STUDY QUESTION

Does ICSI improve reproductive outcomes compared with conventional IVF when used for non-male factor infertility in women aged 40 years and over?

SUMMARY ANSWER

There is no advantage of ICSI over conventional IVF in women aged 40 years and over when used for non-male factor infertility.

WHAT IS KNOWN ALREADY

The use of ICSI has increased dramatically in recent years and is being applied for indications other than male factor infertility. Currently, ICSI is used in 65% of IVF cycles in Europe and in 76% of cycles in the USA. Despite its increase use, there is no clear evidence of a benefit in using ICSI over conventional IVF. Older women undergoing infertility treatments are at an increased risk of having diminished ovarian reserve and lower oocyte quality, which could make ICSI the preferred insemination method in this group. However, studies that have examined the benefits of ICSI in this age group are lacking.

STUDY DESIGN, SIZE, DURATION: A retrospective, single center study included women, aged 40-43 years, who underwent IVF treatments for non-male factor infertility between January 2012 until June 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 745 women were included in the study. Of these, 490 women underwent ICSI and 255 women underwent conventional IVF. In order to be included in the study, women had to be at least 40 years of age at the beginning of ovarian stimulation and their male partner had to have normal sperm parameters according to World Health Organisation (WHO) fifth edition. Exclusion criteria included: more than three previous IVF cycles, a history of fertilization failure or low fertilization (<50%), the use of donor or frozen oocytes and the use of donor or frozen sperm samples. The primary outcome was the live birth rate. Secondary outcomes included fertilization rates, fertilization failure and embryo quality.

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline characteristics were similar between the two groups, except for the number of previous IVF cycles, which was higher in the ICSI group (1.0 vs. 0.6, P = 0.0001). Despite similar numbers of oocytes retrieved (7.2 vs. 6.5), when examining oocytes maturity (performed 2 h after oocyte retrieval in the ICSI group and after 18 h in the conventional IVF group), the conventional IVF group had a higher number of Metaphase II (MII) oocytes (6.1 vs. 4.7, P < 0.0001). The conventional IVF group also had higher numbers of zygotes formed (4.48 vs. 3.66, P = 0.001), more cycles with embryos transferred at the blastocyst stage (36 vs. 26%, P = 0.005) and more cycles where embryos were available for cryopreservation (26.4 vs. 19.7%, P = 0.048), compared with the ICSI group. The fertilization rates (64 vs. 67%) and fertilization failure (9.0 vs. 9.7%) were similar. After logistic regression analysis controlling for confounders, the live birth rates were similar between the groups (11.9 vs. 9.6%). Subgroup analyses of women undergoing their first IVF cycle and women with ≤3 oocytes retrieved did not show an advantage of ICSI over conventional IVF.

LIMITATIONS, REASONS FOR CAUTION: The retrospective nature of this study was a major limitation. The ICSI group had a higher number of previous IVF cycles, which could mean that ICSI was performed in poorer prognosis patients. Moreover, although this study is one of the largest studies to examine the question of whether ICSI is of value for older women with non-male factor infertility, based on a post hoc power analysis, it was still underpowered to detect differences in live birth rates, which can limit the conclusions of the study. Prospective studies are needed to confirm our findings.

WIDER IMPLICATIONS OF THE FINDINGS

The decision regarding performing ICSI should be based on sperm parameters and previous history. The use of ICSI for the sole indication of advanced maternal age shows no benefit over conventional IVF.

STUDY FUNDING/COMPETING INTERESTS: None.

TRIAL REGISTRATION NUMBER

N/A.