In total, 655 women of reproductive age and European ancestry from the previously described Rotterdam PCOS cohort were included in this study (Day et al., 2018 (link)). The Rotterdam PCOS cohort, the CyclusOLigoAmennorroe (COLA) study, was approved by the institutional review board (Medical Ethics Committee) of the Erasmus Medical Center (04-263). PCOS was diagnosed based on the Rotterdam criteria requiring at least two out of the following three diagnostic criteria: (i) oligo- or amenorrhea, defined as chronic menstrual cycle interval >35 days or >188 days, respectively; (ii) clinical HA, defined as modified Ferriman Gallwey (FG) score above 5 and/or biochemical HA, defined as elevated (>4.5) free androgen index [testosterone × 100/SHBG] (Bui et al., 2015 (link)); and (iii) polycystic ovaries, defined as 12 or more follicles of 2–9 mm in each ovary and/or an ovarian volume >10 ml (Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group, 2004 ). Serum AMH levels were measured with the picoAMH assay [Ansh Labs®, Webster, TX, USA]. Serum testosterone was measured using radioimmunoassays (Diagnostic Products Corporation). Serum FSH and LH were measured using the Siemens Immulite 2000XPi, and total follicle count (TFC) and ovarian volume were assessed as described earlier (van Santbrink et al., 1997 (link); Kevenaar et al., 2008 (link)).