There is increased concern that the transfer of more then one embryo is unnecessary and could expose a child to more risk.

Research is now indicating that transferring one embryo, rather then tow or three, results in the same chance of a successful pregnancy. Fertility experts in France examined 25,000 pregnancies that had fertility treatments between 1986 and 1998. Their research found that 9/10 triplets born were premature compares to 8% of singleton pregnancies. From these pregnancies 5% of them were born before 33 weeks of pregnancy. From this number 28% of premature babies were triplets, only 2% of this number was born from singleton pregnancies. In 1999 of the 23,254 cycles of IVF treatment performed in the UK, only 3.2% of pregnancies were from single embryo transfer.