Study suggests higher cancer rate among IVF babies

But researchers found no direct cause-and-effect with assisted reproduction technology

Children conceived using in vitro
fertilisation have a higher risk of developing cancer than children who were conceived
naturally, new research shows.

While the study found the risk of
cancer was increased by 42 per cent for Swedish youngsters conceived with IVF,
the absolute risk of cancer was still quite low.

“We found a roughly 50 per cent
increased risk for cancer in the IVF children, which means that if the risk
without IVF is two per 1,000, it increases to three per 1,000 after IVF,” explained
study author Dr. Bengt Kallen, a professor emeritus in embryology at the
Tornblad Institute at the University of Lund in Sweden.

The findings, posted online on 19
July, will be published in the August print issue of Paediatrics

In vitro fertilisation is an
assisted reproduction technology. Using eggs harvested from the prospective
mother and sperm given by the prospective father, doctors can create human
embryos that are then implanted into the mother’s uterus.

Babies born using this technology
are known to have an increased risk of birth defects and of birth
complications, such as pre-term birth. Previous research has also suggested
that children born through this method of conception may also have an increased
risk of cancer.

Using the Swedish Medical Birth
Register, the researchers gathered information on almost 27,000 children who
were born using IVF in Sweden from 1982-2005.

When they looked at the number of
children who had cancer, they found that 53 born from IVF had developed cancer
compared to the expected rate of 38 cases of cancer in non-IVF children.

Other factors appeared to influence
the risk of cancer as well. Children born before 37 weeks’ gestation and those
with a low birth weight, respiratory problems or a low Apgar score (a test
given at birth to assess a newborn’s health), had higher rates of cancer.

A mother’s age, weight, smoking
status and the number of miscarriages she’d already had did not appear to
affect a child’s cancer risk, nor did a multiple birth pregnancy.

Cancers of the blood, such as acute
lymphoblastic leukaemia, were the most common, affecting 18 children. The next
most common were cancers of the eye or central nervous system, affecting 17 children.

Although it is not clear what is to
blame for the increase, the study authors think it is unlikely that IVF is at
the root of the increased risk of cancer.

“This study is interesting and
thought-provoking, and it adds to our growing knowledge of potential IVF
consequences,” said Dr. David Cohen, chief of reproductive medicine at the
University of Chicago. “But, it’s difficult to think what the biological plausibility
would be.”