The role of children and their socioeconomic resources for the risk of hospitalisation and mortality – a nationwide register-based study of the total Swedish population over the age 70

It is well-established that childless individuals and parents with many children experience higher mortality than those with few children [1–5], but mechanisms behind this finding are less clear. Both biological [3, 6, 7] and social mechanisms have been proposed to explain the associations between parity and mortality [4]. Social mechanisms refer to social influence on health behaviours as well as different kinds of support that adult children can provide, potentially affecting the health and survival chances of their parents. The support that adult children can provide to their ageing parents can be both emotional, informational, and instrumental and has been hypothesised to be particularly important in old age when health starts to deteriorate [4]. Older childless individuals may thus face support deficits when in poor health and living alone and/or lacking family support [8, 9].

In studies of parity and survival, health related selection is often argued to explain part (or all) of the survival advantage of parents over non parents [3, 6, 7]. That is, parents are in general healthier than non-parents, and parents of two children are often healthier and more highly educated than parents of many children. However, the absolute difference in mortality between parents and childless individuals has shown to increase with age [10], and to be largest in ages above 90 years. If health selection was to explain all of the differences in health between parents and non-parents, we would not expect the differences to grow larger in ages well beyond average life expectancy when selection generally has played out its role. Previous research has also shown that adult children often become care-givers for their aging parents [11].

It is yet unclear when during the process of health deterioration the advantage of parents over non-parents arises, if support form adult children matters for their parents risk of developing diseases, for the chance of surviving them, or both. Previous studies examining the role of children for parental health have not systematically distinguished onset of ill health from survival after ill health has begun. Separating this is important in order to understand the advantage of parents over non-parents, and may to some extent help to disentangle the two proposed mechanisms, selection and support. For example, while health selection into parenthood or parity may play a role for differences in the occurrence of disease or overall mortality, it is less likely that selection explains disparities in survival once a disease has occurred. Instead, it can be hypothesised that structural support has a larger impact for the prognosis once a disease has manifested. Without arguing for one of these mechanisms (selection vs. support) before the other, this paper aims to describe differences in health at different stages between childless and parents.

In addition to the mere presence of children, studies have suggested that the socioeconomic resources of children are inversely related to their parent’s mortality, independent of parents’ own socioeconomic resources [12–18]. Even though the causal directions are hard to disentangle (since socioeconomic disadvantage or compromised health of parents might negatively affect educational attainment among offspring), there is some evidence for a causal benefit at least of daughters’ education on their fathers’ mortality [19]. Further, a previous study has shown that a higher education level among children is positively associated with mothers’ survival after a breast cancer diagnosis [20]. One explanation could be greater health knowledge among highly educated children, who are better placed to communicate about health behaviours, help their parents to navigate complex healthcare systems, with compliance to medication or rehabilitation programs, or seek the best available care for an ill parent [12, 14, 21]. Less is known about the association between children’s financial resources and parental health, but two previous studies found children’s education to be more closely related to mortality in old age than their income [22, 23].

In this study we aim to examine how the number of children as well as children’s socioeconomic resources are associated with their parents’ risk of hospitalisation (which may be seen as a proxy for onset of ill health), risk of re-admission (i.e. prognosis/recurrence of disease), and mortality after hospitalisation (i.e. survival after ill health has begun) as well as overall mortality in older adults.

In this nationwide population-based cohort study we show that the association between parity and health in old age differs for different health outcomes, that is, between the risk of first hospitalisation and the risk of re-admission and mortality. While it is known that childless old people have higher mortality, this study indicates that this may result from a shorter survival once a disease has occurred. If hospitalisation is a proxy for disease onset, our results further suggest that childless individuals do not necessarily face an earlier disease onset. In addition, this study demonstrates that adult children’s educational level is important for both hospitalisation as well as survival, in fact more so than the number of children itself. Finally, our results indicate that offspring’s socioeconomic resources explain part of the curvilinear relationship between parity and later life mortality observed in this and in previous studies.

The finding that childless individuals have a higher mortality than parents is in line with previous studies [4]. Only among the small group of parents with five or more children (less than 3% of the study population), we found no reduced mortality compared to childless. A complex interplay of selection processes and biological and social effects of parity may result in an ‘optimal’ number of children for parental mortality [4]. To our knowledge, parity in relation to risk of hospitalisation, re-admission and mortality after hospitalisation has not previously been studied. As such, we cannot draw comparisons with previous work. It has been hypothesised that having children may promote healthier behaviours in parents [26], which may contribute to a delay in onset of disease. Our results do not support this hypothesis since the hospitalisation risk was not lower for parents than for childless individuals. It should be noted, however, that hospitalisations are not an ideal measure of disease onset and that the probability of hospitalisation may differ between parents and childless individuals regardless of disease status.

Having three or more children was associated with a greater risk of hospitalisation than having one child. This could be related to the balance between the positive effects of having children and selection processes defining the social background and composition of this group of parents [4] which results in a greater risk of hospitalisation but lower mortality. Alternatively, children could assist their parents with seeking inpatient care for existing health problems or with transport to the hospital.

Health selection into parenthood could be an explanation for differences in morbidity and mortality between parents and childless individuals, but is less likely that selection explains disparities in survival once a disease has occurred. The observed associations between having children and re-admission or survival after hospitalisation might thus suggest support from children to matter for prognosis after disease onset. However, these findings might also stem from a difference in the probability of becoming hospitalised. Adjusting for parents’ own education and income had almost no impact on the increased mortality of childless individuals. This, too, may indicate that selection into parenthood or an accumulation of disadvantage over the life-course is not the only force behind the survival disadvantage among individuals without children, but that support from adult children also matters.

Consistent with previous studies we found adult children’s education to be more closely related to parental mortality than children’s income [14, 22]. Building on this earlier work, our results show that education of adult children is associated with both disease onset in parents and with survival after ill health has begun. Even though the children’s socioeconomic resources seem to matter more for health in old age, the associations with number of adult children remained after adjusting for children’s education and income. This suggests that the number of children, independent of their socioeconomic resources, matters for the survival of their parents, but perhaps through different mechanisms.

In Sweden, elderly care is universally available and almost fully subsidised. Differences in access to health and elderly care are therefore less likely to explain the results than in other contexts. However, a publically financed health care system also comes with limitations of resources and a slim lined organisation that could increase differences between individuals with and without family support. Although cohabitation of adult children with their parents is uncommon in Sweden, the majority of parents has contact with their children at least once per week [27, 28]. Moreover, adult children often become care-givers for their aging parents [11]. Still, it is possible that children and their socioeconomic resources play an even larger role for their parents’ health in countries in which care is not publically financed. In order to gain further insight in the relationship between childlessness, health, and survival in old age we suggest future studies continue looking into mechanisms linking adult children to parental health and focus, for instance, on the different types of support that could affect health in old age. In an era in which childlessness is increasing [29] this is important to inform public health policies and reduce survival inequalities.

This nationwide study confirms that the presence and number of adult children are associated with mortality in old age, with childless individuals being at greatest risk. It adds to previous knowledge showing that the benefit of having children for health in old age seems to arise once individuals have become ill rather than before. In times of rising childlessness and increasing longevity, our findings raise concern about potential care deficits of older childless individuals, particularly those affected by disease. Our results further indicate the potential importance of resources provided by highly educated children for parental health and mortality in old age.