Frozen Embryo Transfer In IVF May Lead To Healthier Babies

12.01.2012

VF babies born from frozen embryos are heavier and result in longer pregnancies than those born from fresh embryos, research suggests.

Freezing embryos enables couples to have several cycles of IVF with eggs collected during one round of treatment. By putting some on ice, couples can use up their fresh embryos before moving on to frozen ones at a later date.

Today’s research suggests frozen embryo transfer in IVF may lead to healthier babies, owing to a good birth weight and ability for the foetus to last the course of pregnancy without being premature.

Presented at the British Fertility Society Annual Meeting in Leeds, the study involved measuring the weight and length of gestation for 384 babies born after fresh embryo transfer and 108 born after frozen embryo transfer.

All the babies were single births, with no twin or triplet pregnancies included in the study.

Babies born from frozen embryos were, on average, 253g heavier than those born from fresh, the results showed.

The proportion of low birth weight babies (weighing less than 2.5kg) was also lower in this group (3.7per cent compared to 10.7 per cent for babies born from fresh embryos).

Frozen embryo babies typically had a longer gestation period (0.65 weeks longer) than those born from fresh embryos, the research also found.

Lead researcher, Suzanne Cawood, deputy head of embryology at the Centre for Reproductive and Genetic Health, London, said: 'For all assisted reproduction technologies, it is important that we ensure the procedures promote optimal health in the resulting children throughout their lives.

'Our study suggests that babies born from frozen embryos have a significantly longer gestation period and are significantly heavier at birth compared to babies from fresh embryos.

'This is important because prematurity and low birth weight are both risk factors for poorer health later in life and are linked to higher rates of behavioural and learning difficulties.

'This means that resulting babies may potentially be healthier if frozen embryos are transferred rather than fresh embryos.

'The reasons behind these findings are not yet fully understood, but one possibility may be that there is a difference in the uterine environment between fresh cycles, when embryos are transferred soon after the eggs have been collected, compared to frozen cycles when the uterus has not been stimulated in the days before transfer.

'However, further research is needed to test this hypothesis.'

In 2008, Danish scientists also found that babies born after frozen embryo transfer had higher birth weights than those born from fresh embryos.

They suggested only top quality embryos survive the freezing and thawing process.

dailymail.co.uk