Risk of anomalies, low birth weight, and multiple pregnancies may be increased

Parents who conceive after fertility treatments would like to know if their children are at excess health risks compared with children who have been conceived naturally. They would like studies to be done to monitor outcome—but not necessarily on their own children.

Outcome studies of in vitro fertilisation are relatively few to date and hampered by difficulties such as high cost, ethical considerations, recruitment of appropriate controls, and unwillingness of some parents even to tell their children how they were conceived, let alone bring them for assessments. Early studies were small, uncontrolled, and had other methodological errors. In contrast the pace of advances in the treatment of infertility has been rapid. The development of embryo cryopreservation has been followed by potentially more hazardous techniques such as intracytoplasmic sperm injection and extended embryo culture. Other techniques entail manipulating the embryo in vitro by assisted hatching and preimplantation genetic diagnosis, a diagnostic procedure.

The eldest individuals born after in vitro fertilisation are now young adults, and 1% of children in developed countries are now conceived through …