French scientists said on Sunday that babies born to couples who had fertility treatment have a greater risk of birth abnormalities, and doctors should be more prepared to warn potential parents about these risks.

Geraldine Viot, a clinical geneticist, told Reuters that couples considering assisted reproductive technology (ART) treatment should be told that the risk of defects is around twice that of babies conceived naturally.

ART includes various methods like vitro fertilization (IVF) and a technique known as ICSI, in which sperm is injected directly into an egg in a laboratory.

“We found a major congenital malformation in 4.24 percent of the (ART) children,” Viot, of the Maternity Port Royal Hospital in Paris, told Reuters.  Her findings were presented to a conference of the European Society of Human Genetics in Stockholm.

She said this was about double the rate seen in the general population.  However, she also said that she thought most doctors working in fertility clinics in France only told couples about these types of risks if they asked specific questions.

“Given that our study is the largest to date, we think that our data are …likely to be statistically representative of the true picture,” Viot said in a commentary on her research.

A 2009 study found that the number of babies born worldwide through ART rose to 246,000 annually in 2002 from 219,000 in 2000.

Viot’s team studied 33 French fertility clinics and data from all ART births from these clinics from 2003 to 2007.

The parents and the pediatrician completed questionnaires, and the prevalence of birth abnormalities was compared with data from national registers.

The scientists found a five times higher rate of angioma among minor defects.  These occurred twice as frequently in girls than in boys.

The average age of the parents of babies with abnormalities did not differ statistically from other parents who had had fertility treatment.

According to Viot, the higher rate was in part due to more heart problems in ART babies, and also because of more abnormalities of the urinary and reproductive systems, particularly in boys.

Viot told Reuters that about 200,000 children in France have been born through ART so far.  This meant a birth abnormality rate of this size should be seen as “a public health issue.”

“It is important that all doctors and also politicians are informed about this,” she said.

“We also need to follow up all children born after ART and to put much more effort into trying to understand which of the procedures involved is implicated in this problem.”