Children born after intensive IVF treatment may have a greater risk of developing heart disease

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New evidence emerged that this method doubles the risk of premature birth.

Children born following intensive IVF treatment may have a greater risk of developing heart disease than those conceived naturally, scientists will say this week.

Fertility experts claim there is growing evidence that treatment in which high doses of powerful drugs are used to stimulate egg production can result in offspring with higher blood pressure and stiffer, thicker arteries than normal. That could raise their risk of heart attacks and strokes as adults, said the Daily Mail.

This 'high stimulation' approach is commonly used by fertility clinics and many of Britain's 66,000 IVF children are thought to have been born as a result of it.

However, new evidence is also emerging that this method doubles the risk of premature birth and raises the odds of low birthweight, compared to natural conception.

The findings matter because babies who are premature or small have a greater chance of developing long-term health problems, including heart disease and type 2 diabetes.

The issues will be discussed this week at the annual conference of the International Society for Milder Approaches to Assisted Reproduction (ISMAAR) in London.

Last night, ISMAAR president Professor Geeta Nargund urged fertility clinics to take note, saying they had a responsibility to create healthy children.

Debate is raging about how much these problems result from parental infertility, and how much they are due to fertility treatment. But evidence is building that the harsh regimes many women endure to have a baby are partially to blame.

These involve women being given high doses of follicle stimulating hormone (FSH) to spur their ovaries to release lots of eggs together rather than just one.

Studies show this often leads to poor quality eggs and wombs compromised by excessive levels of the hormone oestrogen, said Prof Nargund. That in turn could affect the long-term health of the child.

Among the studies being highlighted is a Swiss project comparing heart and blood vessel health in 65 pre-school children born from fertility treatment, with 57 conceived naturally. It found those born via fertility treatment had "generalised vascular dysfunction" – including stiffer blood vessels and thickening of the carotid arteries that supply blood to the head and neck.

Professor Anja Pinborg of Copenhagen University said it was far too early to say these children would actually suffer more heart disease in adulthood. "Whether it's true or not – it's still debatable," said Prof Pinborg, who will be presenting at ISMAAR.

Another study being presented, looking at all UK fertility treatment births, will show slightly poorer health outcomes in children where more than 18 eggs were retrieved in one go.

US IVF pioneer Dr Sherman Silber will present results showing that, while more than 20 eggs from highly stimulated ovaries are needed on average to end up with a baby, only four eggs are needed from unstimulated ovaries.

Dr Silber told The Mail on Sunday: "Hyper-stimulation is crazy, because you end up getting a lot of poor-quality eggs."