Minor congenital anomalies, major congenital malformations and development in children conceived from cryopreserved embryos.

A total of 91 children (68 singletons, 20 twins and three triplets) who were conceived from cryopreserved embryos between 27 December 1989 and 18 January 1994, and 83 normally conceived control children (81 singletons and two twins) of a similar age, sex and social class, were assessed for minor congenital anomalies and major congenital malformations. Their development was assessed using the Griffiths Scales of Mental Development. The incidence of minor congenital anomalies (31.9% in the cryopreserved embryo group and 21.7% in the controls) and major congenital malformations (3.3 and 2.4% respectively) in our two groups of children was statistically similar. The relative risk (odds ratio and 95% confidence interval) in the cryopreserved embryo group compared with the controls was 1.7 (0.8, 3.3) for minor congenital anomalies and 1.4 (0.2, 8.5) for major congenital malformations. The minor congenital anomalies were mostly naevi and haemangiomas. The major congenital malformations included Down's syndrome, Beckwith-Wiedemann syndrome and hypophosphataemic rickets in the cryopreserved embryo group and hydronephrosis and gastroschisis in the controls. The Griffiths assessment showed that children from the cryopreserved embryo group and the controls were functioning at a similar level. The mean Griffiths quotient and subquotient values were greater than the standard 100 in children with or without congenital abnormalities. These results in the cryopreserved embryo group are reassuring in that the minor congenital anomaly and major congenital malformation rates were similar to those in normally conceived children of a similar age, sex and social class and their development was not adversely affected by cryopreservation.