Associations of parity and age at first pregnancy with overall and cause-specific mortality in the Cancer Prevention Study II

Association between parity and female mortality: the mediative role of depressive symptoms

STUDY QUESTION

Is parity associated with all-cause and cause-specific mortality among women in a nationally representative cohort of the US population, and does depression mediate this association?

SUMMARY ANSWER

Nulliparous women have a higher risk of all-cause and cause-specific mortality, with depression partially mediating the relationship between parity and women's all-cause and cause-specific mortality.

WHAT IS KNOWN ALREADY

Parity, a significant state in reproductive life, has enduring implications for women's health. There is also a complex relationship between depression, a prevalent mental and emotional disorder, and female fertility. Previous studies have elucidated the relationships between parity and depression, both of which are associated with mortality. However, findings from studies examining parity and women's mortality have been inconsistent. Moreover, few studies have investigated whether the effect of parity on mortality is mediated by depression.

STUDY DESIGN, SIZE, DURATION

We conducted a cross-sectional study using data from seven cycles of the National Health and Nutrition Examination Survey (NHANES) spanning 2005-2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study cohort comprised adult women with available parity and survival follow-up data. Parity data were self-reported and sourced from the Reproductive Health Questionnaire. Depression scores were derived from the Patient Health Questionnaire 9, and cause-specific deaths were identified using the International Statistical Classification of Diseases, 10th Revision (ICD-10). Weighted multivariable Cox regression was applied to analyze the association between parity, depression, and mortality. Weighted linear regression was performed to examine the relationship between parity and depression. Mediation analyses were employed to determine whether and to what extent depression mediated the effect of parity on mortality.

MAIN RESULTS AND THE ROLE OF CHANCE

Our study ultimately encompassed 16 962 American women. Following multivariable adjustment, compared to nulliparous women, those with one to three live births exhibited a 17% and 33% reduction in all-cause and cancer mortality, respectively (all-cause mortality: HR = 0.83, 95% CI = 0.69-0.99, P = 0.040; cancer mortality: HR = 0.67, 95% CI = 0.45-0.99, P = 0.045). Women with more than four live births demonstrated lower all-cause mortality and mortality from other (not cancer or cardiovascular disease) diseases (all-cause mortality: HR = 0.73, 95% CI = 0.58-0.93, P = 0.011; other diseases mortality: HR = 0.66, 95% CI = 0.47-0.91, P = 0.013). No correlation was detected between parity and the risk of cardiovascular disease mortality among women. Furthermore, depression was found to partially mediate the impact of parity on all-cause mortality and mortality from other diseases in women.

LIMITATIONS, REASONS FOR CAUTION

Firstly, a single index of parity was used as an exposure factor, and other reproductive factors such as birth spacing, age at first birth, and mode of delivery were not taken into account. Secondly, despite accounting for important potentially confounders in our analysis, such as BMI, smoking status, and educational level, the influence of unmeasured confounders (e.g., social class, latent reproductive system diseases) on reproductive behavior or mortality cannot be dismissed. Thirdly, women's vulnerability to depression fluctuates across reproductive stages, and the effect of depression on female fertility varies over time. Due to data constraints, we were unable to obtain information on women's mental health status at different reproductive stages. Fourthly, due to the data accessibility limitations of NHANES, we were unable to specifically explore the relationship between parity and different specific types of cancer, a limitation that may obscure potential correlations. Additionally, despite our efforts to control for various confounding factors in subgroup analyses, the smaller sample sizes in some subgroups may limit the statistical power, affecting the ability to detect effects. Finally, studies exploring the association between parity and depression are cross-sectional designs, making it difficult to infer causality. These results should be interpreted with caution, and further research is warranted to corroborate our findings.

WIDER IMPLICATIONS OF THE FINDINGS

Our study underscores the elevated risk of all-cause and cause-specific mortality in nulliparous women and reveals that depression partially mediates the negative correlation between parity and women's all-cause mortality and mortality from other diseases. These results should be interpreted with caution, and further investigation is needed to support our findings.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Key Research and Development Program of China (2023YFC2705700), the Key Research & Developmental Program of Hubei Province (2022BCA042), and the Interdisciplinary Innovative Talents Foundation from Renmin Hospital of Wuhan University (JCRCWL-2022-001). The authors declare that they have no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Impact of preeclampsia on cardiovascular events: An analysis of the Generation Scotland: Scottish family health study

Preeclampsia is a recognised cause of an increased risk of major adverse cardiovascular events when compared to the background risk in women who did not have hypertensive disorders during pregnancy. The Generation Scotland: Scottish Family Health Study (GS:SFHS) is a population cohort of more than 20,000 members of the Scottish population. Using the Scottish Morbidity Records, we linked the women in the GS:SFHS cohort to validated maternity and inpatient admission data. This allowed us to robustly identify cardiovascular outcomes in the form of inpatient admission for cardiovascular events, We also aimed to explore the risk of pregnancy on future cardiovascular events, using data from nulliparous and parous women.In total, 9732 women were selected. 3693 women were nulliparous, and after study exclusion, 5253 women with 9583 pregnancies remained. Pregnancies from 1980 until the end of the study period of 1st of July 2013 were included. Cardiovascular events occurred in 9.0% of nulliparous women, 4.2% of women with pregnancies and in 7.6% of women with a history of preeclampsia. A total of 218 parous women experienced cardiovascular events, 25 in the preeclampsia group and 193 in the normotensive group.Survival analysis was undertaken, with index pregnancy taken as first pregnancy in normotensive controls and first preeclampsia pregnancy in cases. Endpoint of interest was admission to hospital with first cardiovascular event. After further exclusions a total of 169 cardiovascular events occurred in the normotensive pregnancy group and 20 in the preeclampsia group. Women with a history of preeclampsia were more likely to have cardiovascular events later in life than women with normotensive deliveries., This was statistically significantly different on Kaplan Meier survival analysis, (log rank Mantel-Cox p-value < 0.001). The women in our study were middle-aged, within 33 years of pregnancy, with a mean age of 53 years in the preeclampsia cardiovascular events group.Our study supports the urgent need for uniform guidelines and implementation to improve the health in women with this medical history. Increased awareness among the public of the cardiovascular risk associated with PE is vital to aid uptake of cardiovascular prevention programmes.

Beyond sex differences: short- and long-term effects of pregnancy on the brain

Growing attention has been directed to the inclusion of females in neuroscience studies, and to the importance of studying sex as a biological variable. However, how female-specific factors such as menopause and pregnancy, affect the brain remains understudied. In this review, we use pregnancy as a case in point of a female-unique experience that can alter neuroplasticity, neuroinflammation, and cognition. We examine studies in both humans and rodents indicating that pregnancy can modify neural function in the short term, as well as alter the trajectory of brain aging. Furthermore, we discuss the influence of maternal age, fetal sex, number of pregnancies, and presence of pregnancy complications on brain health outcomes. We conclude by encouraging the scientific community to prioritize researching female health by recognizing and including factors such as pregnancy history in research.

Association between gravidity and risk of metabolic syndrome: Results of Tabari cohort study

BACKGROUND AND AIMS

The purpose of the present study was to investigate the association of gravidity and age at first pregnancy with metabolic syndrome in a large-scale, population-based cohort study in Iran.

METHODS

The present secondary analysis was conducted on a subset of the population (5739 women with at least one pregnancy) enrolled in the Tabari cohort study. Reproductive history was collected using a structured questionnaire. The relationship of gravidity and age at first pregnancy with metabolic syndrome and its components was analyzed using the logistic regression model.

RESULTS

The results showed that after adjustment for confounding variables, the odds of having metabolic syndrome was not significantly associated with age at first pregnancy (P = 0.269) and gravidity (P = 0.504). However, there was an association between hypertension and age at first pregnancy (OR = 0.32, 95% CI = 0.12-0.82; P = 0.03). Additionally, waist circumference was also associated with gravidity (OR = 2.17, 95% CI = 1.37-3.35).

CONCLUSION

As the findings indicated, age at first pregnancy and gravidity were not associated with the odds of having metabolic syndrome. However, a relationship was found between first pregnancy at the age of >35 years and the decreased risk of hypertension. Gravidity was also found to be a dose-dependent risk factor for increased waist circumference.

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.

Infertility and mortality

BACKGROUND

Infertility affects 1 in 10 American reproductive-age women. The impact of this disease beyond the reproductive years is largely unknown.

OBJECTIVE

The objective of the study was to determine the association of infertility history with all-cause and cause-specific mortality.

STUDY DESIGN

This secondary analysis of a multicenter randomized clinical trial included 75,784 women (aged 55-74 years) prospectively enrolled in the Prostate, Lung, Colorectal, and Ovarian cancer-screening trial from 1992 through 2001 and followed up a minimum of 10 years for health-related outcomes and death (856,935 person-years). We examined the association of infertility history (inability to conceive for 1 year or greater) of all-cause and cause-specific mortality using disease risk score-adjusted Cox-proportional hazard regression models.

RESULTS

Infertile women had a 10% increased risk of death (from any cause) during the study period compared with the unexposed (adjusted hazard risk, 1.10, 95% confidence interval, 1.02-1.18, P = .010). This effect was predominantly noted in women at an otherwise low risk of mortality who had a 26% increased risk of death (adjusted hazard risk, 1.26, 95% confidence interval, 1.12-1.42, P < .001). No differences in cardiovascular or diabetic mortality were noted. The risk of cancer death at any time over the study period was increased by 23% in infertile women compared with the unexposed (adjusted hazard risk, 1.23, 95% confidence interval, 1.10-1.37, P < .001). This effect was predominantly noted in women at an otherwise low risk of cancer mortality who had a 47% increased risk of cancer death (adjusted hazard risk, 1.47, 95% confidence interval, 1.25-1.73, P < .001). While no differences are seen in the risk of death from endometrial or ovarian cancer, the risk of death from breast cancer was more than doubled in infertile women at an otherwise low risk of breast cancer death compared with the unexposed (adjusted hazard risk, 2.64, 95% confidence interval, 1.71-4.08, P < .001).

CONCLUSION

Infertility is a harbinger of future morbidity and mortality. Infertile women are at an increased risk of all-cause and cancer-related mortality. Consideration of infertility history in health care maintenance presents an opportunity for screening and early intervention for long-term health outcomes.

Female reproductive history in relation to chronic obstructive pulmonary disease and lung function in UK biobank: a prospective population-based cohort study

OBJECTIVES

Sex differences in respiratory physiology and predilection for developing chronic obstructive pulmonary disease (COPD) have been documented, suggesting that female sex hormones may influence pathogenesis. We investigated whether aspects of female reproductive health might play a role in risk of COPD among women.

DESIGN

Population-based prospective cohort study.

SETTING

UK Biobank recruited across 22 centres in the UK between 2006 to 2010.

PRIMARY AND SECONDARY OUTCOMES MEASURES

We examined a range of female reproductive health indicators in relation to risk of COPD-related hospitalisation/death (n=271 271) using Cox proportional hazards regression; and lung function (n=273 441) using linear regression.

RESULTS

Parity >3 was associated with greater risk of COPD-related hospitalisation/death (adjusted HR 1.45; 95% CI: 1.16 to 1.82) and lower forced expiratory volume at 1 second/forced vital capacity ratio (FEV1/FVC) (adjusted mean difference -0.06; 95% CI: -0.07 to 0.04). Any oral contraception use was associated with lower risk of COPD-related hospitalisation/death (adjusted HR 0.85; 95% CI: 0.74 to 0.97) and greater FEV1/FVC (adjusted mean difference 0.01; 95% CI: 0.003 to 0.03). Late menarche (age >15) and early menopause (age <47) were also associated with greater risk of COPD-related hospitalisation/death (but not lung function), while endometriosis was associated with greater FEV1/FVC (not COPD-related hospitalisation/death). Early menarche (age <12 years) was associated with lower FEV1/FVC (but not COPD hospitalisation/death). Associations with polycystic ovary syndrome (PCOS) or ovarian cysts, any hormone replacement therapy (HRT) use, hysterectomy-alone and both hysterectomy and bilateral oophorectomy were in opposing directions for COPD-related hospitalisation/death (greater risk) and FEV1/FVC (positive association).

CONCLUSIONS

Multiple female reproductive health indicators across the life course are associated with COPD-related hospitalisation/death and lung function. Further studies are necessary to understand the opposing associations of PCOS/ovarian cysts, HRT and hysterectomy with COPD and objective measures of airway obstruction.

Female reproductive factors and the likelihood of reaching the age of 90 years. The Netherlands Cohort Study

OBJECTIVES

The aim of this study was to prospectively assess the relationship between several reproductive factors in women and the likelihood of reaching the age of 90 years (achieving longevity).

STUDY DESIGN

For this study, data from the oldest birth cohort (1916-17) of the prospective Netherlands Cohort Study (NLCS) were used. These participants filled in a baseline questionnaire in 1986 (at age 68-70 years). Follow-up for vital status information until the age of 90 years (2006-07) was >99.9% complete.

MAIN OUTCOME MEASURES

Multivariable-adjusted Cox regression analyses with a fixed follow-up time were based on 2,697 women with complete exposure and co-variable data to calculate risk ratios (RR) of reaching age 90.

RESULTS

No associations were observed between the likelihood of reaching the age of 90 years, and age at menarche, age at menopause, parity, menstrual lifespan, and oral contraceptive use after adjustment for potential confounders. A later age at first childbirth pointed towards a higher chance of achieving longevity (age ≥30 vs. 20-24; RR,1.17; 95%CI,0.98-1.39). Ever-use of hormone replacement therapy (HRT) was significantly associated with a higher chance of achieving longevity compared with never HRT-users, but only in women who had had an early menopause (<50 years)(RR,1.32; 95% CI, 1.07-1.61).

CONCLUSION

Age at first childbirth, and ever-use of HRT in women with an early menopause (<50 years) were associated with the likelihood of reaching the age of 90 years.

The Association Between Parity and Subsequent Cardiovascular Disease in Women: The Atherosclerosis Risk in Communities Study

Background: Previous studies are inconclusive on the relationship between parity and cardiovascular disease (CVD), with few evaluating multiple cardiovascular outcomes. It is also unclear if any relationship between parity and CVD is independent of breastfeeding. We examined the associations between parity and cardiovascular outcomes, including breastfeeding adjustment. Materials and Methods: Data were from 8,583 White and African American women, 45-64 years of age, in the Atherosclerosis Risk in Communities Study. Coronary heart disease (CHD), myocardial infarction (MI), heart failure, and strokes were ascertained from 1987 to 2016 by annual interviews and hospital surveillance. Parity and breastfeeding were self-reported. Cox proportional hazards regression estimated hazard ratios (HR) for the association between parity and cardiovascular outcomes, adjusting for baseline sociodemographic, clinical and lifestyle factors, and breastfeeding. Results: Women reported no pregnancies (6.0%), or having 0 (1.6%), 1-2 (36.2%), 3-4 (36.4%), or 5+ (19.7%) live births. During 30 years follow-up, there were 1,352 CHDs, 843 MIs, 750 strokes, and 1,618 heart failure events. Compared with women with 1-2 prior births, those with prior pregnancies and no live births had greater incident CHD (HR = 1.64, 95% confidence interval 1.14-2.42) and heart failure risk (1.46, 1.04-2.05), after adjustment for baseline characteristics. Women with 5+ births had greater risk of CHD (1.29, 1.10-1.52) and hospitalized MI (1.38, 1.13-1.69), after adjustment for baseline characteristics and breastfeeding. Conclusions: In a diverse U.S. cohort, a history of 5+ live births is associated with CHD risk, specifically, MI, independent of breastfeeding. Having a prior pregnancy and no live birth is associated with greater CHD and heart failure risk.

Parity associated with telomere length among US reproductive age women

STUDY QUESTION

Is telomere length related to parity among a nationally representative sample of US reproductive age women?

SUMMARY ANSWER

History of live birth was associated with shorter telomere length.

WHAT IS KNOWN ALREADY

Shorter telomeres have been linked with a range of chronic health conditions and mortality and parity has been associated with health indicators. However, there is a lack of research on how parity relates to telomere length.

STUDY DESIGN, SIZE, DURATION

This nationally representative, cross-sectional study included 1954 women from the National Health and Nutrition Examination Survey, 1999-2002, the only survey period which includes measurement of telomere length.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women aged 20-44 were included. Parity, defined as number of previous live births, was ascertained by questionnaire. Leukocyte telomere length was measured by polymerase chain reaction and reported as a ratio in relation to standard reference DNA (T/S ratio). The relationship between leukocyte T/S ratio and parity was examined using survey weighted linear regression. Models were adjusted for race/ethnicity, age, BMI, income-to-poverty ratio, education, early age at menarche and smoking status.

MAIN RESULTS AND THE ROLE OF CHANCE

Among reproductive age women in the US, the adjusted mean leukocyte T/S ratio was 4.2% (95% CI: 0.9, 7.3) shorter in parous compared with nulliparous women. Parity was associated with 116 fewer base pairs (95% CI: 26, 204) on average, using estimated coefficients from the adjusted linear regression models and mean covariate values.

LIMITATIONS REASONS FOR CAUTION

This study was cross-sectional and therefore was unable to establish temporality. The dataset lacked information on social factors, stress and fertility status, which may help explain these findings. Only two previous studies have examined this question and our findings should be interpreted with caution.

WIDER IMPLICATIONS OF THE FINDINGS

These findings in a nationally representative sample of US reproductive age women suggest that history of live birth may be associated with accelerated cellular aging. The magnitude of the observed association was greater than that of the impact of smoking or obesity on telomere length, suggesting that parity may have an independent influence on cellular aging and warrant further study.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded in part by the Undergraduate Research Scholars Program at George Mason University. The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

NA.

Mechanisms of Sex Disparities in Cardiovascular Function and Remodeling

Epidemiological studies demonstrate disparities between men and women in cardiovascular disease prevalence, clinical symptoms, treatments, and outcomes. Enrollment of women in clinical trials is lower than men, and experimental studies investigating molecular mechanisms and efficacy of certain therapeutics in cardiovascular disease have been primarily conducted in male animals. These practices bias data interpretation and limit the implication of research findings in female clinical populations. This review will focus on the biological origins of sex differences in cardiovascular physiology, health, and disease, with an emphasis on the sex hormones, estrogen and testosterone. First, we will briefly discuss epidemiological evidence of sex disparities in cardiovascular disease prevalence and clinical manifestation. Second, we will describe studies suggesting sexual dimorphism in normal cardiovascular function from fetal life to older age. Third, we will summarize and critically discuss the current literature regarding the molecular mechanisms underlying the effects of estrogens and androgens on cardiac and vascular physiology and the contribution of these hormones to sex differences in cardiovascular disease. Fourth, we will present cardiovascular disease risk factors that are positively associated with the female sex, and thus, contributing to increased cardiovascular risk in women. We conclude that inclusion of both men and women in the investigation of the role of estrogens and androgens in cardiovascular physiology will advance our understanding of the mechanisms underlying sex differences in cardiovascular disease. In addition, investigating the role of sex-specific factors in the development of cardiovascular disease will reduce sex and gender disparities in the treatment and diagnosis of cardiovascular disease. © 2019 American Physiological Society. Compr Physiol 9:375-411, 2019.