Birth Spacing and Parents' Physical and Mental Health: An Analysis Using Individual and Sibling Fixed Effects.

An extensive literature has examined the relationship between birth spacing and subsequent health outcomes for parents, particularly for mothers. However, this research has drawn almost exclusively on observational research designs, and almost all studies have been limited to adjusting for observable factors that could confound the relationship between birth spacing and health outcomes. In this study, we use Norwegian register data to examine the relationship between birth spacing and the number of general practitioner consultations for mothers' and fathers' physical and mental health concerns immediately after childbirth (1-5 and 6-11 months after childbirth), in the medium term (5-6 years after childbearing), and in the long term (10-11 years after childbearing). To examine short-term health outcomes, we estimate individual fixed-effects models: we hold constant factors that could influence parents' birth spacing behavior and their health, comparing health outcomes after different births to the same parent. We apply sibling fixed effects in our analysis of medium- and long-term outcomes, holding constant mothers' and fathers' family backgrounds. The results from our analyses that do not apply individual or sibling fixed effects are consistent with much of the previous literature: shorter and longer birth intervals are associated with worse health outcomes than birth intervals of approximately 2-3 years. Estimates from individual fixed-effects models suggest that particularly short intervals have a modest negative effect on maternal mental health in the short term, with more ambiguous evidence that particularly short or long intervals might modestly influence short-, medium-, and long-term physical health outcomes. Overall, these results are consistent with small to negligible effects of birth spacing behavior on (non-pregnancy-related) parental health outcomes.

Parental income gradients in child and adolescent mortality: Norwegian trends over half a century.

BACKGROUND: Child mortality has declined rapidly over the last century in many high-income countries. However, little is known about the socio-economic differences in this decline and whether these vary across causes of death. METHODS: We used register data that included all Norwegian births between 1968 and 2010 (2.1 million), and we analysed how all-cause and cause-specific child (0-4 years) and adolescent (5-20 years) mortality rates vary with relative parental income the year before the birth. RESULTS: Child and adolescent all-cause mortality decreased with increasing parental relative income within all birth cohorts. Among children aged 0-4 years, the socio-economic gradient in all-cause mortality and in mortality due to external causes, sudden infant deaths and perinatal factors declined over the period, while there was no systematic decline in mortality from congenital malformations. Among children aged 5-20 years, the gradient did not weaken similarly, although there were indications of declines in the socio-economic gradient related to all-cause deaths and deaths because of suicides and other external causes. While the absolute differences in mortality declined over time, the relative differences remained stable. CONCLUSIONS: Although children of low-income parents still have elevated mortality, there has been a large reduction in child mortality in all socio-economic groups across 50 years for all causes combined and most of the groups of specific causes of death.

Number of children and disability pension due to mental and musculoskeletal disorders: A longitudinal register-based study in Norway.

Earlier research has documented a relationship between parity and all-cause mortality, as well as parity and cause-specific mortality (e.g. cancer and cardiovascular disease mortality). Less is known about the relationship between parity and two very common (but less deadly) types of disorder: mental and musculoskeletal. We examine the association between parity and risk of disability pensioning from all causes and due to mental or musculoskeletal disorders, using Norwegian register data. In addition to controlling for adult socio-demographic characteristics, we control for unobserved confounding from family background by estimating sibling fixed-effects models. We find a higher risk of disability pensioning among the childless and those with one child than for parents with two children, both for all causes combined and for mental disorders. Childless men and fathers with one child also experience excess risk of being pensioned due to musculoskeletal disorders. For mental disorders, we find a positive association with high parity, particularly for men.

Mental health benefits of cohabitation and marriage: A longitudinal analysis of Norwegian register data.

The aim is to examine how mental health is affected by cohabitation and marriage. Individual fixed-effects models are estimated from Norwegian register data containing information about consultations with a general practitioner because of mental health conditions in 2006-19. Mental health, as indicated by annual number of consultations, improves over several years before cohabitation. For those marrying their cohabiting partner, there is a weak further reduction in consultations until the wedding, but no decline afterwards. In other words, formalization of the union does not seem to confer additional mental health benefits. However, marriage may be considered a marker of favourable earlier development in mental health. In contrast, there is further improvement after direct marriage, as well as stronger improvement over the years just preceding direct marriage. Patterns are quite similar for women and men. Overall, the results suggest that the mental health benefits of cohabitation and marriage are similar.Supplementary material for this article is available at: https://dx.doi.org/10.1080/00324728.2022.2063933. Note: numbers in brackets refer to supplementary notes that can be found at the end of the supplementary material.

Effects of previous birth interval length on child outcomes can be estimated in a sibling analysis even when there are only two siblings.

BACKGROUND: There is much interest in how the length of the previous birth interval affects various child outcomes, and it has become increasingly common to estimate such effects from sibling models. This is because one then controls for unobserved determinants of the outcome that are shared between the siblings and linked to the birth interval length. However, it is a common idea that such effects can only be estimated from data on families with three or more children. OBJECTIVE: The goal of this paper is to show, through an intuitive argument and a simulation experiment, that it is possible to estimate effects of birth interval only from families with two children. METHODS: Observations are simulated from two equations for fertility and one equation for child mortality. The fertility equations include a random term that is assumed to be correlated with the random term in the mortality equation. Mortality models are then estimated from the simulated observations. This is done 1000 times, and the averages of the 1000 sets of estimates are calculated. RESULTS: The simulation experiment illustrates that it is indeed possible (by using a model specification that takes into account that no birth interval is defined for the first birth) to estimate birth interval effects in sibling models even when the data include only families with two children. CONCLUSION: It is good news that families with only two children can contribute to the estimation of birth interval effects. This is because, with a broader basis for the estimation, the precision is improved and there is less reason for concern about the general relevance of the estimates. An important limitation, however, is that it is potentially problematic to control for maternal age in a sibling model estimated only for the first and second child.

Association of Childbearing With a Short-Term Reduced Risk of Crohn Disease in Mothers.

Our aim in this study was to analyze the importance of childbearing for risk of inflammatory bowel disease. Using data from the Norwegian Population Register and the Norwegian Patient Register, we fitted discrete-time hazard models for diagnosis of Crohn disease (CD) or ulcerative colitis (UC) among men and women aged 18-81 years in 2011-2016. Year and various sociodemographic factors were controlled for. The data included 4,304 CD cases and 8,866 UC cases. Women whose youngest child was ≤4 years of age had lower CD risk the following year than childless women (odds ratio (OR) = 0.73, 95% confidence interval (CI): 0.62, 0.86). There was no such reduction in CD risk among fathers. Men whose youngest child was aged ≥20 years had higher risks of CD (OR = 1.22, 95% CI: 1.01, 1.49) and UC (OR = 1.15, 95% CI: 1.02, 1.30) than childless men. UC risk was also increased among men whose youngest child was aged ≤4 years (OR = 1.14, 95% CI: 1.02, 1.27). The short-term reduction in women's CD risk after a birth may reflect biological effects of pregnancy. Alternatively, it may reflect residual confounding or lifestyle effects of parenthood that are of special relevance for CD in women. In particular, differences in use of oral contraceptives (which it was not possible to control for) may have contributed to the observed pattern.

The demographics of assisted reproductive technology births in a Nordic country.

STUDY QUESTION: What are the socio-demographic characteristics of families in Norway who have children after assisted reproductive technology (ART), and have these characteristics changed over time? SUMMARY ANSWER: Parents who conceive through ART in Norway tend to be advantaged families, and their socio-demographic profile has not changed considerably over the period 1985-2014. WHAT IS KNOWN ALREADY: A small number of studies show that couples who conceive through ART tend to be socio-economically advantaged. STUDY DESIGN, SIZE, DURATION: Norwegian Population Register, the Medical Birth Register and the national data bases were linked to study all live births in Norway between 1985 and 2014. PARTICIPANTS/MATERIALS, SETTING, METHODS: The sample consisted of 1 757 768 live births. Simple bivariate analyses were performed to describe the socio-demographic characteristics of parents who conceived through ART and changes in these characteristics over the time period 1985-2014. We used linear probability models to estimate the association between parental income and giving birth after ART from 2000 to 2014, before and after adjustment for maternal age at delivery, education and area of residence. MAIN RESULTS AND THE ROLE OF CHANCE: Parents conceiving through ART were more likely to be older, with the highest levels of income and education, and married. Their socio-demographic profiles did not change considerably during the period 1985-2014. In the unadjusted model, parents belonging to the top income quartile were 4.2 percentage points more likely (95% CI: 4.1 to 4.3) to have conceived through ART than parents who belonged to the bottom income quartile. Adjustment for maternal age only partially reduced the income disparities (for the top income quartile by 35% (ß = 2.7 with 95% CI: 2.5 to 2.8)). Additional adjustment for maternal education, marital status and area of residence did not further attenuate the associations. LIMITATIONS, REASONS FOR CAUTION: The data does not enable us to tell whether the lower numbers of children conceived through ART amongst more disadvantaged individuals is caused by lower success rates with ART treatment, lower demand of ART services or barriers faced in access to ART. The study focuses on Norway, a context characterised by high subsidisation of ART services. WIDER IMPLICATIONS OF THE FINDINGS: Even though in Norway access to ART services is highly subsidised, the results highlight important and persisting social inequities in use of ART. The results also indicate that children born after ART grow up in resourceful environments, which will benefit their development and well-being. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by European Research Council agreement n. 803959 (to A.G.), by Economic and Social Research Council grant ES/M001660/1 and by the Research Council of Norway through its Centres of Excellence funding scheme, project number 262700. The authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER: Not applicable.

The association between parity, CVD mortality and CVD risk factors among Norwegian women and men.

BACKGROUND: Several studies have shown that women and men with two children have lower mortality than the childless, but there is less certainty about mortality, including CVD mortality, at higher parities and meagre knowledge about factors underlying the parity-mortality relationship. METHODS: The association between parity and CVD mortality was analyzed by estimating discrete-time hazard models for women and men aged 40-80 in 1975-2015. Register data covering the entire Norwegian population were used, and the models included a larger number of relevant sociodemographic control variables than in many previous studies. To analyze the relationship between parity and seven CVD risk factors, logistic models including the same variables as the mortality models were estimated from the CONOR collection of health surveys, linked to the register data. RESULTS: Men (but not women) who had four or more children had higher mortality from CVD than those with two, although this excess mortality was not observed for the heart disease sub-group. Overweight, possibly in part a result of less physical activity, seems to play a role in this. All CVD risk factors except smoking and alcohol may contribute to the relatively high CVD mortality among childless. CONCLUSIONS: Childbearing is related to a number of well-known CVD risk factors, and becoming a parent or having an additional child is, on the whole, associated with lower-or at least not higher-CVD mortality in Norway. However, for men family sizes beyond three children are associated with increased CVD mortality, with risks of overweight one possible pathway.

Children's age at parental divorce and depression in early and mid-adulthood.

This study aimed to assess whether children's age at their parents' divorce is associated with depression in early and mid-adulthood, as indicated by medication purchase. A sibling comparison method was used to control for unobserved factors shared between siblings. The data were extracted from the Norwegian Population Register and Norwegian Prescription Database and included about 181,000 individuals aged 20-44 who had experienced parental divorce and 636,000 who had not. Controlling for age in 2004, sex, and birth order, children who were aged 15-19 when their parents divorced were 12 per cent less likely to purchase antidepressants as adults in 2004-08 than those experiencing the divorce aged 0-4. The corresponding reduction for those aged 20+ at the time of divorce was 19 per cent. However, the association between age at parental divorce and antidepressant purchases was only evident among women and those whose mothers had low education.

New evidence about effects of reproductive variables on child mortality in sub-Saharan Africa.

There is still considerable uncertainty about how reproductive factors affect child mortality. This study, based on Demographic and Health Survey data from 28 countries in sub-Saharan Africa, shows that mortality is highest for firstborn children with very young mothers. Other children with young mothers, or of high birth order, also experience high mortality. Net of maternal age and birth order, a short preceding birth interval is associated with above average mortality. These patterns change, however, if time-invariant unobserved mother-level characteristics of importance for both mortality and fertility are controlled for in a multilevel-multiprocess model. Most importantly, there are smaller advantages associated with longer birth intervals and being older at first birth. The implications of alternative reproductive 'strategies' are discussed, taking into account that if the mother is older at birth, the child will also be born in a later calendar year, when mortality may be lower.

Fertility history and use of antidepressant medication in late mid-life: a register-based analysis of Norwegian women and men.

OBJECTIVES: Life course influences on later life depression may include parenting trajectories. We investigate associations between number and timing of births and use of antidepressant medication in late mid-life using data on the whole Norwegian population. METHODS: We estimated logistic regression models to analyse variations in the purchase of antidepressants between 2004 and 2008 by timing of births and number of children among women and men aged 45-73, using Norwegian population register data. We controlled for age, education, marital and partnership status, and (in some models) family background shared among siblings. RESULTS: Mothers and fathers of two or more children were generally less likely to purchase antidepressants than the childless. Mothers who started childbearing before age 22 were an exception, although according to sibling models they were not more likely to purchase antidepressants. All models showed that women who became mothers before age 26 and had only one child had higher odds of medication purchase than the childless. Older age at first birth was generally associated with lower risks of antidepressant purchase. CONCLUSION: This analysis of high-quality data for a national population indicates that early motherhood, childlessness and low parity are associated with higher usage of antidepressants in late mid-life. Our data did not allow identification of mediating pathways, and we lacked information on early mental and physical health and some other potentially important confounders not shared between siblings. Furthermore purchase of antidepressants is not a perfect indicator of depression. Those concerns aside, the results suggest complex effects of fertility on depression that merit further investigation.

Childbearing impeded education more than education impeded childbearing among Norwegian women.

In most societies, women at age 39 with higher levels of education have fewer children. To understand this association, we investigated the effects of childbearing on educational attainment and the effects of education on fertility in the 1964 birth cohort of Norwegian women. Using detailed annual data from ages 17 to 39, we estimated the probabilities of an additional birth, a change in educational level, and enrollment in the coming year, conditional on fertility history, educational level, and enrollment history at the beginning of each year. A simple model reproduced a declining gradient of children ever born with increasing educational level at age 39. When a counterfactual simulation assumed no effects of childbearing on educational progression or enrollment (without changing the estimated effects of education on childbearing), the simulated number of children ever born decreased very little with increasing completed educational level, contrary to data. However, when another counterfactual simulation assumed no effects of current educational level and enrollment on childbearing (without changing the estimated effects of childbearing on education), the simulated number of children ever born decreased with increasing completed educational level nearly as much as the decrease in the data. In summary, in these Norwegian data, childbearing impeded education much more than education impeded childbearing. These results suggest that women with advanced degrees have lower completed fertility on the average principally because women who have one or more children early are more likely to leave or not enter long educational tracks and never attain a high educational level.

The effects of earlier income variation on mortality: an analysis of Norwegian register data.

Several studies have shown a positive relationship between mortality and episodes of income decline, unemployment, or poverty shortly before death or in the more distant past. Our objective was to analyse the mortality effects of earlier income changes more generally, net of the overall level. We used Norwegian register data that included individual histories of annual labour income and focused on mortality among men aged 50-69 in 1990-2002. Men in this age group who, during the preceding 15 years, had experienced at least two substantial falls in income as well as at least one substantial increase, or vice versa, experienced an excess mortality of 17 per cent. For men who experienced fewer changes, there were only weak indications of excess mortality. Variation dominated by falls in income did not have a more adverse effect than variation dominated by rises.

Union Status and Disability Pension.

A lot is known about the association between marital status and mortality, and some of these studies have included data on cohabitation. Studies on the association with health problems, rather than mortality, are often based on self-reported health outcomes, and results from these studies are mixed. As cohabitation is now widespread, more studies that include data on cohabitation are needed. We use Norwegian register data that include detailed information about union status and all cases of disability pensioning from 2005 to 2016. We employ Cox regression analysis and a within-family design in order to control for hard to measure childhood characteristics. Compared to the married, the cohabiting have a somewhat higher risk of receiving disability pension due to mental disorders, and for men also due to physical disorders. Receipt of disability pension is most common among the never married, especially for men. The association between union status and disability pensioning is stronger for mental than for physical disorders.

Maternal age and the risk of low birthweight and pre-term delivery: a pan-Nordic comparison.

BACKGROUND: Advanced maternal age at birth is considered a risk factor for adverse birth outcomes. A recent study applying a sibling design has shown, however, that the association might be confounded by unobserved maternal characteristics. METHODS: Using total population register data on all live singleton births during the period 1999-2012 in Denmark (N = 580 133; 90% population coverage), Norway (N = 540 890) and Sweden (N = 941 403) and from 2001-2014 in Finland (N = 568 026), we test whether advanced maternal age at birth independently increases the risk of low birthweight (LBW) (<2500 g) and pre-term birth (<37 weeks gestation). We estimated within-family models to reduce confounding by unobserved maternal characteristics shared by siblings using three model specifications: Model 0 examines the bivariate association; Model 1 adjusts for parity and sex; Model 2 for parity, sex and birth year. RESULTS: The main results (Model 1) show an increased risk in LBW and pre-term delivery with increasing maternal ages. For example, compared with maternal ages of 26-27 years, maternal ages of 38-39 years display a 2.2, 0.9, 2.1 and 2.4 percentage point increase in the risk of LBW in Denmark, Finland, Norway and Sweden, respectively. The same patterns hold for pre-term delivery. CONCLUSIONS: Advanced maternal age is independently associated with higher risk of poor perinatal health outcomes even after adjusting for all observed and unobserved factors shared between siblings.

Is mortality after childhood cancer dependent on social or economic resources of parents? A population-based study.

Diagnostic and treatment protocols for childhood cancer are generally standardized, and therefore, survival ought to be fairly equal across social strata in societies with free public health care readily available. Nevertheless, our study explores whether there are disparities in mortality after childhood cancer in Norway depending on socioeconomic status of parents. Limited knowledge on differentials exists from earlier analyses. Discrete-time hazard regression models for all-cause mortality for the first 10 years after diagnosis were estimated for all Norwegian children (younger than 20 years), who were diagnosed with cancer during 1974-2007 (N = 6,280), using data from five national registers. Mortality was reduced by about 15% for children with highly educated mothers and children without siblings. These effects were most pronounced for cancers predicted to encompass intense, long-lasting treatments resulting in chronic health problems. Neither earnings nor the marital status of parents affected children's survival. This large, registry-based study suggests that time constraints and various noneconomic rewards of parents from their education appears to have an impact on childhood cancer survival. It may be that children with resourceful parents are healthier at the outset and/or are more likely to avoid later health problems. It may also be that children of well-informed and strongly involved parents are offered better treatment or are able to make better use of what is offered, for instance, by adhering more closely to recommendations for follow-up treatment. The possibility of such differentials in offered and actual treatment should be addressed in future research.

Trends in educational inequalities in mortality, seven types of cancers, Norway 1971-2002.

BACKGROUND: Knowledge about educational disparities in deaths from specific cancer sites is incomplete. Even more scant is information about time trends in educational patterns in specific cancer mortality. This study examines educational inequalities in Norway 1971-2002 for mortality in lung and larynx, colorectal, stomach, melanoma, prostate, breast and cervix uteri cancer. METHODS: A data file encompassing all Norwegian inhabitants registered some time during 1971-2002 while aged 45-74 was constructed with linked information from administrative registers. During an exposure of more than 40 millions person-years, about 87,000 deaths in the analysed cancer types were registered. Absolute and relative inequalities during three periods were analysed by age-standardized deaths rates, hazard regression odds ratios and Relative Index of Inequality. RESULTS: Educational inequalities in lung and related cancer mortality widened considerably from the 1970s to the 1990s for both sexes. The moderate educational gradient for stomach and cervix uteri cancer persisted, as did the weak gradient for colorectal cancer. No educational differences in prostate cancer were observed in any of the time periods. The modest inverse educational gradients in deaths from breast cancer and melanoma remained at the same level. CONCLUSION: Among the seven cancer types examined in this study, only lung cancer mortality showed a clear widening in educational disparities. As lung cancer mortality constitutes a large proportion of all cancer deaths, this increase may result in larger disparities for overall cancer mortality. Some explanations for the observed patterns in cancer mortality are suggested.

Sex Differences in Childlessness in Norway: Identification of Underlying Demographic Drivers.

In Norway, as in many other rich countries, childlessness is more common among men than women and has also increased more among men. Over the last 15 years, the gap in childlessness between 45-year-old women and men has widened from 5.8 to 10.2 percentage points, according to national register data. In the Norwegian-born subgroup, the gap has increased by 2.4 percentage points, from 5.8 to 8.2. The goal of the study was to identify the demographic drivers of this development, using a quite simple, but original, decomposition approach. The components reflect changes in relative cohort sizes, whether the child has one native and one immigrant parent, whether the father was older than 45, and whether one of the parents already had a child, no longer lived in Norway at age 45, or was unidentified. It was found that the modestly increasing sex gap in childlessness among the Norwegian-born is largely linked to changes in cohort sizes, i.e. fertility trends. Changes in re-partnership have actually contributed weakly in the opposite direction: It has become more common especially among men to have the first child with a partner who already had a child, and thus not contribute to bringing also that person out of childlessness. The importance of the various components is different for immigrants, among whom the sex gap in childlessness has increased particularly much. This development may also reflect that especially male immigrants perhaps have children in the home country who are not included in the Norwegian register. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10680-021-09590-4.