**3.1. History taking**

Menstrual abnormality such as oligo-anovulation (OA) is usually noted [32]. According to the Rotterdam criteria, OA is defined as less than eight episodes of menses a year or cycle lengths of more than 35 days [5]. A stricter definition, such as less than eight menstruations and/or two cycles of less than 22 or more than 42 days per year, the prevalence of OA drops to 14% and OA becomes highly predictive of PCOS [33, 34]. Although 30% of women with PCOS will have normal menses [2, 35], 85–90% of women with OA have PCOS, while 30–40% of women with amenorrhea have PCOS [2, 36]. After the age of 40, women with PCOS often have more regular menstrual cycles while women over 30 who develop OA are less likely to have PCOS [32].

Weight gain and central obesity are common presentations in PCOS and usually come before the onset of anovulatory cycles [14]. In the United States, the prevalence of obesity in girls aged 12–19 years in 2007–2008 was 17%, compared with 50–80% among adolescent girls with PCOS [13, 37–40].
