Risk of IVF babies being born with cerebral palsy halves due to decline in twins, study reveals

The risk of IVF babies being born with cerebral palsy has fallen by 50 per cent due to the decline in twins, a study has found.

Fewer twins are being conceived using the method because doctors are reducing the practice of implanting multiple embryos into the woman's womb, according to scientists at Copenhagen University Hospital in Denmark.

Women who have just one embryo transferred during IVF treatment are five times more likely to give birth to a healthy baby as there is less risk the child will be born low-weight or delivered prematurely, researchers from the University of Aberdeen previously found.

IVF twin rates have declined from almost 25 per cent in the 1990s to less than 5 per cent today.

This latest study now indicates that the number of babies being born with cerebral palsy, a condition which affects movement and coordination, has more than halved in the past 20 years and the risk is now equal to those conceived naturally.

Using data from Denmark, Finland and Sweden, the researchers examined some 112,000 IVF children born over 24 years.

They found that the prevalence of cerebral palsy among single babies born from IVF decreased from 8.5 per 1,000 to the normal population rate of 2.8. For twins, the rate remained stable at 10.9.

Dr Anne Lærke Spangmose presented the findings at the online Annual Meeting of the European Society of Human Reproduction and Embryology.

"The inclusion of complete IVF and naturally conceived birth cohorts makes our data robust and has allowed assessment of the true risk of cerebral palsy in IVF and its decline over time," she said.

"Multiple embryo transfer is still standard care in many countries. Our findings emphasise that single embryo transfer and singleton births should be encouraged worldwide."

Large registry studies have shown that the risk of cerebral palsy has virtually disappeared in IVF children born in the Nordic countries after a policy of single embryo transfer was introduced in the early 2000s.

The NHS recommends that women aged 39 and under should have a single embryo transfer where possible, while women aged 40 and above can have a double embryo transfer.