IVF babies born from frozen embryos are healthier than those from fresh ones
Reunited at birth: Twins Ruben (right) and Floren were born five years apart. They both come from the same batch of embryos, but Floren’s embryo was kept on ice for half a decade
IVF 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.
Embryos being prepared for freezing: The preservation enables couples to have several cycles of IVF with eggs collected during one round of treatment
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.
A tube containing preserved embryos: Babies born from frozen embryos were, on average, 253g heavier than those born from fresh – and resulted in longer pregnancies
‘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.
Infertility Network UK chief executive, Clare Lewis-Jones, said the new study supported the move to transferring only one embryo at a time.
This cuts down the multiple pregnancy rate – which is higher in IVF than natural conception – with health benefits for mother and baby.
She said: ‘These initial findings, if proved accurate following further research, will give the medical profession more evidence to encourage patients to accept single embryo transfer, which reduces the risks of multiple births to both mother and babies.
‘Single embryo transfer gives the best
possible outcome – a healthy singleton baby – with the chance of further
frozen embryo transfers in the future.
‘If these results prove positive, then we would welcome this and hope it benefits infertile couples everywhere.’
But she said many primary care trusts (PCTs) in England ignore guidelines saying women are eligible for up to three free cycles of IVF on the NHS.
Many also only provide funding for fresh embryo transfers and are ‘not funding subsequent frozen embryo transfers which forces patients into the private sector’.
‘We find this totally unacceptable and call upon all PCTs once and for all to fund full cycles of IVF treatment as recommended by the National Institute for Health and Clinical Excellence (Nice),’ she said.
A second study presented at the meeting suggests surrogacy does not have a negative impact on the surrogate’s own children.
‘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’
The study is said to be the first in the
world to examine the psychological health of children whose mothers have
Experts at the Centre for Family Research at the University of Cambridge interviewed 16 children aged 12 to 22 (seven boys and nine girls) about their experiences.
All of the children interviewed had a positive view of their mother’s involvement in surrogacy.
The majority (10) were in contact with the surrogacy child and reported a good relationship with him or her.
Most (12) said they openly discussed surrogacy with their friends, and often received a positive reaction.
Most of the children also scored within the normal range for self-esteem.
Researcher Susan Imrie said: ‘The results we present here are only preliminary findings and form part of a larger ongoing study into the experiences and psychological health of surrogate mothers and their families.
‘There have been concerns raised in the past about the effect of surrogacy on a surrogate’s own children. Our initial results indicate that the children of mothers who have carried a surrogate baby for another couple do not face negative consequences as a result of this.
‘So far, all children interviewed have a positive view of surrogacy and their mother’s involvement.’