Are major defects in children conceived in vitro due to innate problems in patients or to induced genetic damage?

Birth anomalies recently detected in epidemiological studies indicate greater risks following assisted human reproduction than with natural conception. Some of these conclusions and assumptions are questioned in this paper, and the effects of specific causative factors unique to some infertile couples are analysed. Other recent studies have identified imprinting defects as causes of birth disorders following IVF or intracytoplasmic sperm injection. While few in numbers, they apparently involve unusual factors in conception such as aberrant responses among preimplantation embryos to culture medium or serum. Various genetic and developmental factors in infertile couples influencing the origin of such birth outcomes are assessed, and the significance of imprinting and its embryological roles are discussed.