Published in 2003, a case-control study of roughly 400 individuals in Sweden identified an association between high birth weight and RA. To see if this association played out in a larger population, the researchers turned to a study of 87,077 women in the Nurses’ Health Study.
In 1976, nurses were invited to participate in this study that involved a baseline survey and then a biennial questionnaire regarding health status, lifestyle, family medical history and health practices.
The investigators of the recent study excluded women who had cancer or any type of connective tissue disease at baseline or follow-up because these can cause symptoms that can be confused with RA. Also excluded were women who reported having RA or connective tissue disease during follow-up, but in whom the diagnosis could not be confirmed by review of their medical record.
The study population included only women who answered a 1992 survey that collected information about birth weight. After these exclusions, 87,077 individuals were included in the study and 619 of them developed RA. Through statistical analysis, the investigators discovered that a birth weight of greater than 4.54 kilogram doubled the risk that a person would develop RA as an adult compared with individuals who had an average birth weight.
“In utero, the fetus will react appropriately to different stressors. However, this may preprogram the fetus so that when it gets out into the world, this preprogramming is not helpful out in the ‘real world’,” said Lisa Mandl, Medical Doctor at Hospital for Special Surgery.
In other words, the fetal environment may be preprogramming people’s brains or endocrine systems to be maladapted in later life. Mandl says that patients with RA are known to have a dysregulated hypothalamic-pituitary-adrenal (HPA) axis, and this axis may be affected in utero.
MEDICA.de; Source: Hospital for Special Surgery