The authors have declared that no competing interests exist.
Conceived and designed the experiments: JL. Performed the experiments: JL MV SC MG BHB CO JO. Analyzed the data: JL. Contributed reagents/materials/analysis tools: JL MV SC MG BHB CO JO. Wrote the first draft of the manuscript: JL. Contributed to the writing of the manuscript: JL MV SC MG BHB CO JO.
Jiong Li and colleagues examine mortality rates in children who lost a parent before 18 years old compared with those who did not using population-based data from Denmark, Sweden, and Finland.
Bereavement by spousal death and child death in adulthood has been shown to lead to an increased risk of mortality. Maternal death in infancy or parental death in early childhood may have an impact on mortality but evidence has been limited to short-term or selected causes of death. Little is known about long-term or cause-specific mortality after parental death in childhood.
This cohort study included all persons born in Denmark from 1968 to 2008 (
Parental death in childhood or adolescence is associated with increased all-cause mortality into early adulthood. Since an increased mortality reflects both genetic susceptibility and long-term impacts of parental death on health and social well-being, our findings have implications in clinical responses and public health strategies.
When someone close dies, it is normal to grieve, to mourn the loss of that individual. Initially, people who have lost a loved one often feel numb and disorientated and find it hard to grasp what has happened. Later, people may feel angry or guilty, and may be overwhelmed by feelings of sadness and despair. They may become depressed or anxious and may even feel suicidal. People who are grieving can also have physical reactions to their loss such as sleep problems, changes in appetite, and illness. How long bereavement—the period of grief and mourning after a death—lasts and how badly it affects an individual depends on the relationship between the individual and the deceased person, on whether the death was expected, and on how much support the mourner receives from relatives, friends, and professionals.
The loss of a life-partner or of a child is associated with an increased risk of death (mortality), and there is also some evidence that the death of a parent during childhood leads to an increased mortality risk in the short term. However, little is known about the long-term impact on mortality of early parental loss or whether the impact varies with the type of death—a natural death from illness or an unnatural death from external causes such as an accident—or with the specific cause of death. A better understanding of the impact of early bereavement on mortality is needed to ensure that bereaved children receive appropriate health and social support after a parent's death. Here, the researchers undertake a nationwide cohort study in three Nordic countries to investigate long-term and cause-specific mortality after parental death in childhood. A cohort study compares the occurrence of an event (here, death) in a group of individuals who have been exposed to a particular variable (here, early parental loss) with the occurrence of the same event in an unexposed cohort.
The researchers obtained data on everyone born in Denmark from 1968 to 2008 and in Sweden from 1973 to 2006, and on most people born in Finland from 1987 to 2007 (more than 7 million individuals in total) from national registries. They identified 189,094 individuals who had lost a parent between the age of 6 months and 18 years. They then estimated the mortality rate ratio (MRR) associated with parental death during childhood or adolescence by comparing the number of deaths in this exposed cohort (after excluding children who died on the same day as a parent or shortly after from the same cause) and in the unexposed cohort. Compared with the unexposed cohort, the exposed cohort had 50% higher all-cause mortality (MRR = 1.50). The risk of mortality in the exposed cohort was increased for most major categories of cause of death but the highest MRRs were seen when the cause of death in children, adolescents, and young adults during follow-up and the cause of parental death were in the same category. Notably, parental unnatural death was associated with a higher mortality risk (MRR = 1.84) than parental natural death (MRR = 1.33). Finally, the exposed cohort had increased all-cause MRRs well into early adulthood irrespective of child age at parental death, and the magnitude of MRRs differed by child age at parental death and by type of death.
These findings show that in three high-income Nordic countries parental death during childhood and adolescence is associated with an increased risk of all-cause mortality into early adulthood, irrespective of sex and age at bereavement and after accounting for baseline characteristics such as socioeconomic status. Part of this association may be due to “confounding” factors—the people who lost a parent during childhood may have shared other unknown characteristics that increased their risk of death. Because the study was undertaken in high-income countries, these findings are unlikely to be the result of a lack of material or health care needs. Rather, the increased mortality among the exposed group reflects both genetic susceptibility and the long-term impacts of parental death on health and social well-being. Given that increased mortality probably only represents the tip of the iceberg of the adverse effects of early bereavement, these findings highlight the need to provide long-term health and social support to bereaved children.
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Bereavement by the death of a close relative is a major life event
We hypothesized that parental death in early life has both short- and long-term impacts on health and social well-being, leading to an increased mortality risk accordingly over time. In addition to the genetic disposition of both physical
The study was approved in Denmark by the Data Protection Agency and the Research Ethics Committee of the Central Region; in Sweden by the Research Ethics Committee (EPN) at the Karolinska Institute; and in Finland by Statistics Finland and the National Institute for Health and Welfare (THL). The study was based on encrypted data, on which the ethics committees do not require informed consent.
We established a population-based cohort study by combining nationwide data from three Nordic countries: Denmark, Sweden, and Finland
We excluded 711 children who died the same day as their parents (of whom 626 [87%] died from motor vehicle accidents, drowning, or other violent causes). We also excluded 94 children who died of the same or a related cause as their parents (defined by the same first two digits in the
The main outcomes of interest were all-cause mortality, cause-specific mortality, and type of death (natural death from diseases and medical conditions, unnatural death from external causes). We obtained information on the cause of death from the Cause of Death Register in each country. In Denmark, the eighth version (ICD-8) was used to categorize cause of death between 1978 and 1993 and the tenth version (ICD-10) between 1994 and 2007. In Sweden, the ICD-8 was used between 1973 and 1986, the ICD-9 between 1987 and 1996, and the ICD-10 between 1997 and 2008. In Finland, the ICD-9 was used between 1987 and 1995 and the ICD-10 between 1996 and 2010
Information on child sex, birth characteristics (birth weight, gestational age, and Apgar score at five minutes, etc.), maternal age, and parity was retrieved from the national Medical Birth Registers (MBRs)
Data were analyzed using log-linear Poisson regression models (SAS Genmod procedure, version 9.2) as an approximation of the Cox regression, as the latter would often be too computationally intensive for a dataset of this size with time-dependent variables
The exposure was treated as a time-varying variable, i.e., all persons were allocated to the unexposed cohort at the beginning of the follow-up (0.5 years of age). Those who lost a parent before they reached 18 years of age would be moved to the exposed cohort from the day when the parent died. All children who did not lose a parent before they reached 18 years of age remained in the unexposed cohort. Follow-up time was counted by days as offset variable in the model. Child age was a categorical variable defined by the age in each calendar year. In some analyses, the length of follow-up time was categorized into six periods (0–2 years, 3–6 years, 7–10 years, 11–14 years, 15–18 years, ≥19 years).
Mortality rate ratios (MRRs) for the exposed and the unexposed were estimated according to all-cause mortality, type of child death (natural death, unnatural death), and cause-specific mortality. When using natural death as response (outcome), unnatural death is a competing event and treated as a censored case. We did the same for cause-specific mortality, performing ten separate analyses for the ten above-mentioned main cause groups. For each of these ten analyses, we separated the exposure into two sub-categories: the first sub-category of “same cause” referred to a cause of parental death that belonged to the same specific-cause group of child mortality and others were grouped into the second exposed sub-category of “not same cause.” For example, if a specific-cause group of child mortality (outcome) was “Infections & parasitic diseases,” the first exposure sub-category was parental death due to “Infections & parasitic diseases,” the second exposure sub-category was parental death due to other causes than “Infections & parasitic diseases.” This approach would to some extent help us to evaluate the role of genetic disposition for cause-specific mortality.
In additional analyses, we examined the MRRs according to specific cause groups of parental death. We further analyzed data according to sub-categories of exposure: child age at parental death (6 months–4 years, 5–10 years, 11–14 years, and 15–18 years), sex of the deceased parent (father, mother), type of parental death (natural death, unnatural death).
We also performed subgroup analyses based on specific characteristics of the study population, such as country, sex of child, child birth characteristics, and maternal socioeconomic status.
The following potential confounders were included in the model: country (Denmark, Sweden, and Finland), sex (male, female), and birth characteristics including birth weight (<2,500 g, 2,500–3,249 g, 3,250–3,999 g, ≥4,000 g), preterm birth (gestational age: <37 weeks, ≥37 weeks), and Apgar score at five minutes (1–8, 9–10). We also included maternal socio-demographic characteristics at childbirth, such as age (≤26, 27–30, ≥31 years), parity (1st, 2nd, 3rd, or higher), education (low [≤9 years], middle [10–14 years], and high [≥15 years] [available for Swedish data from 1990, 1995, 2000, and 2005; for annual Danish data from 1980 to 2007; and for annual Finnish data from 1987 to 2007]), social status (1 = not in labor market; 2 = unskilled worker, 3 = skilled worker and white collar; 4 = high status, such as medium to big business owners, top administrative officials; 9 = missing values; data were available for the periods 1980–2008 in Denmark, 1980, 1985, 1990 in Sweden, and 1990–2007 in Finland), and data on smoking in early pregnancy ([yes, no] was available for the periods 1983–2006 in Sweden, 1991–2007 in Denmark, and 1987–2007 in Finland).
Out of 7,302,013 individuals included in this study, 189,094 (2.6%) lost a parent in the period from 6 months of age to 18 years of age. The exposed and the unexposed cohorts were comparable in terms of most baseline characteristics at birth, except that more mothers of exposed children tended to have a short-term education and high parity, and more mothers of exposed children smoked during pregnancy, and fewer had the highest social status (
Variables | Number Exposed Cohort |
Number Unexposed Cohort |
Denmark | 89,905 (48) | 2,699,902 (37) |
Sweden | 83,639 (44) | 3,296,662 (46) |
Finland | 15,550 (8) | 1,116,355 (16) |
Boy | 96,940 (51) | 3,647,618 (51) |
Girl | 92,154 (49) | 3,465,301 (49) |
Yes | 11,798 (7) | 361,408 (5) |
No | 152,401 (89) | 6,155,416 (91) |
Unknown | 6,103 (4) | 239,344 (4) |
Yes | 16,359 (96) | 6,442,449 (95) |
No | 4,140 (2) | 175,620 (3) |
Unknown | 2,571 (2) | 158,099 (2) |
<2,500 g | 9,360 (6) | 260,756 (4) |
2,500–3,249 g | 43,509 (29) | 1,545,832 (24) |
3,250–3,999 g | 72,055(48) | 3,265,065 (51) |
≥4,000 g | 22,622 (15) | 1,119,185 (18) |
Unknown | 2519 (2) | 160,136 (3) |
≤26 | 67,351 (34) | 2,699,329 (38) |
27–30 | 46,748 (25) | 1,989,534 (28) |
≥31 | 74,881 (40) | 2,412,940 (32) |
Unknown | 114 (<1) | 11,116 (<1) |
1 | 64,206 (34) | 2,554,719 (36) |
2 | 53,611 (28) | 1,483,838 (21) |
≥3 | 67,801 (36) | 3,040,273 (43) |
Unknown | 3476 (2) | 34,089 (<1) |
1–8 | 5,618 (3) | 219,710 (3) |
9–10 | 124,140 (70) | 4,999,175 (78) |
Unknown | 48,412 (27) | 1,198,523 (19) |
Low, ≤9 years | 42,179 (32) | 1,099,544 (21) |
Middle, 10–14 years | 54,924 (42) | 2,584,874 (50) |
High, ≥15 years | 18,035 (14) | 1,057,300 (20) |
Unknown | 16,493 (13) | 432,255 (8) |
Not in labor market | 24,469(17) | 956,976 (16) |
Unskilled workers | 30,168 (21) | 1,191,848 (20) |
Skilled workers/white collars | 33,429 (24) | 1,824,232 (30) |
Top level status | 17,725 (13) | 1,040,598 (17) |
Unknown | 37,842 (25) | 1,055,008 (17) |
Yes | 27,721 (34) | 817,171 (18) |
No | 46,783 (57) | 3,412,915 (75) |
Unknown | 7,206 (9) | 336,262 (7) |
Shown are number of study participants.
Birth weight available period: 1979–2008 in Denmark, 1973–2006 in Sweden, 1987–2007 in Finland; parity available period: 1968–2008 in Denmark, 1973–2006 in Sweden, 1987–2007 in Finland; Gestational age and singleton available period: 1973–2008 in Denmark, 1973–2006 in Sweden, 1987–2007 in Finland. Apgar score at 5 minutes: 1978–2008 in Denmark, 1973–2006 in Sweden, 1987–1989, 2003–2007 in Finland.
Maternal education available period: 1980–2007 in Denmark, 1990, 1995, 2000, 2005 in Sweden, and 1987–2007 in Finland; Maternal smoking during pregnancy available period: 1991–2007 in Denmark, 1982–2006 in Sweden, 1987–2007 in Finland; Maternal social status available period: 1980–2008 in Denmark, 1980, 1985, 1990 in Sweden, 1990–2007 in Finland.
During the follow-up period, 39,683 individuals included in this study died. Compared with the unexposed cohort, the exposed cohort had a 50% higher all-cause mortality (MRR = 1.50, 95% CI 1.43–1.58) (
Outcome (Child Mortality) | Exposure (Type of Parental Death) | Cases/Person Years (Rate, 1/105) | MRR (95% CI) Model 1 |
MRR (95% CI) Model 2 |
Parental natural death | 995/1,733,666 (57.4) | 1.63 (1.53–1.74) |
1.33 (1.24–1.41) |
|
Parental unnatural death | 670/904,568 (74.1) | 2.21 (2.04–2.38) |
1.84 (1.71–2.00) |
|
37,988/129,341,810 (29.4) | 1.0 (ref) | 1.0 (ref) | ||
Parental natural death | 394/1,733,371 (22.7) | 1.48 (1.29–1.70)8 | 1.44 (1.26–1.67) |
|
Parental unnatural death | 197/904,329 (21.8) | 1.53 (1.38–1.69)8 | 1.45 (1.30–1.60) |
|
18,709 (14.5) | 1.0 (ref) | 1.0 (ref) | ||
Parental natural death | 495/1,733,666 (28.5) | 1.79 (1.63–1.95) |
1.32 (1.20–1.44) |
|
Parental unnatural death | 394/904,568 (43.6) | 2.92 (2.63–3.22) |
2.15 (1.94–2.38) |
|
15,890 (12.3) | 1.0 (ref) | 1.0 (ref) |
MRRs were adjusted for country, age, and sex.
MRRs were adjusted for country, age, sex, calendar year period, birth outcomes (birth weight, the Apgar score at 5 minutes, preterm birth), and maternal variables (age, parity, education, and social status).
*
Sex of Deceased Parent | Child Sex | Cases/Person Years (Rate, 1/105) | MRR (95% CI) Model 1 |
MRR (95% CI) Model 2 |
Boys only | 1,203/1,379,764 (87.2) | 1.60 (1.51–1.70) |
1.54 (1.45–1.64) |
|
Girls only | 492/1,299,276 (37.9) | 1.52 (1.39–1.67) |
1.43 (1.30–1.56) |
|
Boys only | 819/964,273 (84.9) | 1.67 (1.51–1.85) |
1.58 (1.43–1.76) |
|
Girls only | 327/915,951 (35.7) | 1.45 (1.30–1.62) |
1.37 (1.23–1.54) |
|
Boys only | 384/415,491 (92.4) | 1.63 (1.48–1.80) |
1.55 (1.40–1.72) |
|
Girls only | 165/386,325 (42.7) | 1.68 (1.44–1.97) |
1.51 (1.29–1.78) |
MRRs were adjusted for country, age, and sex.
MRRs were adjusted for country, age, sex, calendar year period, birth outcomes (birth weight, the Apgar score at 5 minutes, preterm birth), and maternal variables (age, parity, education, and social status).
*
Although the absolute mortality rate was twice as high among boys (87.2/105 person-years) as among girls (37.9/105 person-years), similar MRR estimates were observed in the analyses stratified by child sex (in boys MRR = 1.54, 95% CI 1.45–1.64, in girls MRR = 1.43, 95% CI 1.30–1.56) (
Variables | Cases in the Exposed/Unexposed | Mortality Rate in the Exposed/Unexposed | MRR |
Denmark | 1,053/19,210 | 73.4/35.7 | 1.53 (1.44–1.63) |
Sweden | 582/15,629 | 51.6/25.8 | 1.47 (1.35–1.60) |
Finland | 108/2,769 | 72.5/46.7 | 1.39 (1.14–1.70) |
Yes | 108/2,769 | 72.6/46.7 | 1.39 (1.14–1.70) |
No | 1,078/27,662 | 54.9/26.2 | 1.53 (1.43–1.63) |
Yes | 1,197/30,456 | 56.4/27.4 | 1.51 (1.42–1.60) |
No | 21/855 | 43.4/32.6 | 1.10 (0.70–1.63) |
<2,500 g | 65/2,416 | 59.7/57.8 | 1.04 (0.81–1.35) |
2,500–3,249 g | 273/7,310 | 51.8/28.2 | 1.47 (1.30–1.66) |
3,250–3,999 g | 393/11,920 | 45.9/22.3 | 1.50 (1.35–1.66) |
≥4,000 g | 144/3,941 | 55.7/22.3 | 1.71 (1.45–2.03) |
1–8 | 57/2,823 | 64.8/47.2 | 1.09 (0.83–1.44) |
9–10 | 722/2,817 | 48.6/24.2 | 1.48 (1.37–1.59) |
Unknown | 28/19,795 | 44.5/16.3 | 2.13 (1.40–3.27) |
≤26 | 766/19,340 | 73.4/34.0 | 1.56 (1.45–1.68) |
27–30 | 380/9,446 | 57.3/25.8 | 1.47 (1.34–1.60) |
≥31 | 573/9,092 | 56.4/25.1 | 1.43 (1.32–1.56) |
1 | 591/15,774 | 62.4/28.5 | 1.58 (1.45–1.74) |
2 | 539/13,350 | 60.5/28.5 | 1.50 (1.38–1.64) |
≥3 | 474/8,570 | 64.0/32.2 | 1.41 (1.29–1.55) |
≤9 years | 269/6,899 | 53.3/32.9 | 1.35 (1.19–1.53) |
10–14 years | 289/10,709 | 45.3/23.6 | 1.51 (1.34–1.70) |
≥15 years | 63/3141 | 32.9/21.2 | 1.32 (1.04–1.72) |
Not in labor market | 191/5,338 | 55.7/31.1 | 1.42 (1.22–1.65) |
Unskilled workers | 196/5,404 | 54.3/25.4 | 1.50 (1.31–1.75) |
Skilled workers/white collars | 157/6,658 | 40.7/22.0 | 1.36 (1.16–1.61) |
Top level status | 97/4,049 | 43.9/24.3 | 1.24 (1.01–1.53) |
Yes | 108/3,062 | 46.3/25.0 | 1.47 (1.20–1.80) |
No | 126/7,929 | 33.6/18.1 | 1.52 (1.26–1.82) |
MRRs were adjusted for country, age, sex, calendar year period, birth outcomes (birth weight, the Apgar score at 5 minutes, preterm birth), and maternal variables (age, parity, education, and social status).
Birth weight available period: 1979–2008 in Denmark, 1973–2006 in Sweden, 1987–2007 in Finland; parity available period: 1968–2008 in Denmark, 1973–2006 in Sweden, 1987–2007 in Finland; Gestational age and singleton available period: 1973–2008 in Denmark, 1973–2006 in Sweden, 1987–2007 in Finland. Apgar score at 5 minutes: 1978–2008 in Denmark, 1973–2006 in Sweden, 1987–1989, 2003–2007 in Finland; Maternal education available period: 1980–2007 in Denmark, 1990, 1995, 2000, 2005 in Sweden, and 1987–2007 in Finland; Maternal smoking during pregnancy available period: 1991–2007 in Denmark, 1982–2006 in Sweden, 1987–2007 in Finland; Maternal social status available period: 1980–2008 in Denmark, 1980, 1985, 1990 in Sweden, 1990–2007 in Finland.
*
Variables | MRR |
Denmark | 1.21 (1.17–1.26) |
Sweden | 1.0 (ref) |
Finland | 1.06 (0.99–1.16) |
Boy | 1.78 (1.74–1.81) |
Girl | 1.0 (ref) |
Yes | 1.12 (1.06–1.17) |
No | 1.0 (ref) |
Yes | 0.79 (0.73–0.85) |
No | 1.0 (ref) |
<2,500 g | 2.14 (2.03–2.27) |
2,500–3,249 g | 1.22 (1.19–1.28) |
3,250–3,999 g | 1.0 (ref) |
≥4,000 g | 0.97 (0.93–0.99) |
1–8 | 1.99 (1.87–2.06) |
9–10 | 1.0 (ref) |
≤26 | 1.23 (1.20–1.25) |
27–30 | 1.02 (1.00–1.05) |
≥31 | 1.0 (ref) |
1 | 1.0 (ref) |
2 | 1.09 (1.06–1.11) |
≥3 | 1.31 (1.28–1.35) |
≤9 years | 1.0 (ref) |
10–14 years | 0.82 (0.77–0.84) |
≥15 years | 0.80 (0.76–0.85) |
Not in labor market | 1.05 (1.01–1.09) |
Unskilled workers | 1.0 (ref) |
Skilled workers/white collars | 0.92 (0.86–0.97) |
Top level status | 0.87 (0.84–0.89) |
Yes | 1.21 (1.15–1.24) |
No | 1.0 (ref) |
MRRs were adjusted for country, age, sex, calendar year period, birth outcomes (birth weight, the Apgar score at 5 minutes, preterm birth), and maternal variables (age, parity, education, and social status).
Birth weight available period: 1979–2008 in Denmark, 1973–2006 in Sweden, 1987–2007 in Finland; parity available period: 1968–2008 in Denmark, 1973–2006 in Sweden, 1987–2007 in Finland; Gestational age and singleton available period: 1973–2008 in Denmark, 1973–2006 in Sweden, 1987–2007 in Finland. Apgar score at 5 minutes: 1978–2008 in Denmark, 1973–2006 in Sweden, 1987–1989, 2003–2007 in Finland; Maternal education available period: 1980–2007 in Denmark, 1990, 1995, 2000, 2005 in Sweden, and 1987–2007 in Finland; Maternal smoking during pregnancy available period: 1991–2007 in Denmark, 1982–2006 in Sweden, 1987–2007 in Finland; Maternal social status available period: 1980–2008 in Denmark, 1980, 1985, 1990 in Sweden, 1990–2007 in Finland.
*
The exposed cohort had higher mortality risks from most major groups of cause of death than the unexposed cohort (
Outcome (Cause of Death in the Offspring) | Exposure (Cause of Parental Death) |
Number Deaths in the Exposed/the Unexposed | Rate in the Exposed/the Unexposed (1/105) | MRR (95% CI) |
Same cause | 0/998 | 0/0.77 | — | |
Not same cause | 21/998 | 0.78/0.77 | 1.40 (0.90–2.17) | |
Same cause | 4/2,166 | 10.5/1.66 | 7.26 (2.94–15.91) |
|
Not same cause | 72/2,166 | 2.49/1.66 | 1.64 (1.24–2.14) |
|
Same cause | 2/956 | 2.11/0.74 | 2.12 (0.53–8.51) | |
Not same cause | 18/956 | 0.69/0.74 | 2.10 (0.61–1.55) | |
Same cause | 4/442 | 2.13/0.34 | 4.65(1.73–12.47) |
|
Not same cause | 28/442 | 1.09/0.34 | 2.08 (1.42–3.05) |
|
Same cause | 10/960 | 1.70/0.74 | 1.87 (1.00–3.51) |
|
Not same cause | 46/960 | 1.97/0.74 | 1.71 (1.27–2.31) |
|
Same cause | 67/5,312 | 8.31/4.11 | 1.71 (1.34–2.18) |
|
Not same cause | 105/5,312 | 5.60/4.11 | 1.16 (0.96–1.41) | |
Same cause | 1/1,085 | 1.19/0.83 | 1.25 (0.18–8.89) | |
Not same cause | 32/1,085 | 1.22/0.83 | 1.26 (0.87–1.82) | |
Same cause | 1/340 | 1.05/0.26 | 3.77 (1.56–9.08) |
|
Not same cause | 24/340 | 0.91/0.26 | 1.64 (1.28–2.08) |
|
Same cause | 21/6,647 | 7.77/5.12 | 1.21 (0.78–1.85) | |
Not same cause | 273/6,647 | 10.95/5.12 | 1.25 (1.10–1.41) |
|
Same cause | 64/3,536 | 10.03/2.72 | 2.78 (2.17–3.57) |
|
Not same cause | 209/3,536 | 9.23/2.72 | 1.57 (1.36–1.81) |
Same cause: parental death cause is of same cause group as the child death cause; Not same cause: parental death cause is not of same cause group as the child death cause.
MRRs were adjusted for country, age, sex, calendar year period, birth outcomes (birth weight, the Apgar score at 5 minutes, preterm birth), and maternal variables (age, parity, education, and social status).
*
All-cause mortality in the exposed cohort was increased for almost all specific causes of parental death, albeit the MRRs were not statistically significant for several causes like infections or diseases of the nervous system (
(A) All-cause mortality in children; (B) mortality from natural death in children; (C) mortality from unnatural death in children (MRRs were adjusted for country, age, sex, calendar year period, birth outcomes [birth weight, the Apgar score at 5 minutes, preterm birth], and maternal variables [age, parity, education, and social status]).
Child Mortality | Exposure | Cases | MRR (95% CI) Model 1 |
MRR (95% CI) Model 2 |
Parental suicide | 64 | 3.06 (2.39–3.93) |
2.87 (2.24–3.67) |
|
Parental accidental death | 14 | 1.66 (0.96–2.86) | 1.53 (0.89–2.65) | |
Parental suicide | 49 | 1.43 (1.06–1.86) |
1.37 (1.03–1.82) |
|
Parental accidental death | 21 | 1.49 (0.97–2.31) | 1.41 (0.92–2.17) |
MRRs were adjusted for country, age, and sex.
MRRs were adjusted for country, age, sex, calendar year period, birth outcomes (birth weight, the Apgar score at 5 minutes, preterm birth), and maternal variables (age, parity, education, and social status).
*
The exposed cohort had increased all-cause mortality MRRs well into early adulthood, irrespective of child age at parental death. The magnitude of MRRs differed by child age at parental death and type of death. For natural death, there was a tendency that MRRs increased over follow-up time, while those who were exposed at advanced child age groups tended to have higher MRRs in the later periods of follow-up. For unnatural death, those exposed before 5 years of age mostly had higher MRRs than others, especially at the beginning years of follow-up. Those exposed at age 15–18 also had relatively high MRRs throughout the follow-up periods (
(A) All-cause death MRRs over follow-up, by age at bereavement; (B) natural death MRRs over follow-up, by age at bereavement; (C) unnatural death MRRs over follow-up, by age at bereavement (MRRs were adjusted for country, age, sex, calendar year period, birth outcomes [birth weight, the Apgar score at 5 minutes, preterm birth], and maternal variables [age, parity, education, and social status]).
In this large population-based cohort study, parental death in childhood and adolescence was associated with an increased risk of all-cause mortality that persisted into early adulthood, irrespective of sex and age at bereavement and after accounting for the effects of specific baseline characteristics like socioeconomic status and birth characteristics. The elevated risks were seen for almost all major cause of death groups and the highest risks were observed when children died from the same cause as the parent. Parental unnatural death was associated with a higher risk than parental natural death. Increased risks of child mortality were observed for almost all major cause groups of parental death.
The increased overall mortality following parental death is in line with the suggestions from historical populations and from low-income countries
How parental loss in childhood influences mortality risk from physical diseases is not well studied
The high MRR of unnatural death from external causes, in particular suicide, was seen in individuals who had lost a parent owing to suicide, which may reflect a heritability of mental health problems or familial transmission of impulsive aggression
Reactions to bereavement are expected to diminish but not always to disappear over time
Our study has a number of strengths. We combined nationwide data from three Nordic countries on virtually all study participants who were followed for up to 42 years without loss to follow-up
Our findings should also be interpreted in the light of limitations. First, we lacked information on some baseline factors, such as the quality of the parent-child relationship, common lifestyle factors, and the physical environment like residential settings. We hope that adjustment for maternal factors (education and social status) and family size (parity) may reduce the effects of these unmeasured confounders to some extent. Second, we had no data on post-loss changes in families, network, lifestyle factors, or risky behaviors, etc. However, these changes may be on the pathways from exposure to outcome, which should not be adjusted
To conclude, parental death in childhood was associated with a long-lasting increased mortality risk from both external causes and diseases, regardless of age and sex of the child and the deceased parent, cause of parental death, as well as population characteristics like socioeconomic background. It should be acknowledged that that the increased mortality represents only the tip of the iceberg effects
We thank Esben Agerbo for his advice on statistical analyses.
International Statistical Classification of Diseases and Related Health Problems (ICD) code
mortality rate ratio