The 2nd phase: P (OHSS) = 1 / (1 + exp(- (- 1.7584 + 0.0276 * Female age - 0.3559 * Number of COS cycles - 0.3784 * Previous live birth (1) + 0.1989 * PCOS (yes) - 0.8059 * GnRH antagonist protocol - 0.1586 * Duration of Gn- 0.0126 * Initial dose of Gn + 0.0664 * Number of follicles (≥ 16 mm) on trigger day + 1.2158 * E2 levels on trigger day (3670 ≤ E2 < 18350 pmol/ml) + 0.8908 * E2 levels on trigger day (E2 ≥ 18350 pmol/ml) - 0.092 * P levels on trigger day + 0.0144 * BMI + 0.0028 * AMH))). This evidence concerns the gene GNRH1 and polycystic ovary syndrome.