J Clin Endocrinol Metab. 2009 Apr 7; Kuijper EA, Vink JM, Lambalk CB, Boomsma DIIntroduction: Intra-uterine androgens of a male fetus may influence the female fetus in opposite sex-twin pairs. As female intra-uterine overexposure to androgens could lead to polycystic ovary syndrome, the prevalence of PCOS should be higher, in women from dizygotic opposite-sex twin pairs. Therefore, the aim of the current study was to evaluate the prevalence of polycystic ovary syndrome in women from opposite-sex twin pairs compared to women from same-sex twin pairs, sisters and female spouses of twins. Subjects and Methods: Data from 1325 monozygotic twins, 1191 dizygotic twins (711 women from same-sex twin pairs and 480 women from opposite-sex twin pairs), 745 sisters of twins and 218 spouses of male twins were evaluated. PCOS was defined as less than nine natural menstrual cycles a year combined with either hirsutism or acne. The prevalence of PCOS was compared using a chi-squared test. Binary logistic regression analyses were conducted to test for confounding effects of smoking, age and BMI. Results: No significant differences in PCOS prevalence were found between women from same sex twin pairs (either monozygotic or dizygotic), opposite-sex twin pairs, sisters and spouses. Conclusion: The prevalence of polycystic ovary syndrome is not different in women from opposite-sex and same-sex twin pairs, singleton sisters or spouses. This indicates that possible androgen exposure of the female fetus, caused by a shared intra-uterine environment with a male fetus, does not result in PCOS-like traits.
