Progesterone elevation on the day of HCG administration may affect rescue ICSI.

To investigate the relationship between serum progesterone concentration on the day of human chorionic gonadotrophin (HCG) administration and rescue intracytoplasmic sperm injection (ICSI), a total of 9858 patients who underwent IVF or rescue ICSI were retrospectively analysed. The results showed a significant difference in serum progesterone concentration on the day of HCG administration between the IVF group and rescue ICSI group (P < 0.01). Multivariate logistic regression showed that progesterone concentration was positively and significantly associated with rescue ICSI (OR 1.297, 95% CI 1.153-1.460, P < 0.001). Moreover, an increased rescue ICSI rate was associated with progressively higher progesterone concentrations in all cycles. In addition, patients with progesterone >1.5 ng/ml demonstrated a significantly higher rescue ICSI rate compared with patients with progesterone concentration ≤1.5 ng/ml (P < 0.05). In conclusion, elevated progesterone on the day of HCG administration had an adverse effect on oocyte fertilization; thus, greater attention should be paid to these patients in an attempt to avoid fertilization failure, especially when progesterone is >1.50 ng/ml. For the issue of oocytes fertilization, most literatures have found the presence of a negative association between P elevation and fertilization. They suggested that P elevation may only influence the endometrium, leading to impaired endometrial receptivity and had no adverse effect on the fertilization of oocytes. On the contrary, we enrolled 9,858 fresh cycles and found elevated P had an adverse effect on the oocytes fertilization, especially if the P concentration >1.50 ng/mL. It is the first report about the relationship between the rescue ICSI and serum P levels.