I am starting to doubt progesterone supplementing in pregnancy since I know someone who took natural progesterone and it made her spot during early pregnancy. This study claims that adults whose mothers took progesterone in pregnancy are more likely to be gay or bisexual. I was under the impression that excess estrogen from plastics and whatnot (especially during critical stages of development) caused homosexuality and gender dysphoria. I would like to know how homosexuality develops and can be prevented or mitigated hormonally. Progesterone and bisexuality: Is there a link?