I also had a visa geezer as an early 20s, good looking woman.
He was already married for a visa (a fact he "forgot" to tell me) but was unhappy with how that was working out (very difficult culture/language for someone not from there to do well especially if a different race).
So (because he couldn't go for the marriage approach with me) he tried for the "child with a UK/EU citizen approach" (which used to get the parent at least 18 yrs in the UK, I think, and the possibility of indefinite leave to remain. Not sure what the case is now).
For various reasons (he thought I was leaving pretty soon, he was just incapable of having the patience and "intelligence" and putting in the effort for a long con, and he probably could not afford/didn't want to pay out 1k a pop flights to the UK & back to continue the con), he went in for the kill , suggesting we have a baby, proposterously early ... Like 3/4 months of dating max.
I was totally non plussed. At the time, I didn't know he was married, didnt realise the visa angle, and just thought it was bizarre ..the only explanation that even occurred to me was because (he said when asked) he had no kids and was hitting his 40s; that he had become increasingly dissatisfied and self conscious about that and was rushing into it (he was from a developing country with a culture of having kids young and men having kids by multiple mothers/polygyny).
I was so green, it didn't even occur to me that he might tamper with the condoms; which I was obviously relying on for std prevention as well as pregnancy prevention. I don't know if he ever did, but I did experience a delayed period with an extremely painful onset - perhaps a very early miscarriage - which I'd never had before or since.
When it became clear I was not remotely up for having a baby, I wanted to use condoms all the time, and I would seek a termination if I fell pregnant; he moved on. I bumped into him in a venue I'd taken him to (not in his town) on a double date with other EU national women.
Anyway... My long-winded point is; visa geezers etc will have a go at anyone - including young women, very attractive women; their chances of success are probably lower with these groups though.