Intracytoplasmic morphologically selected sperm injection is beneficial in cases of advanced maternal age: a...

To evaluate advanced maternal age as a rationale for performing intracytoplasmic morphologically selected sperm injection (IMSI).

This study included couples undergoing intracytoplasmic sperm injection (ICSI) as a result of advanced maternal age (≥37 years old). Sample size calculations were based on the assumption that a 15% difference in implantation rate would mean a clinically significant difference. To achieve this difference, 33 cycles would be needed in each treatment arm (with a significance level of 5% and power of 85%). Couples were randomly allocated to one of two sperm selection procedures (ICSI, n=33; or IMSI, n=33). Sperm selection in the ICSI group was analyzed under a magnification of 400×. Sperm selection in the IMSI group was analyzed under high magnification of 6600×. The groups were compared with regard to the outcome of the cycles.

IMSI cycles showed significantly higher implantation (4/33, 12.1% vs. 18/47, 38.3%, p=0.026) and pregnancy (4/29, 13.8 vs. 18/30, 60.0%, p<0.001) rates. The IMSI procedure positively influenced the blastocyst formation rate (RC: 15.00, R2: 49.9%, p=0.001) and implantation rate (RC: 24.04, R2: 9.6, p=0.027), and was determinant to the increased odds of pregnancy (OR: 9.0, CI: 2.17-37.38, p=0.001).

It seems that the injection of a morphologically normal spermatozoon overcomes the low oocyte quality in older women, resulting in improved embryo quality and in a 9-fold increase in the clinical pregnancy rate in couples with advanced maternal age.