NC for this as sure I'll get jumped on.
I sort of did this. Not lie as such, but my child's father never asked about contraception, never asked if I was on anything, never used anything himself. He'd probably say I tricked him but he never ever asked, clearly just assumed and never took any responsibility for contraception on his side.
At the time I was in my 30s and open to having a child. I was blinded by love possibly too? Hard to explain, maybe it was hormones? Like totally in a haze of not thinking thought the potential consequences of having a child that wasn't planned on both sides. I just thought, if it happens, it happens?
As it was, without contraception, it took over a year before I was pregnant. It popped into my mind throughout that maybe I couldn't have kids, so I was actually shocked when it happened in a way.
But all accounts he's a good Dad. And when it happened and he said "but I thought you'd be on something!", and I explained "no, never, and you never asked?", he actually accepted that and accepted responsibility for his own actions.
We both adore our child, thought I accept it was probably wrong to never broach the subject. He also appeared madly in love at the time and regularly said he wanted marriage and children with me. Maybe that swayed my thinking at the time too.
Just thought I'd give some perspective from experience.