Birth characteristics and perinatal outcome of babies conceived from cryopreserved embryos.

The objective of this retrospective study was to compare the birth characteristics and perinatal mortality of babies conceived from the use of cryopreserved embryos with those resulting from in-vitro fertilization (IVF) and fresh embryo transfer. A total of 232 consecutive births, one pregnancy termination and a total of 283 babies in the cryopreserved group were studied. The IVF data included 763 births, three terminations and 961 babies, based on a previous analysis. There was no difference in the incidence of twin (18 versus 19%) and triplet births (2 versus 3%) in the cryopreserved and IVF groups respectively. The mean gestational age and birthweight of singleton, twin and triplet births were not significantly different between the groups. No difference was found in the perinatal mortality rates. The incidence of major congenital malformations in the cryopreserved group (1%) was significantly lower than that in the IVF group (3%; P < 0.05). It is concluded that the birth characteristics of babies conceived from cryopreserved/thawed embryos are similar to those from fresh embryos. There are fewer congenital malformations in the cryopreserved group.