Increased incidence of coronary heart disease associated with "double burden" in a cohort of Italian women

Objective of this study was to assess the risk of coronary heart disease (CHD) associated with the combination of employment status and child care among women of working age, also examining the sex of the offspring. Only two previous studies investigated the effect of double burden on CHD, observing an increased risk among employed women with high domestic burden or providing child care, although the relative risks were marginally or not significant. The study population was composed of all women 25-50 years old at 2001 census, living in Turin in families composed only by individuals or couples, with or without children (N = 109,358). Subjects were followed up during 2002-2010 for CHD incidence and mortality through record-linkage of the cohort with the local archives of mortality and hospital admissions. CHD risk was estimated by multivariate Poisson regression models. Among employed women, CHD risk increased significantly by 29% for each child in the household (IRR = 1.29) and by 39% for each son (IRR = 1.39), whereas no association with the presence of children was found among non-employed women or among employed women with daughters. When categorized, the presence of two or more sons significantly increased CHD risk among employed women (IRR = 2.23), compared to those without children. The study found a significant increase in CHD risk associated with the presence of two or more sons in the household, but not daughters, among employed women. This is a new finding, which should be confirmed in other studies, conducted also in countries where the division of domestic duties between males and females is more balanced, such as the European Nordic countries.