Associations of menstrual cycle irregularities with age, obesity and phenotype in patients with polycystic ovary syndrome.

OBJECTIVE: Limited data suggest that menstrual cycle abnormalities are more pronounced in younger and more obese patients with polycystic ovary syndrome (PCOS). We aimed to evaluate the association between menstrual cycle pattern and age, obesity and PCOS phenotype in a large population of women with PCOS.
DESIGN: We studied 1,297 women with PCOS and divided them according to: a) age in ≤ 20, 21-30 and > 30 years old, b) body mass index in normal weight, overweight and obese and c) PCOS phenotype in phenotype 1 (anovulation, hyperandrogenemia and polycystic ovaries), 2 (anovulation and hyperandrogenemia without polycystic ovaries), 3 (hyperandrogenemia and polycystic ovaries without anovulation) and 4 (anovulation and polycystic ovaries without hyperandrogenemia).
RESULTS: The proportion of women with regular menstrual cycles progressively increased in the older age groups, being 8.1, 10.5 and 12.7% in women ≤ 20, 21-30 and > 30 years old, respectively (p = 0.037). The proportion of women with regular menstrual cycles did not differ between normal weight and obese women but was higher in overweight women (9.3, 9.4 and 13%, respectively; p = 0.020). The proportion of women with regular cycles alternating with irregular cycles was highest in women with phenotype 4, intermediate in women with phenotype 2 and lowest in women with phenotype 1 (74.3, 69.4 and 61.7%, respectively; p = 0.027).
CONCLUSIONS: Menstrual cycle pattern is more irregular in women with the "classic" PCOS phenotypes than in phenotype 4 but appears to normalize with ageing. On the other hand, obesity does not appear to have an important effect on menstrual cycle pattern in PCOS.