[wayward]

In Humanae Vitae, after the Pope reaffirmed the ban on contraception, he urged scientists to continue researching and improving natural methods. Some Catholic scientists and Catholic universities (Creighton, Marquette, Georgetown, etc.) took him up on it. This is not to belittle non-Catholic contributions, but that's a big reason why so much of the research is from Catholic sources.

(FWIW, the Catholic Church does not consider FABMs to be contraception, but "well-timed abstinence". Some of the Catholic sources can be really confusing if you're not aware of this terminology.)