What are the best NATURAL birth control practices?

With no side effects?

It is known that heating the testes makes men infertile, and for this reason was once a popular method.

My biggest problem with this method is its feminizing impact on testosterone levels.

But what if cooling below the temperature of healthy sperm production doesn't harm testosterone levels? Why are there no published articles about it and do any of you have any experiences to share?

I could only find some information on beetles and their sperm and testes at temperatures below 30°C.

What are the best NATURAL birth control practices?
What are the best NATURAL birth control practices?
Updates
10 mo
I will not let go of promoting testicular refrigeration. There were these statistics: www.auajournals.org/.../JU.0000000000001546 that showed negative correlation of testosterone to temperature, as well as light hours. That's supposed to surprise you. Because in mammals sun stimulates hormone production and often triggers reproduction. It could be that most people are deficient in healthy fats and eat more fatty, warming foods when it's cold? Or is it testicular temperature?
Updates
10 mo
Here was another useful page: academic.oup.com/jcem/article/88/7/3099/2845254
The only studies that showed T levels peaking in summer, included very young people, one was with 19 year olds in the mix and the other only 6-12 year olds. But young people eat more junk food on Christmas, hence they lose in winter. Also in studies of testicle boiling, the ages around puberty did not lose testosterone when their testicles were heated. Only adults lose T as a result of testicular overheating.
Updates
10 mo
Today I joined a conversation about weighted vests, some people wear hundreds of pounds for fitness reasons. And I thought, these cheap lightweight stationary semiconductor heat pumps are much less efficient than compressor type freezers. And not only will I be saving electricity bills if I switch to compressor type testicle coolers, but I might switch to dirt cheap lead-acid batteries instead of lithium type, and by this I'll add weight, a backpack full of lead like a training vest to keep fit.
Updates
10 mo
I found a peer reviewed study, discussed thoroughly by the highest ranking medical authority, EXACTLY about testicular cooling and at which points sperm is damaged and at which temperature testosterone levels are still maintained: https://m.youtube.com/watch?v=DVOKswJdH-Y this is the best, most life changing scientific video I've ever watched.
Updates
8 mo
Why doesn't anyone call me a "troll"?
Updates
8 mo
Did you know: penntoday.upenn.edu/.../frozen-testicular-tissue-still-viable-after-20-years
After being transferred to an infertile mouse, testes tissue from a rat that had been frozen for more than two decades gave rise to sperm and germ cells.
What are the best NATURAL birth control practices?
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