Bals-Pratsch et al. write in their Letter that the increased obstetric risks in pregnancies with assisted reproductive technology (ART)—such as preterm birth and altered birth weight—could also be due to an increased prevalence of polycystic ovary syndromes and abnormal glucose metabolism in the mother. We agree with the authors. However, the increased obstetric risks cannot be attributed solely to these factors.
Results arguing against this come from the data of the Nordic countries presented in our publication, which report a decrease in obstetric risks from 2003 to 2007 as compared to previous years, whereas the prevalence for PCOS should not have decreased (1). The fact that the preterm birth rate for children conceived by ART was higher than that for children spontaneously conceived for the same mother also argues against this (2). However, we agree with Bals-Pratsch that for women undergoing ART, the indication for determining and treating an abnormal glucose metabolism should be less restrictive in order to reduce obstetric risks.
In his Letter, Wenderlein addresses the increased risk of cardiovascular abnormalities in ART-conceived children. He refers to the Swiss working group led by Scherrer et al., which in a report from 2018 compared 54 ART-conceived children to 43 non–ART-conceived children (with an average age of 16.5 years) and found that the ART-conceived children had an increased carotid intima-media thickness and an increased pulse-wave velocity (3). Of course, these studies must be taken seriously. However, according to an Australian study published in 2019, no such changes were found in 193 ART-conceived individuals as compared to 86 non–ART-conceived individuals with an average age of 27.0 years. It is also noteworthy that, according to a meta-analysis, blood pressure in ART-conceived children born after the turn of the millennium is no longer found to be elevated as compared to older age groups (4). Thus, after the initial troubling study by Scherrer et al., large studies carried out in the meantime have not found any increased cardiovascular risks.
However, we agree with Wenderlein that ART-conceived children should continue to be examined, which is why we are currently preparing such a study with the Swiss cardiologists.
Finally, Wenderlein asks whether the risk of cancer in ART-conceived children is increased. The meta-analysis by Gilboa et al. (5) provides a clear answer: the risk is not increased.
Footnotes
Conflict of interest statement Prof. von Wolff has received consultancy fees from Merck Serono and Ferring, reimbursement of congress fees and travel expenses as well as study support (third-party funding) from IBSA Institut Biochimique, and lecture fees from TEVA, Theramex, and Ferring. He heads the IVF-Naturelle Competence Network.
Prof. Haaf declares that no conflict of interest exists.
References
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