Also I heard that the Romans had forms of birth control... And alot of upper class families only had 1 or 2 kids as a result, as opposed to 20 kids like in colonial America.
If you're basing this on the ancient world then I can perhaps be of use.
Given the lack of medical knowledge, even amongst medical 'experts', there was limited understanding of the human body. Some experts believed that fertilisation occurred because the male seed rotted inside the female and a baby grew like a tree might grow out of fertile ground. Limited medical understanding also lead to high infant and maternal mortality rates, and because of this children were seen to belong not to the human realm, but the realm of the gods. As far as sources suggest there wasn't a great deal of attachment to children, hence why they exposed them.
The most documented method of pregnancy prevention was the old withdrawal method. Failing that, the woman was to shift her body so the male seed might not reach her own. Obviously this wouldn't work too well. There are examples of suppositories being used as a barrier method, these being made of everything from crocodile poo to honey, but they are not widely documented.
Most preventative measures occurred after intercourse when the female would either drink something cold and sneeze or she would jump up and down whilst kicking her heels against her bum.
Let's just say it was magic lest Bethesda should start implementing suppository shops in the next game...