Women who undergo in-vitro fertilization and give birth to multiple babies face higher risks for breast cancer than childless women or those who have single births, new research shows.
 

Dutch investigators who tracked nearly 20,000 women who received IVF or other fertility treatments between 1983 and 1995 found those who had twins or other multiple births were 44 percent more likely to develop breast cancer than those who had singletons.

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The researchers, who presented their findings at a meeting of the European Society of Human Reproduction and Embryology, suggested the increased risks may not result from the multiple pregnancies themselves but frpm hormonal factors and maternal traits that may cause some women to experience more pregnancies as a result of fertility treatments.
 

Lead researcher Els Groeneveld, from the VU University Medical Centre of Amsterdam, the Netherlands, said more studies are needed to determine the potential factors that may raise some women’s breast cancer risk following IVF procedures.
 

"It has been generally assumed that increased levels of estrogen and progesterone in multiple pregnancies stimulate cellular proliferation in the breast, which increases accumulation of somatic mutations during cell division and leads to the development of breast cancer," Groeneveld said.

"Thus, breast cancer could be seen as a consequence of the multiple pregnancy itself. However, we also hypothesize that an additional maternal trait might be associated with an increased breast cancer risk in these women."