SHBG and polycystic ovary syndrome: Univariate regression analysis of the association between SHBG and pregnancy outcomes, folate metabolism status, and embryo transfer outcomes in PCOS patients before and after treatment revealed that SHBG is an independent risk factor for pregnancy outcomes, folate metabolism disorders, and overall pregnancy outcomes prior to treatment (HR: 1.01, 95% CI: 1.01-1.07, P = 0.004; HR: 1.02, 95% CI: 1.01-1.04, P = 0.008; HR: 1.03, 95% CI: 1.01-1.06, P = 0.004) (Supplementary Table S5).