u/DifferentDirector2

I apologize, really struggling to word this question right.

We now know (due to science) the best time period (as far as menstrual cycle goes) to have sex in order to conceive children. Do we know if this knowledge was ever reached before the 20th century? I imagine some 95 year old Russian grandma cracking the code in 14th century Europe and helping all the newly married women in her village conceive as quickly as possible but I have no sources to back up this hypothesis.