People conceived through in vitro fertilisation treatment should be monitored for the early onset of high blood pressure, diabetes and certain cancers before the age of 50, according to a fertility specialist.
While IVF is generally considered to produce healthy babies, doctors have identified subtle genetic changes that may raise the risk of particular medical conditions in later life.
Since the birth of the first test tube baby, Louise Brown, on 25 July 1978, more than three million babies have been born through fertility treatment around the world. The vast majority are still under the age of 30.
The extent to which IVF babies develop more hypertension, diabetes and cancer will begin to emerge over the next two decades as they enter middle age, doctors said.
“By and large these children are just fine, it’s not like they have extra arms or extra heads, but they have a small risk of undesirable outcomes. What’s going to happen to them down the line? Bear in mind none is older than 31-years-old,” said Carmen Sapienza, professor of pathology at Temple University School of Medicine in Philadelphia.
Higher risk
“They have a much higher frequency of being low birthweight and this results in a higher tendency to be obese, a higher risk of type 2 diabetes and hypertension when you reach 50 years old,” Sapienza told the annual meeting of the American Association for the Advancement of Science in San Diego on Monday.
In 2006, the Department of Health warned that Britain was facing a new wave of cancer on the back of increasing obesity in the population.
Obesity plays a role in 4% of cancers, including breast and womb cancer, and has also been linked to the disease in the bowel and kidney. In most cases, hormones released from fat are to blame.
“It makes sense for IVF children to watch out for hypertension, obesity and related diabetes and cancers as they reach their fifties,” Sapienza said. “It will be interesting to monitor these children.”
Altered genes?
Unlike naturally conceived babies, those who are created through IVF spend their first three days after conception in a Petri dish and are exposed to more oxygen than is available in the womb. The altered oxygen levels and the culture media used to keep embryos alive are thought to alter how genes are expressed in IVF embryos.
Sapienza’s team analysed levels of gene expression in 75 children born through IVF and compared this with 100 naturally born babies. They found differences in 6% to 10% of the genes studied.
Some of the genes that differed are known to play a role in normal development and growth, while others are linked to metabolism and the formation of fat in the body.
The findings come as the inventor of one of the most common fertility treatments in use in Britain warned that the technique, in which sperm are injected directly into eggs, is being overused, exposing patients to needless risk and expense.
Dr Andre van Steirteghem at the Brussels University Centre for Reproductive Medicine co-invented intracytoplasmic sperm injection or ICSI in the 1990s, a procedure that accounted for 48% of all IVF treatment in the UK in 2007. The procedure tends to be used more in private clinics than in the NHS. The Assisted Reproduction and Gynaecology Centre in London, which has Britain’s highest success rates, uses ICSI in 78% of treatment cycles.
ICSI costs up to £2 000 more than standard IVF and carries a slightly higher risk of producing babies with birth defects. It was developed specifically to treat male infertility, but many clinics now use it for all patients, because it is more likely to lead to viable embryos.
“Several clinics use ICSI for everybody. I don’t think it’s necessary when you have a method like conventional IVF which is certainly less invasive,” said Dr van Steirteghem. “ICSI has been overused. The important thing is we have to see what will come out in the future, so long-term follow-up is important.”
In the UK, the use of ICSI as a proportion of all fertility treatment rose from 15% in 1995 to 43% in 2005. The Human Fertilisation and Embryology Authority recommends that ICSI be used only when problems have been identified with a man’s sperm, or when previous IVF treatment has failed.
Allan Pacey, senior lecturer in andrology at the University of Sheffield, said: “There is a real danger that ICSI is being overused in some parts of the world and I suspect this is out of fear of patients experiencing ‘failed fertilisation’ using conventional IVF. The problem with overusing ICSI is that there is a very small but statistically significant increased risk that some of the babies born from the technique appear to have health problems.” – guardian.co.uk