A US study has found that despite increased use of intracytoplasmic sperm injection (ICSI) over recent years, the technique is not associated with any improved reproductive outcomes over conventional IVF.
The findings, published in JAMA, also indicated that ICSI might even have a detrimental effect in cases without male infertility.
ICSI is an adaptation of IVF, introduced in 1992, in which a single sperm is injected directly into the egg, which was developed primarily for use in cases of male infertility, such as low sperm count or poor sperm motility.
Using data from the US National Assisted Reproductive Technology Surveillance System, the researchers found that between 1996 and 2012, the incidence of ICSI during fresh IVF cycles more than doubled from 36.4 percent to 76.2 percent. The greatest increase was in cycles with no male infertility where ICSI use rose from 15.4 to 66.9 percent .
Using data for the 2008 to 2012 period, the researchers indirectly estimated fertilisation rates by looking at the number of cycles cancelled following oocyte retrieval. This indicated that, when male infertility was present, ICSI led to an increased likelihood of fertilisation compared with conventional IVF. But they also found that the reproductive outcomes - including pregnancy, miscarriage and live birth - of traditional IVF and IVF using ICSI were similar in cycles with male factor infertility.
Furthermore, in cycles without male factor infertility, the use of ICSI resulted in 'small but significant' reductions in implantation, pregnancy, live birth, multiple live birth and low birth weight rates compared with conventional IVF.
The researchers from the Centers for Disease Control and Prevention in Atlanta comment: 'Although such differences may be a function of the large sample size and thus not clinically relevant, our findings suggest that use of ICSI may improve fertilisation rates but not implantation or pregnancy rates in the setting of unexplained infertility, advanced maternal age, and low oocyte yield.'