The average birth weight of babies conceived by IVF has increased by approximately 180 grams over a 25-year period, a UK study suggests.
Researchers at the University of Manchester analysed data from almost 3000 singleton babies born through IVF and ICSI at St Mary's Hospital in Manchester, from 1991 to 2015.
Previous studies suggest that the risk of low birth weight is increased for babies conceived via IVF compared with non-IVF babies. Low birth weight is also a risk factor for the development of chronic diseases in adulthood.
'Our research further suggests that the newest generation of IVF children may be at lower risk,' said Professor Daniel Brison at the University of Manchester, who led the study. 'But we do feel it is important to continue to monitor the health of all IVF children and alter IVF practices to make the treatments as safe as possible.'
The results were published in the journal Human Reproduction. The researchers wrote of the progressive increase in birth weight: 'Such a change is not seen in the general population of live born singletons in the UK or other developed countries, and seems to be specific to this IVF population.'
The team also reported that the birth weight of babies conceived by IVF from frozen and then thawed embryos was higher than those conceived via fresh embryo transfer. The difference in birth weight following the transfer of fresh or thawed embryos remains unclear and further research needs to be done to investigate these differences, said the team.
The researchers hypothesised that the increase in birth weight is due to the development of reproductive medicine over time.