A new study by researchers from the Centers for Disease Control and Prevention finds that use of intracytoplasmic sperm injection – an assisted reproduction technique for male infertility – doubled between 1996 and 2012, though the method was no more effective than conventional in vitro fertilization.
Intracytoplasmic sperm injection (ICSI) was first introduced in 1992 for the treatment of sperm-related infertility problems.
As opposed to conventional in vitro fertilization (IVF) – where a number of sperm are combined with a mature egg in a laboratory dish – ICSI involves injecting a single sperm into a mature egg before transferring the fertilized egg, or embryo, into a woman’s uterus.
ICSI may be performed if a man has a low sperm count, his sperm has abnormal shape or poor motility or previous IVF attempts have failed or shown a low fertilization rate.
According to the researchers, including Dr. Sheree L. Boulet of the Division of Reproductive Health at the Centers for Disease Control and Prevention (CDC), ICSI is much more expensive than traditional IVF, and it also poses a higher risk of transmitted genetic abnormalities.
“Pregnancies resulting from the use of ICSI have been associated with 1.5-4 times increased incidences of chromosomal abnormalities, imprinting disorders, autism, intellectual disabilities and birth defects, compared with pregnancies resulting from conventional IVF,” the team notes.
Still, past research has indicated that use of ICSI appears to be increasing in the US, despite there being insufficient evidence to suggest it is more effective than traditional IVF.
In this latest study, published in JAMA, Dr. Boulet and colleagues set out to gain a better understanding of the trends and effectiveness of both ICSI and conventional IVF use in the US.
By analyzing 1996-2012 data from the US National Assisted Reproductive Technology (ART) Surveillance System, the researchers identified 1,395,634 fresh IVF cycles – fertilized eggs that had been transferred to the uterus without being frozen first. Of these, 908,767 (65.1%) cycles used ICSI and 486,867 (34.9%) used conventional IVF.
Male factor infertility – defined as “infertility due to abnormal semen characteristics, abnormal sperm function or surgical sterilization” – was identified in 499,135 (35.8%) of fresh IVF cycles.
Cycles without male factor infertility – patients with unexplained infertility, two or more prior ART cycles with prior live birth, low oocyte (immature egg) yield, use of preimplantation genetic testing and female patients aged 38 years or older – accounted for the remaining 896,499 (64.2%) fresh IVF cycles.
Overall, the use of ICSI more than doubled in the US between 1996 and 2012, from 36.4% to 76.2%. Among the cycles with male factor infertility, ICSI use increased from 76.3% in 1996 to 93.3% in 2012, while ICSI use increased from 15.4% to 66.9% in 1996-2012 among cycles without male factor infertility.
The team found that in the presence of male factor infertility, reproductive outcomes of fresh IVF cycles using ICSI were similar to outcomes of cycles using conventional IVF. Among cycles using ICSI without male factor infertility, the team identified “small but significant” reductions in implantation, pregnancy, live birth and multiple live birth, compared with cycles using conventional IVF without male factor infertility.
Commenting on their findings, the researchers say:
“The results of this analysis demonstrate a steady increase in the proportion of ART cycles involving ICSI performed in the US from 1996 through 2012.
Compared with conventional IVF, use of ICSI was not associated with improved reproductive outcomes irrespective of male factor infertility diagnosis.”
The team says their findings are subject to some limitations. For example, they note that the US National Assisted Reproductive Technology Surveillance System does not gather information on fertilization rates, and ICSI is expected to perform better in this area than traditional IVF.
“Although we were able to indirectly assess fertilization failure using the number of cycles canceled following oocyte retrieval, this measure assumes that cycles not proceeding to embryo transfer represent those in which all oocytes failed to fertilize, which may not necessarily be true,” the researchers explain.
In addition, they point out that their analysis was limited to fresh IVF cycles, although they say it is “unlikely” that the use of frozen embryos would have affected the results.
Last month, Medical News Today reported on a study published in the journal Cell, in which researchers detailed the successful creation of primordial germ cells – precursors to egg and sperm – using human embryonic stem cells and adult skin cells.
The researchers of that study, from the University of Cambridge in the UK and the Weizmann Institute in Israel, say the development could improve fertility treatment and even lead to new treatments for age-related diseases.