Since hormonal birth control is much more common in Europe than in the US, that would seem to hint that uterine fibroids are not directly linked to hormonal birth control.
On the contrary, the pill seems to help prevent them instead[1].
When I lived in Canada I was always surprised how much people seemed to fear the pill when it has been something completely normal in Europe for two generations already. I'm still not sure why there is this difference of attitude between the two sides of the Atlantic.
However, it takes little effort to find contradictory information on the subject via google:
"Medical practitioners believe and research has recognized the increased levels of estrogen generated by the body preparing for pregnancy and preventative medicines like birth control have a correlation between the cause and effect of uterine fibroids."
"There are two major components known for stimulating the growth of fibroids; estrogen and progesterone. Birth control pills contain both of these elements causing the medical industry to take additional steps in studying the levels of estrogen and the potential rate of fibroid enlargement caused by a women’s use of prescribed birth control pills."
taken from https://fibroids.com/blog/fact-fiction-birth-control-can-cau...
Considering the amount of revenue hormonal birth control generates for pharmaceutical companies, it would not surprise me in the least to discover behaviors resembling the tobacco industry's misinformation campaigns to protect those revenues.
"Contraceptive pills is identified to be the most lucrative product segment in the contraceptive drugs market, estimated to grow at a CAGR of 5.3%, from 2016 to 2023. The industry is majorly driven by the presence of favorable government initiatives and regulatory framework."
https://globenewswire.com/news-release/2016/05/19/841462/0/e...
I recall when my wife was moved to the generic the out of pocket cost was like $8, which was under the copay. The pharmacist said that the placebo pill that is there for the last days of the cycle was more expensive than the actual drug!
"The uterus is good for two things, growing babies and growing tumors."
Apparently these are extremely common, and hormonal birth control exacerbates the problem by making the body behave as if it's constantly pregnant. Both of my friends were angry about having been casually prescribed birth control pills as teens without being clearly informed of it increasing the probability of this outcome.
[1] https://en.wikipedia.org/wiki/Uterine_fibroid