Freezing IVF embryos ‘doesn’t boost chances of becoming pregnant’

FREEZING embryos after IVF does not raise the chances of getting pregnant, research has revealed.

Women undergoing fertility treatment usually have a fresh embryo transferred into the uterus within a week of eggs being retrieved, with any ‘ spare’ embryos frozen for use at a later date.

But, in recent years, some clinics have switched to a ‘freeze-all’ strategy, believing it gives women’s bodies more time to recover from the disruptive hormonal treatment.

However, research has found there is no benefit to using frozen embryos over fresh ones, with pregnancy rates about the same.

The study said IVF clinics should avoid ‘freeze-all’ strategies and fresh transfers should remain the ‘gold standard’. Figures from the Human Fertilisation and Embryology Authority show frozen embryos are now used in a third of IVF cycles in the UK, and their use has almost doubled in five years.

Some of this increase is because freezing the embryos allows women to delay pregnancy until a date of their choosing.

But it also reflects suggestions from scientists that freezing all embryos would improve success rates as women have more time to recover from IVF medication and invasive egg collection procedures.

A trial involving 460 women aged between 18 and 39 in Denmark, Sweden and Spain, set out to establish if there are benefits to this approach.

Half of the women underwent treatment with fresh embryos, while the other half used frozen ones that were thawed out at least a month later before being transferred into the womb. Scientists

‘Body has time to recover’

found 27.8 per cent of those who froze their embryos became pregnant, compared with 29.6 per cent who had a fresh transfer.

And no significant difference was found in the live birth rates between the two different groups of women.

The study’s authors, led by researchers from Hvidovre Hospital in Copenhagen, Denmark, told the British Medical Journal: ‘The findings warrant caution in the indiscriminate application of a freeze-all strategy when no apparent risk of ovarian hyperstimulation syndrome is present.’

Ovarian hyperstimulation is a rare complication of IVF when too many eggs develop in the ovaries, which become very large and painful.