did, however, really get off on the thoughts of another man getting my wife pregnant (even though we were separated legally), I think at the time maybe we both liked the thought of it.
So she comes home and things go south again and she starts seeing someone else again, behind my back even though I said she could... and again she comes home. During this time, we started trying for another ...... so our youngest would have a sibling and we both made comments during sex that if I couldn't do the job, we might have to let "him" try. I was seriously all for it too but there was so much happening there that I don't think he'd have been up for that. So we didn't have another ......... she can't now... but if she'd start picking and playing about it if we ever have sex again, I'll be all up for going along with her on it.
Like it's already been said though, a ...... isn't a toy or something to use to fulfill a fetish/kink. It's a lifelong thing and a human with feelings.