This systematic review has found that single pregnancies after transfer of frozen thawed embryos were associated with a lower risk of perinatal mortality, small for gestational age babies, preterm birth (defined as before 37 weeks’ gestation), low birth weight (defined as less than 2,500g) and antepartum haemorrhage (bleeding during pregnancy). However, the risk of caesarean section was increased. The absolute risk differences seen were small in all cases. The results of this study should provide reassurance to people who have had their embryos frozen, and to cryopreservation programmes.
Source: NHS Choices