Data revealed major birth defects in 90 of 1,462 IVF-conceived children, 17 of 343 children conceived through intrauterine insemination or IUI (a less complex procedure in which sperm is injected into the uterus to fertilize an egg) and 369 of 8,422 naturally conceived children. The comparative birth defect rates were: 6.2 percent for IVF babies, 5 percent for IUI babies and 4.4 percent for naturally conceived babies.
Van Voorhis said the team studied babies born from assisted production procedures aside from IVF to help determine if the increased rate was associated with the IVF procedure itself or factors in couples being treated for infertility.
He explained, "Had we seen lower risk for IUI-conceived babies, suggesting that another form of assisted reproduction had no increased risk compared to natural conception, it might have pointed toward IVF as a culprit. But the risk of major birth defects was slightly higher for IUI babies than for those naturally conceived.
"Had we seen a higher risk rate for IUI than for IVF, we would have thought there were issues with the couples being treated rather than with the IVF procedure itself. Yet the IUI rate was in between the rates for IVF and natural conception, so it remains unclear. IVF babies may have increased risk partly due to procedures and partly due to conditions affecting the parents who come to us as patients," Van Voorhis added. "We are not trying to assign 'blame' for the problem but rather are hoping to pinpoint areas of the IVF treatment that could be changed to improve the safety for children."
While the team had the advantage of using one of the most comprehensive and respected birth defect registries in the nation, it would take a much larger study involving multiple states and registries to answer questions about
Contact: Becky Soglin
University of Iowa