Infertility treatment could be more effective in the future, as scientists working at the University of Bristol believe they have found the optimum number of embryos to implant during assisted conception.
The team studied data from the UK Human Fertilisation and Embryology Authority (HFEA) and found that the live birth rate with the transfer of two embryos is higher than when only one is implanted.
However, the correlation between number and success does not continue indefinitely.
"Transfer of three embryos did not increase the live birth rate over that seen after transfer of two embryos, but was associated with an increased risk of adverse perinatal outcomes," said the authors of the study, professor Debbie Lawlor from the University of Bristol's School of Social and Community Medicine and professor Scott Nelson from the University of Glasgow's Centre for Population and Health Sciences.
The HFEA said a multiple birth is the biggest risk to those couples who are undergoing IVF treatment.