There are several in vitro methods available to couples hoping to conceive a child. All are aimed at addressing fertility problems and one has been seeing increased use through the years: intracytoplasmic sperm injection, or ICSI.
Introduced in 1992, ICSI differs from conventional IVF in that a single sperm is injected into a mature egg. Singling out the best sperm possible for fertilization, the method is mostly aimed at addressing male infertility involving low sperm counts, abnormally shaped sperm or failed attempts at fertilization using conventional IVF.
Researchers from the Emory University School of Medicine and the Centers for Disease Control and Prevention analyzed data from 1996 to 2012 gleaned from the U.S. National Assisted Reproductive Technology Surveillance System.
Published in the Journal of the American Medical Association, their work identified 1,395,634 fresh cycles of IVF or fertilized eggs transferred immediately without being frozen first. Out of these, 34.9 percent (486,867) utilized conventional IVF while 65.1 percent (908,767) took advantage of ICSI. Additionally, 35.8 percent (499,135) of cases involved male factor infertility while the remaining 64.2 percent (896,499) were due to other infertility factors.
Though there appears to be a preference for ICSI, the method is actually no more effective than conventional IVF, when male factor infertility was in the picture. Without male factor infertility, cycles actually showed small but significant reductions in rates of implantation and pregnancy, as well as live births. Where more than one child is to be born, ICSI-related pregnancies also have a low rate for successful multiple live births.
And when successful, ICSI was still associated with other complications.
"Pregnancies resulting from the use of ICSI have been associated with 1.5 to 4 times increased incidences of chromosomal abnormalities, imprinting disorders, autism, intellectual disabilities, and birth defects compared with pregnancies resulting from conventional IVF," wrote the researchers.
The increase in risks may be due to underlying effects brought about by subfertility in the male or female, other medical conditions in the parents, or the ICSI procedure itself, which bypasses natural barriers to promote fertilization, leading to higher chances of genetic defects being passed on from one generation to another.
Researchers admit that their study had limitations (like the U.S. National Assisted Reproductive Technology Surveillance System did not include information about fertilization rates) so further research is recommended to explore the risks and benefits of ICSI.
The study was supported by the National Institutes of Health's National Center for Advancing Translational Sciences. Authors include: Sheree Boulet, DrPH, M.P.H., Akanksha Mehta, M.D., Dmitry Kissin, M.D., M.P.H., Lee Warner, Ph.D., Jennifer Kawwass, M.D., and Denise Jamieson, M.D., M.P.H.
