Conception isn’t painful; it happens within seven days of a sexual intercourse, and the woman has NO IDEA when. There can be an egg already waiting in the Fallopian tubes, or the ovulation happens days after the intercourse. The sperms can live inside for up to seven days.
CHILDBIRTH is painful, yes, both for the mother-to-be AND for the father-to-be. The expectant father can be in a lot of pain too, as he sees the love-of-his-life being in excruciating pain, and not able to do anything about it, except hold her hand and give her ice-chips.
Most of the times people have sex there is no childbirth afterwards. Stable couples probably have sex about once a week or so, but they seldom have more than three kids over a life-time.
Most people who get pregnant by rape terminate the pregnancy asap. Somehow, rapist dads are not known for their excellent parental skills…