IGF1 and polycystic ovary syndrome: We observed that genetically predicted each 1-SD higher risk of PCOS was positively associated with an increased risk of ER by 16.8% [IVW: OR 1.168 (95% CI: 1.020–1.337), p = 0.024], age at menarche by 11.7% [IVW-multiplicative random effects: OR 1.117 (95% CI: 1.058–1.179), p < 0.001], age at menopause by 56.9% [IVW-multiplicative random effects: OR 1.569 (95% CI: 1.129–2.180), p = 0.007], and IGF-1 by 2.9% [IVW-multiplicative random effects: OR 1.029 (95% CI: 1.004–1.154), p = 0.024].