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

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.

Pregnancy History at 40 Years of Age as a Marker of Cardiovascular Risk

BACKGROUND

Individual pregnancy complications are associated with increased maternal risk of cardiovascular disease. We assessed the link between a woman's total pregnancy history at 40 years of age and her relative risk of dying from atherosclerotic cardiovascular disease (ASCVD).

METHODS AND RESULTS

This population-based prospective study combined several Norwegian registries covering the period 1967 to 2020. We identified 854 442 women born after 1944 or registered with a pregnancy in 1967 or later, and surviving to 40 years of age. The main outcome was the time to ASCVD mortality through age 69 years. The exposure was a woman's number of recorded pregnancies (0, 1, 2, 3, or 4) and the number of those with complications (preterm delivery <35 gestational weeks, preeclampsia, placental abruption, perinatal death, and term or near-term birth weight <2700 g). Cox models provided estimates of hazard ratios across exposure categories. The group with the lowest ASCVD mortality was that with 3 pregnancies and no complications, which served as the reference group. Among women reaching 40 years of age, risk of ASCVD mortality through 69 years of age increased with the number of complicated pregnancies in a strong dose-response fashion, reaching 23-fold increased risk (95% CI, 10-51) for women with 4 complicated pregnancies. Based on pregnancy history alone, 19% of women at 40 years of age (including nulliparous women) had an increased ASCVD mortality risk in the range of 2.5- to 5-fold.

CONCLUSIONS

Pregnancy history at 40 years of age is strongly associated with ASCVD mortality. Further research should explore how much pregnancy history at 40 years of age adds to established cardiovascular disease risk factors in predicting cardiovascular disease mortality.

Heterogeneity in the risk of cardiovascular disease mortality after the hypertensive disorders of pregnancy across mothers' lifetime reproductive history

BACKGROUND

Prior studies on maternal cardiovascular disease (CVD) mortality and hypertensive disorders of pregnancy (HDP) have focused only on a woman's first birth and have not accounted for successive affected pregnancies.

OBJECTIVES

The objective of this study is to identify mothers' risk of CVD mortality considering lifetime reproductive history.

METHODS

We used data from the Medical Birth Registry of Norway, the Norwegian Cause of Death Registry, and the Norwegian National Population Register to identify all mothers who gave birth from 1967 to 2020. Our outcome was mothers' CVD death before age 70. The primary exposure was the lifetime history of HDP. The secondary exposure was the order of HDP and gestational age at delivery of pregnancies with HDP. We used Cox regression models to estimate hazard ratio (HR) and 95% confidence interval (CI), adjusting for education, mother's age, and year of last birth. These models were stratified by the lifetime number of births.

RESULTS

Among 987,378 mothers, 86,294 had HDP in at least one birth. The highest CVD mortality, relative to mothers without HDP, was among those with a pre-term HDP in their first two births, although this represented 1.0% of mothers with HDP (HR 5.12, 95% CI 2.66, 9.86). Multiparous mothers with term HDP in their first birth only had no increased risk of CVD relative to mothers without HDP (36.9% of all mothers with HDP; HR 1.12, 95% CI 0.95, 1.32). All other mothers with HDP had a 1.5- to 4-fold increased risk of CVD mortality.

CONCLUSIONS

This study identified heterogeneity in the risk of CVD mortality among mothers with a history of HDP. A third of these mothers are not at higher risk compared to women without HDP, while some less common patterns of HDP history are associated with severe risk of CVD mortality.

The contribution of parity to ethnic differences in mothers' body mass index in the Netherlands: A Blinder-Oaxaca decomposition approach

Women of Turkish and Moroccan origin in the Netherlands are relatively likely to have an unhealthy bodyweight. This study sheds light on how ethnic differences in parity, i.e., the number of times a female carried pregnancies to a viable gestational age, contribute to body mass index (BMI) differences between Turkish-born and Moroccan-born mothers aged 35 + and their native Dutch counterparts. We applied a Blinder-Oaxaca decomposition approach to pooled data from four migrant surveys based on national probability samples (n = 2,532). Unlike conventional mediation analyses, the Blinder-Oaxaca approach recognizes that the association between parity and bodyweight may vary across different groups. Our results indicated that Turkish-born and Moroccan-born mothers in the Netherlands had more children and a higher BMI than native Dutch mothers. Regression analyses moreover showed that the parity-BMI gradient was steeper for Turkish-born mothers than for native Dutch mothers. Decomposition using the Blinder-Oaxaca approach indicated that the higher number of children of Turkish-born and Moroccan-born mothers compared to native Dutch mothers contributed substantially to the higher mean BMI in the former groups. The steeper parity-BMI gradient in Turkish-born mothers further amplified the contribution of parity to the higher mean BMI of Turkish-born mothers as compared to native Dutch mothers. Future research is needed to assess to which extent the steep parity-BMI gradient in Turkish-born mothers can be explained by relatively strong barriers to a healthy lifestyle that Turkish-born mothers of a larger number of children may face due to a relatively strongly gendered division of household and childrearing tasks.

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.

Parity and hypertension risk in couples: does number of parity matter: findings from Tehran Lipid and Glucose Study

BACKGROUND AND AIMS

As reported, hypertension (HTN) plays a leading role in explaining mortality worldwide, but it still has many confounding factors. This study explored whether the number of parity and age matters for HTN among couples from the Tehran Lipid and Glucose Study (TLGS).

METHODS

This study was conducted on 2851 couples from TLGS. All the variables were collected based on the standard protocol. The participants were categorized into four and five categories according to the number of parity (childless, one, two, three, or more parities) and age (18-30y, 30-40y, 40-50y, 50-60y, and 60-70y), respectively. Spline regression models via log link function for the binary outcome and linear link function for continuous outcomes were applied to evaluate the effect of interaction term age and parity categories on the desired outcome.

RESULTS

Among the total of 2851 pairs, 2.3% had no child, 9.5% had 1 child, 38.4% had 2 children, and 49.8% had ≥ 3 children. The adjusted risk (95% CI) of HTN in females aged 40-50y with 1 child, 2 and ≥ 3 children compared to no child were 1.14(1.04, 1.26), 1.05(1.01, 1.10), 1.12(1.07, 1.17), respectively (p < 0.05). Moreover, in those aged 50-60y with 2 and ≥ 3 children, the risk of HTN significantly increased by 4%. In females aged 60-70y with ≥ 3 children compared to those without children, the risk of HTN increased by 2%. For males aged 30-40y with 2 children compared to the no child group, the adjusted risk of HTN increased by 17%, while for those with ≥ 3 children in the same age group, this risk significantly decreased by 13%. Moreover, in males aged 30-40y with 2 children, risk ratio of HTN increased by 17%, but in males with ≥ 3 children, it decreased by 13% and in those in the same groups but aged 40-50y the risk increased by 6% and 11%, respectively.

CONCLUSION

Our findings suggest that gender, childlessness, having one child, and multi-parity had different impacts on HTN. Further research is needed to confirm our findings.

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.

Markers of Cardiovascular Risk Associated with Pregnancy

PURPOSE OF REVIEW

The purpose of the review is to summarize the unique cardiovascular disease (CVD) risk factors encountered during pregnancy and to provide the reader with a framework for acquiring a comprehensive obstetric history during the cardiovascular (CV) assessment of women.

RECENT FINDINGS

Individuals with a history of pregnancies complicated by hypertensive disorders of pregnancy (HDP), gestational diabetes (GDM), preterm delivery, low birth weight, and fetal growth restriction during pregnancy are at a higher risk of developing short- and long-term CV complications compared to those without adverse pregnancy outcomes (APOs). Women with a history of APOs can be at increased risk of CVD even after achieving normoglycemia and normal blood pressure control postpartum. Risk assessment and stratification in women must account for these APOs as recommended by the 2019 American College of Cardiology (ACC)/American Heart Association (AHA) guideline on the primary prevention of CVD. Early recognition, monitoring, and treatment of APOs are key to limiting CVD complications late in maternal life. Recognition of APOs as female-specific cardiovascular risk factors is critical for risk stratification for women and birthing persons. Further research is needed to understand the complex interplay between genetics, environmental, behavioral, and maternal vascular health, and the association between APOs and CVD risk.

Fertility Histories and Heart Disease in Later Life in China

Purpose

Based on life course theories, health among older people is driven by a continuous and cumulative process that develops over the life course. To better understand the aging process, it is important to assess associations between parity and heart disease in older people of China.

Method

The associations between heart disease prevalence and number of births, number of boys or girls ever born were evaluated among 5,990 samples (mean age 64.1 years) using the Probit regression model based on the data from China Health and Retirement Longitudinal Study (CHARLS) conducted in 2013 and 2018. The model was adjusted only for rural or urban residents, and multivariate regression models were run separately by gender.

Results

Our results showed that more than three children or more than two boys ever born were associated with a higher risk of heart disease. However, the number of girls ever born had no significant effect on heart disease in the elderly. We further analyzed the group difference between urban and rural residents using the regression model. More than three children or more than two boys ever born were associated with a high risk of heart disease in rural areas. Compared to urban residents, rural residents were more likely to be suffering from heart disease due to high parity. When considering the digender difference the paper found that more than three children ever born were associated with a high risk of heart disease in the female group. Late age at the time of giving birth for the first time was associated with a poorer risk level of heart disease in the rural residents, because the phenomenon of early childbearing was serious in the rural residents. But after considering the impact on the physical health of using chronic diseases, the first birth and the last birth both increased the risk of heart disease.

Conclusions

Some policy implications were being put forward. Firstly, parents who were ready to give birth should be aware of the possible health loss of high parity. Postpartum nutrition supplements and chronic disease prevention were suggested to prevent heart disease in later life. Secondly, the elderly in rural areas should pay more attention to heart diseases. Participating in more daily exercise and physical examinations was a good choice to reduce the risk of heart disease. Thirdly, women who give birth prematurely have a higher risk of CVD. Based on our results, age at entry to parenthood was closely related to the risk of heart disease in later life.

The causal effect of number of children on later-life overweight and obesity in parous women. An instrumental variable study

Many older women in Europe are overweight or obese. One of the factors linked to overweight and obesity among older women is childbearing. However, results of observational studies on the association between women’s number of children and excess weight should be interpreted with caution, because they may be prone to bias due to residual confounders or reverse causation. We use data of women aged 50 and older with at least two births from seven waves the Survey of Health, Ageing and Retirement in Europe (n = 113,932) collected between 2004 and 2020. We adopt an instrumental variable approach that exploits the well-established preference for mixed-sex offspring to estimate the causal effect of number of children on older parous women’s body mass index (BMI) and their risk of overweight (BMI >= 25 kg/m2) and obesity (BMI >= 30 kg/m2). The instrumental variable models provided evidence for a causal positive effect of having 3 + children as opposed to 2 children on mothers’ body mass index, overweight (BMI >= 25 kg/m2) risk and obesity (BMI >= 30 kg/m2) risk. Predicted BMI was 1.8 kg/m2 higher for mothers with 3 + children than for mothers with 2 children, and their predicted probability of overweight and obesity was 18.3 and 8.6 percentage points higher, respectively. Results remained virtually unchanged after adjusting for age, educational attainment, country and wave of data collection.

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.

Gravidity, parity, blood pressure and mortality among women in Bangladesh from the HEALS cohort

OBJECTIVES

Despite a hypothesised connection of reproductive history with hypertension and mortality, the nature of this association is poorly characterised. We evaluated the association of parity and gravidity with blood pressure, hypertension and all-cause mortality.

DESIGN

Prospective cohort study.

SETTING

Health Effects of Arsenic Longitudinal Study cohort in rural Bangladesh.

PARTICIPANTS

There were 21 634 Bangladeshi women recruited in 2000-2002, 2006-2008 and 2010-2014 included in the present analysis.

METHODS

Reproductive history was ascertained through an interviewer-administered questionnaire at the baseline visit. Blood pressure was measured by a trained study physician following a standard protocol at the baseline visit. Vital status was ascertained at the biennial follow-up of study participants through June 2017. Linear and logistic regression models estimated the relationship between parity and gravidity with blood pressure and hypertension, respectively. Cox proportional hazards models estimated the relationship with all-cause mortality only among women aged >45 years.

RESULTS

Diastolic blood pressure was lowest in women with parity one (reference) and elevated in nulliparous women (adjusted % change=3.12; 95% CI 1.93 to 4.33) and women with parity >2 (adjusted % change=1.71; 95% CI 1.12 to 2.31). The associations with nulliparity were stronger for women aged >45 years. Similar association patterns were observed with hypertension. Further, in nulliparous women aged >45 years, 265 deaths (6.6%) were ascertained during the follow-up period (median follow-up time=8 years), and we observed suggestive elevated risks of all-cause mortality (adjusted HR 3.83; 95% CI 0.74 to 19.78). The relationships between reproductive history, blood pressure, hypertension and mortality were similar when modelling reproductive history as gravidity rather than parity.

CONCLUSIONS

For women in rural Bangladesh, nulliparity and nulligravidity appear to be associated with higher blood pressure and subsequent elevated risk of mortality.