Is being first-born another risk factor for metabolic and cardiovascular diseases?

Future Cardiol. (2013) 9(4), 447–450 Birth rates have been steadily declining throughout the world, particularly in Europe and many Asian countries [1]. This reduction in birth rates is a result of a number of factors, including govern ment policies (e.g. one-child policy in mainland China), greater family planning, personal choice and economic constraints [2]. As a result, there has been a large increase in the number of one-child families and, consequently, a considerable increase in the proportion of first-born children within many populations [2]. Thus, any adverse health outcomes that are associated with being first-born (primogeniture) would likely affect an ever-increasing proportion of the world’s population. Notably, only recently has evidence emerged on the consequences of primogeniture on long-term metabolic and cardiovascular health risks.