Keeping it Current
Consistent with this goal of constant monitoring, a study was published by The New England Journal of Medicine (May 10, 2012) evaluating data from Australia about IVF and birth defects. What follows are quotes from that article where indicated. [Davies et al NEJM 2012: 366:1803]
“In this large observational study using detailed Australian databases with information on several potential confounders, we confirmed previous findings of an increased risk of birth defects among births conceived with assisted reproductive technology as compared with births from spontaneous conception. After multivariate adjustment, the association between IVF and the risk of any birth defect was no longer significant; whereas the increased risk of any birth defect associated with ICSI remained significant.”
The actual risk was given as a 5.7% risk of birth defects for pregnancies not involving assisted reproductive technologies. The risk for those involving assisted reproductive technologies was 8.3% before adjustment and 7.2% after adjustment. The first sentence of their conclusion is” The increased risk of birth defects associated with IVF was no longer significant after adjustment for parental factors.”
Understanding the Numbers
So how is one to interpret this? If there is an increase in birth defects for people using assisted reproductive technology to conceive, it is small and most of this increased risk can be accounted for by factors present in the parents. These factors are usually the reason for the need for IVF to begin with. Therefore, IVF seems safe.
Any person wishing to conceive runs a 5.7% risk of having a child with a birth defect. This is a changing number as well, as the statistic from the March of Dimes formerly quoted the risk of birth defects to couples NOT using assisted reproductive technology, as 3%. But, again as science and technology continue to evolve, and diagnostics improve in their ability to assess certain childhood conditions and illnesses and their relationship to the child’s DNA and that of their parents, the numbers change. And it is this number overall, that which affects parents regardless of their means of conception, that ultimately changes the ‘perceived risk’ of IVF.
Looked at in the worst case scenario, couples facing infertility severe enough to recommend IVF face an 8.3% risk of having a child with a birth defect, as compared to the 5.7% risk of those who conceive naturally.
With over 4 million children born though the use of IVF worldwide, these are reassuring if not absolutely comforting numbers.