(RxWiki News) In vitro fertilization (IVF) has helped women around the world become mothers. This technique that’s been used for years can result in more than one bundle of joy. A new study discovered that multiple births after IVF might have risks.
A new European study found that women who gave birth to multiple children after IVF therapy were at higher risk for breast cancer compared to women who had one child or didn’t give birth after IVF.
The researchers said that hormones produced by the multiple births might have something to do with this increased risk. And the mothers themselves may also have traits that increased their breast cancer risks.
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Els Groeneveld, MD, from the VU University Medical Centre of Amsterdam, the Netherlands, led this study that looked at data from the Omega study, which involved 19,861 women who received assisted conception services between 1983 and 1995.
IVF is one type of assisted conception. In this procedure, a woman's eggs are fertilized outside of her body. Her eggs are then transferred to her uterus with the hope that they will implant and result in a pregnancy.
For this study, a total of 12,589 women completed questionnaires about the outcomes of the fertility treatments they received.
Of this group, 317 women developed breast cancer. After adjusting for a number of factors such as number of IVF cycles and year of treatment, the researchers found that women who had multiple births had a 44 percent higher breast cancer risk than did women who had one baby or women who did not give birth.
One finding of note was that the risks were higher only in women whose multiple births occurred following complete embryo transplantations. Multiple pregnancies conceived after incomplete implantations were not at increased risk.
This finding suggests that the pregnancies themselves are not the sole reason for increased cancer risks. Rather, the mothers could have had traits that increased their risks, including higher levels of a protein called vascular endothelial growth factor (VEGF).
VEGF is involved in the development and progression of breast cancer. The protein also assists in the successful implanting of embryos, Dr. Groeneveld’s team has recently discovered.
"So the main message of our study is that the increased breast cancer risk is not only a consequence of the multiple pregnancy itself because of high hormone levels, but that the risk of breast cancer may already be elevated prior to conception in women who have the potential — the 'maternal trait' — to develop a multiple pregnancy from all transferred embryos, " Dr. Groeneveld said in a press release.
Findings from this study were presented July 9 at the annual meeting of ESHRE (European Society of Human Reproduction and Embryology).
All research is considered preliminary before it is published in a peer-reviewed journal.
