Obstetric and perinatal outcome of children conceived from cryopreserved embryos.

The main purpose of this study was to evaluate the obstetric and neonatal outcome of children conceived from cryopreserved embryos. The medical records of 270 infants (163 singletons, 98 twins and nine triplets) were reviewed and compared with two control populations of children born after in-vitro fertilization (IVF) with fresh embryos and children born after spontaneous pregnancies. The controls were matched according to maternal age, parity, plurality and date of delivery. In the cryopreserved group the gestational age at delivery for singletons was 279 +/- 13 days with birthweight 3476 +/- 616 g; for twins gestational age was 257 +/- 19 days with birthweight 2574 +/- 560 g; for triplets gestational age was 228 +/- 3 days with birthweight 1752 +/- 183 g. The incidence of preterm birth (< 37 weeks gestation) was 5.6% for singletons, 44.9% for twins and 100% for triplets. Seven children had major malformations (2.7%) and perinatal mortality occurred in two children (8/1000). Gestational age at delivery, birthweight, the incidence of malformations and the perinatal mortality were comparable with the two control groups both for singletons and twins. Significantly more singletons in the cryopreserved group were delivered by Caesarean section compared with the spontaneous group. The number of infants with low Apgar score (< 7 at 5 min) and the number of infants admitted to neonatal intensive care units were similar in the cryopreserved and spontaneous groups. In conclusion, the cryopreservation process did not seem to adversely influence fetal development and no increased perinatal risk was found.