Developmental plasticity and its relevance to assisted human reproduction.

The advent of assisted reproduction has allowed the conception of millions of individuals who otherwise would not have existed. Although most ART children are born healthy, there is increasing awareness of the plasticity of the human embryo causing concerns about potential long-term consequences of ART for the growth, development and health of this growing population of individuals. Evidence from studies in animals and humans suggest that physiology and metabolism may be permanently affected by ART. It suggests that ART children may be at increased risk of later cardiometabolic diseases. Part of this increased susceptibility to cardiometabolic diseases seems to be due to parental predisposition, while part of the increased susceptibility seems to be due to the ART procedure itself. Due to the fast development of new techniques in ART, it is unclear whether newer techniques are associated with similar risks. There is evidence to suggest that the newer techniques are safer, but the rapid developments in reproductive medicine and ever increasing indications for ART make it difficult to draw conclusions. Until more is known about the effectiveness and safety of ART for the broader indications in which ART is currently used, caution in using ART is mandatory.Further progress could be made if long-term follow-up studies were included in the development of new ART techniques. Harmonization of measurements in human and animal studies of ART would allow faster scientific progress and less scientific waste. Also, including more details of the ART procedures in ART registries and allowing follow up of ART children through linking registries with already collected data from perinatal registries, child health clinics and schools would help to provide a better understanding of the growth, development and health of the growing population of ART children. Ultimately, these studies will provide the much needed information on how to provide ART children with the best possible start in life.