Centuries ago and an entirely different way of life, conception in the Middle Ages was largely a mystery. If a woman couldn't get pregnant, she was to blame. And like some cultures today, a son was highly prized.
The primary role of women in the 1600s was to bear children. Many women were pregnant every year, but a lot of babies didn't survive. A lot of women didn't survive childbirth either because of infections or hemorrhage.
There were a lot of myths around conception and fertility. It was thought to be important for both the man and the woman to have orgasms to promote conception. That's not necessarily a bad idea, but, of course, we know now that it's not required.
They also didn't know that much about female anatomy. One reason is that it was not acceptable for men to examine women who were not their wives. Women were cared for almost exclusively by other women--midwives and maids. Another reason is that women were considered inferior to men, and so there simply wasn't much focus on women's health.
However, they were pretty obsessed with menstruation and whether a woman's cycles were normal or not. Menstruation was a way of cleansing the body of "bad humors," or poison, and so it was quite important. It was thought that older women who were past menopause harbored a lot of "poison." For that reason, they typically weren't treated all that kindly.
They also thought that what a woman was thinking affected the baby. To have a boy, women were encouraged to think about boys and men. Of course, they didn't know that gender was determined at conception, not sometime later in pregnancy.
One of the truly funniest concepts I have ever come across is one that Hippocrates wrote--that the uterus "wandered." This was used to explain all sorts of diseases. Also, doctors back then thought that there was only so much energy in a person, and if one area was overdeveloped, it took away energy from another area. That was the justification for why women should not be educated; mental development would take away from reproductive ability. Gosh, does that mean that women "educated themselves" out of the man-market even back then?
We know a lot more now, but some things are still a mystery, like why conception happens sometimes and why at other times it doesn't.