Our objective was to evaluate long-term outcome of children born after inadvertent administration of a gonadotrophin-releasing hormone agonist (GnRHa) in early pregnancy, compared to a control group of children born to matched women undergoing in-vitro fertilization and children born after spontaneous pregnancies. Six children from six pregnancies, exposed to a long-acting gonadotrophin agonist, comprised the study group and 20 children were included in the control groups. Pre-, peri- and post-natal data were collected and the children were followed and examined at a mean age of 7.8 ± 2.0 years. All children underwent physical and neurological examination, and psychological tests. In the study group, one child was born with a major congenital malformation (cleft palate), and four children subsequently demonstrated neurodevelopmental abnormalities, including epileptic disorder (n = 1), attention deficit hyperactivity disorder (n = 3), motor difficulties (n = 3) and speech difficulties (n = 1). In the control groups, one child had attention deficit hyperactivity disorder. This observation of neurodevelopmental abnormalities in four of six children in the study group justifies the need for long-term follow-up of more children previously exposed to gonadotrophin-releasing hormone agonist.