...Females could marry - legally, with or without parental consent - when they reached their twelfth birthday. The age for males was fourteen. Even before she had reached her teens, a girl knew that unless she married before she was 21, society would consider her useless, hence the yearning of female adolescence for the altar. Getting pregnant was one way to reach it. On Sundays, under watchful parental eyes, girls would dress modestly and be demure in church, but on weekdays they opened their blouses, hiked their skirts, and romped through the fields in pursuit of phalli. Another five centuries would pass before young women would so open in their pursuit of sex. (W. Manchester, A world lit only by fire: the medieval mind and the Renaissance )
Once the man was properly secured, they had a lot of fun in bed, thanks to the medical consensus of the day:
...medieval writes accepted the Galenic theory that both a male and a female seed were required for conception. They believed that there was some sort of female sperm which gave pleasure in its emission, and had some influence on conception and the development of the fetus. This view worked to the benefit of married woman's sexual pleasure, since men believed that to conceive their wives had to reach orgasm.
BTW, being caught did not mean marriage... well, there was a caveat -
...A common punishment for fornication [sex between unmarried partners] was 'abjuratoio sub pena nubendi', forswearing on pain of marriage: a couple who fornicated were were made to repeat marriage vows in the future tense. Under canon law, such vows, when followed by sexual intercourse, constituted valid and indissoluble marriage. Thus, if the fornicators were to repeat their offence, they would automatically be married. (RM Karras)
It is interesting how puritanical and libertine attitudes go in circles, chasing each other. Few people realize that tomorrow is going to be VERY different from today or that the bicycles have been invented many times over.