I read a report on this from the UN recently. I had a discussion with a person not too long ago where this person claimed that they were not against this due to the fact that males were required to have lowered their testosterone levels in order to compete in women's sports, so this person thought that that evens things out and everyone is equal.
The UN report specified that in order to compete in women's sports, males had to have lowered their testoserone levels to 4 (I don't know what unit of measurement 4 is). Then the report went on to say that women's average normal level of testoserone is 1.5. So, males are allowed to compete in women's sports, even though their testosterone levels are almost three times that of women. So, this shows that the playing field is NOT equal and is, indeed, unfair to women.