There is no difference in the likelihood of deformity between a child conceived naturally and one conceived through in vitro fertilization, medical researchers said Wednesday.

The incidence of children with congenital anomalies, including pervasive development disorder, stood at 2.7 percent for those born through in vitro fertilization, according to a survey by the Japan Society of Fertilization and Implantation. The survey covered 817 children aged 5 who had been born through in vitro fertilization in 1997.

The rate for newborns from natural pregnancies came to 1.8 percent, according to research in 2002, but the researchers said the discrepancy is negligible, considering that it is easier to detect congenital anomalies in 5-year-old children than in new-born infants.

The researchers also said they found no differences in physical and mental development between the two groups.

"Our research shows children (born) from in vitro fertilization do not have any problems as a whole, but we need to continue monitoring them until they reach reproductive age," said Yukio Nakamura, professor emeritus at Kyorin University and head of the society.