FERTILITY drugs can more than double the chances of children born to mothers who struggle to get pregnant developing leukaemia, a study has shown.
Children were 2.6 times more likely to become ill with acute lymphoblastic leukaemia (ALL), the most common type of childhood leukaemia, if their mothers had been treated with ovary-stimulating drugs.
They had a 2.3-fold increased risk of suffering the rarer form of the disease, acute myeloid leukaemia.
Children conceived naturally after their mothers tried for more than a year to get pregnant had a 50pc greater-than-normal likelihood of developing ALL.
But no heightened risk of childhood leukaemia was associated either with in-vitro fertilisation or artificial insemination.
The French scientists cannot yet fully explain their findings, the first to show a specific link between the use of fertility drugs and childhood leukaemia.
Study leader Dr Jeremie Rudant, from the Centre for Research in Epidemiology and Population Health in Paris, said: "The findings 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 leukaemia."
Dr Rudant presented the results at the Childhood Cancer 2012 conference in London, hosted by the charity Children With Cancer UK. A total of 2,445 French children and their mothers took part in the study.
The research comprised 764 children who had been diagnosed with leukaemia and 1,681 who were free of the disease. Mothers were asked if they had taken more than a year to conceive a child, and questioned about the treatments they had received.
Use of fertility technology is increasing worldwide. But the actual number of children developing leukaemia after their mothers undergo fertility treatment remains very small despite a significant increase in risk.
ALL can affect children of any age but is most common between the ages of one and four. It is also more likely to affect boys than girls.