A prospective comparative study was carried out on the development of 40 infants born by in-vitro fertilisation (IVF) and of their relationships with their mothers. This group was compared with two control groups: Children born to infertile women after ovulation had been induced but where assisted reproduction was not used. A group of infants born after normal conception without medical intervention at all. The preliminary results at 9 months showed that there were no major developmental problems in IVF infants as compared with the controls. All the same, there are more troubles as far as sleep is concerned with IVF children and with the group of infertile mothers and these symptoms seem to be linked to difficulty in the mother-infant relationship. These troubles are minor ones and appear to be only temporary as far as can be told after 18 months.