But the reason for the findings, which were presented at the
British Fertility Society annual meeting, are not known.
The claim comes from a study in which the weight and length of gestation of 384 babies born after fresh embryo transfer and 108 born after frozen embryo transfer were measured.
The results show that babies born from frozen embryos were an average of 253g heavier than those born from fresh embryos.
The percentage of babies weighing less than 2.5kg was 3.7% for frozen embryos and 10.7% for fresh embryos.
Frozen embryo babies also had a gestation period 0.65 weeks longer, on average.
The study was carried out at the
Centre for Reproductive and Genetic Health in London and all the babies were single births.
Lead researcher Suzanne Cawood, deputy head of embryology at the centre, said the discovery means ‘resulting babies may potentially be healthier if frozen embryos are transferred rather than fresh embryos’.
She said that the reasons for the differences are ‘not yet fully understood’.
One possibility may be that there is a difference in the uterine environment between fresh cycles and frozen cycles, but the theory needs to be researched and tested, she said.
A previous Danish study also revealed that IVF babies born from frozen embryos weighed more at birth than those born from fresh embryos.
The researchers believed that this was due to weaker embryos not surviving the freezing and thawing process.
