Children born to women who took fertility drugs are more than twice as likely to develop leukemia, French scientists announced Tuesday.
Researchers from the Center for Research in Epidemiology and Population Health (INSERM), based in a southern suburb of Paris, linked the use of ovarian-stimulating drugs to a 2.6-fold increase in acute lymphoblastic leukemia (ALL), the most common type.
The risk of developing the rarer acute myeloid leukemia was increased 2.3-fold by the drugs, according to research presented at the Childhood Cancer 2012 conference in London.
Children whose mothers struggled to conceive for more than a year were 50 percent more likely to develop ALL, the study found.
The research, which looked at the mothers of 764 French children diagnosed with acute leukemia and 1,681 without the disease, did not find an increased risk with in vitro fertilization (IVF) or artificial insemination.
Study leader Dr. Jeremie Rudant said, "It has always been hypothesized that assisted reproductive technologies may be involved in the onset of childhood cancer as they involve repeated treatment at the time of conception and/or manipulation of the sperm and egg. And it is now established that a majority of acute leukemia have a prenatal origin."
He added, "Previous studies have suggested a link between infertility treatments and acute childhood leukemia, but there haven't been many studies. Most of them have been small, and they focused either on IVF or hormonal treatment. Our study was much larger, and it's the first time that a specific increased risk linked to fertility drugs has been found."
Rudant said that the findings, which were not yet published in a scientific journal, "indicate that more research is now needed to investigate more closely the link between specific types of fertility drugs and what role the underlying causes of infertility may play in the potential development of childhood leukemia."
Statistics indicate that infertility affects one in six couples worldwide, with an estimated 250,000 babies born every year as a result of fertility drugs.
However, in Britain, where about 44,000 cycles of fertility treatment are carried out each year, there are just 400 cases of childhood leukemia each year.