As far as I know the Fathers knew nothing of sperm and egg. Are you implying that christians must never reason beyond 1,700 year old scientific bases???
I have to disagree with that (not to argue whether the Fathers were for or against NFP). I’m just saying they were more knowledgeable than we give them credit to have been. Sure, they didn’t attend Harvard, but what they did do is…
These people raised goats, sheep and camels. If they were slaves or servants, they tended their superiors’ horses and other animals. They were farmers and their livelihood depended on their farming skills. There was no Walmart or Kroger’s down the road for meat, milk, cream, butter and cheese. They had to be able to make a palatable product for themselves, their families and to sell to travelers if need be, and for their bosses. They knew when their animals were in heat, and when the time was right to breed them. I think you all are not giving them enough credit.
For example, a male goat in rut (wanting to breed) smells awful (for reasons that may be too much information to some folks on this forum). If your female goats are not separated from these males in rut, the milk they produce will be awful, just awful. Seriously, if a male goat in rut rubs up against a milking doe, that milk will taste like the buck and all his kinda gross deeds. If a milking doe
smells that buck, the same occurs. You must keep your does separated from your bucks by a good distance in order to produce a good product. If you don’t do this, the doe will take in the scent of the buck and as a result the milk, butter and cheese will have a gahd-awful taste. Therefore, a goat farmer worth his weight in salt will separate their bucks from their does. Not only that, bucks are a bit dangerous to handle sometimes, and they can challenge humans. Kids shepherded the flocks. Getting rammed by a ram or buck is dangerous, and they’re just mean sometimes.
Therefore, if you keep your bucks separate from your does, you need to recognize when your does go in heat, and bring your doe to your buck for breeding (or vice versa). They have average cycles, just like women. They go through changes, just like women. Their cervical fluid changes, just like women. Sure, women don’t do some of the outrageous things that mares, ewes, does or cows do (or maybe some of them do…it’s very difficult to abstain in a woman’s fertile time after all)… but that just makes them a little harder to read

but not impossible!
I do think these primitive folks did know a bit about a woman’s cycle. I’m sure they didn’t know all we know now. But I’m betting that if they saw signs of breeding readiness in goats, sheep, cows, horses, camels, etc, they were able to put two and two together with women as well. They really share a lot in common with women, including cervical fluid (one of the most important signs of fertility in women who are either trying to conceive or trying not to conceive).
Just saying… They weren’t as ignorant as we centuries-later folks think they were…