Infertility Treatments May Raise Birth Defect Risk
Study Finds Certain Kinds of Assisted Reproduction Are Linked to Higher Rates of Birth Defects
Tracking Birth Defects After Fertility Treatments continued...
Overall, the study found that the risk of any birth defect in pregnancies involving assisted conception was 8% compared with 6% in babies conceived without assisted techniques.
The risk of a birth defect after IVF was 7%. The rate of birth defects associated with ICSI was higher at 10%.
For IVF, doctors mix a woman's eggs and the male's sperm in a petri dish and later implant these into the female. In ICSI, doctors inject a single sperm directly into an egg to fertilize it. Resulting embryos are then placed into a woman's uterus or can be frozen for future attempts.
One important point: When the doctors adjusted their data to account for a host of medical conditions and circumstances that are known to raise the risk of birth defects, like the mother's age and a history of smoking, the increased risks associated with IVF largely went away -- suggesting that the procedure itself was not to blame.
Birth defects associated with ICSI, however, remained 55% higher than the rates seen in fertile couples even after researchers took into account underlying factors associated with birth defects.
Despite the apparent increased risk, "people getting ICSI shouldn't be immediately alarmed," says Davies.
"The [newest] data in the study are now 10 years old, and in that time, there have been dramatic improvements in implantation rates in ICSI, which I take to mean that embryo quality has improved over that time. So it could be that we're looking at a historical snapshot and technology has overtaken it somewhat," he says.
Freezing Embryos May Lower Birth Defect Risk
In looking even more closely at the numbers, Davies says there also seemed to be a difference in the risk of birth defects depending on whether doctors were working with fresh, as opposed to previously frozen, embryos.
Babies conceived from embryos that were frozen after ICSI have a risk of birth defects that's nearly the same as that of babies born to fertile couples. Whereas babies that started as fresh embryos had a risk of birth defects that was about 75% higher than those born to fertile couples.