Sex-Specific Reproductive Factors Augment Cardiovascular Disease Risk in Women: A Mendelian Randomization Study

Association of age at menarche, reproductive lifespan and age at menopause with the risk of atrial fibrillation: The HUNT study

BACKGROUND

Age at menarche, reproductive lifespan, and age at menopause are associated with several cardiovascular diseases, but their relationship with atrial fibrillation (AF) is uncertain.

METHODS

We linked information on all women who participated in the third survey of the population-based, longitudinal HUNT study in Norway with medical records from all local hospitals. A total of 14,632 women aged 60 or more were followed for validated incident AF. We retrieved age at menarche and age at menopause from the HUNT questionnaires. Reproductive lifespan was defined as the difference between age at menarche and age at menopause. We used Cox proportional hazards regression models to assess associations between AF and age at menarche, reproductive lifespan, and age at menopause.

RESULTS

During a median follow-up of 8.17 years (136,494 person-years), 1217 (8.3 %) participants developed AF. In multivariable-adjusted analyses, we observed no associations between early or late age at menarche and AF (hazard ratios (HRs): <12 years: 0.85 [95 % confidence interval (CI), 0.65-1.12]; ≥16 years: 0.99 [95 % CI, 0.80-1.24] compared to those who attained menarche at 13-14 years). The HR for a reproductive lifespan shorter than 30 years was 0.91 [95 % CI, 0.72-1.15] compared to 34-37 years. Likewise, there was no clear association between premature or early age at menopause and AF (HRs: <40 years: 1.21 [95 % CI, 0.83-1.75]; 40-44 years: 0.97 [95 % CI, 0.77-1.22] compared to 50-54 years).

CONCLUSIONS

In this population of women aged 60 years and over, the risk of AF was not associated with age at menarche, reproductive lifespan, or age at menopause.

Pregnancy, Reproductive Factors, and Female Heart Failure Risk and Outcomes

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of recent evidence on female-specific risk factors related to reproductive status or pregnancy.

RECENT FINDINGS

Pregnancy-related factors, including hypertensive disorders and gestational diabetes, increase the risk of heart failure in women, while breastfeeding and hormone therapy may offer protection. Hypertensive disorders of pregnancy, gestational diabetes, polycystic ovarian syndrome, placental abruption, younger maternal age at first live birth, younger maternal age at last live birth, number of stillbirths, number of pregnancies, onset of menstruation before 12 years of age, shorter reproductive age, ovariectomy, and prolonged absence of ovarian hormones may increase the risk of heart failure in women. Conversely, breastfeeding status and hormone therapy (for menopause or contraception) may serve as protective factors, while fertility treatments have no discernible effect on the risk of heart failure.

Survival costs and benefits of reproduction: A register-based study in 20th century Estonia

Patterns of individual variation in lifespan and senescence depend on the associations between parental survival and reproductive rates. We studied the associations between parity and survival among 579,271 Estonians born between 1905 and 1945 and in a cohort with a completed lifespan born in 1905-1927. For this cohort, selection for increased lifespan operated on both sexes, but it was stronger in men than in women. However, the median lifespan increased between the subsequent cohorts in women but stagnated in men. Selection for longer lifespan was caused by the below-average lifespan of individuals with no or single offspring. Despite a general positive selection for lifespan, survival costs of reproduction were also detected among a relatively small proportion of individuals with high parities, as mothers of two and fathers of two and three children had the highest median lifespans. Fathers of more than six children had better survival than fathers of few children in their reproductive age, but this association reversed after age 70. The reversal of this association between survival and parity at old age indicates that relative mortality risks between those with lower versus higher parities change across ages, as predicted by the antagonistic pleiotropy theory of aging.

The menopausal transition period and cardiovascular risk

The menopausal transition period spans, on average, 2-8 years before the final menstrual period and is associated with an increase in clinical and subclinical cardiovascular risk. In this Review, we discuss the metabolic and cardiovascular changes that occur during the menopausal transition period and the role of ovarian ageing, chronological ageing and other ageing-related risk factors in mediating these changes. Disentangling the relative contributions of chronological and reproductive ageing to cardiovascular risk is challenging, but data from longitudinal studies in women transitioning from premenopause to post-menopause have provided valuable insights. We also discuss evidence on how cardiovascular risk is altered by premature or early menopause, surgical menopause, and vasomotor and other menopausal symptoms. Whether targeted interventions can slow the progression of atherosclerosis and subclinical disease during the menopausal transition, thus delaying or preventing the onset of cardiovascular events, remains to be determined. Furthermore, we consider the recommended strategies for cardiovascular risk reduction in women undergoing menopausal transition using the framework of the American Heart Association's Life's Essential 8 key measures for improving and maintaining cardiovascular health, and discuss the cardiovascular risks and benefits of menopausal hormone therapy. Finally, we also discuss novel therapies that might benefit this population in reducing cardiovascular risk.

Reproductive milestones across the lifespan and cardiovascular disease risk in women

Cardiovascular disease (CVD) is the leading cause of death for women across the developed and developing world. Beyond traditional cardiovascular risk factors, a number of reproductive milestones have been recognized. The goal of this White Paper, issued by the International Menopause Society in conjunction with World Menopause Day 2023, is to highlight female reproductive milestones in terms of potential cardiovascular risk and to review recommendations for minimizing that risk. The primary milestones discussed relate to menstrual cyclicity, adverse pregnancy outcomes, breast cancer treatments and menopause. Each of these categories has a number of permutations that have been shown in observational studies to be associated with increased cardiovascular risks. In current clinical care, recognition of these reproductive milestones has been encouraged so patients can be informed and motivated to engage in primary prevention of CVD early in their life course rather than retrospectively later in life. Options for specifically targeted care with specialist teams are designed to enhance success with risk identification, screening and possible detection of CVD and, optimally, primary or secondary prevention of CVD. Promoting cardiovascular health of women has far-reaching effects for themselves, their families and their progeny. It is time to make women's cardiovascular health a priority.

The J shaped association of age at menarche and cardiovascular events: systematic review and meta-analysis

This study aimed to evaluate the association between age at menarche and cardiovascular (CV) events through a systematic review and meta-analysis of observational studies. A comprehensive literature search covering studies published from January 1, 2000, to October 31, 2023, was conducted in PubMed, MEDLINE, Embase, and Scopus. Twenty-nine observational studies involving 4,931,160 adult women aged 18 years or older were included. The meta-analysis revealed a J-shaped association between age at menarche and CV events. Individuals with menarche at 12-13 years exhibited the lowest risk, while those with younger (≤ 11 years) or older ages (14-15 years and ≥ 16 years) showed an increased risk. Notably, individuals with age at menarche of 16 years and older had the highest risk of CV events. The pooled odds of CV mortality in age at menarche categories 14-15 years and ≥ 16 years were 37% (OR: 1.37, 95% CI 1.14-1.64, I2: 76.9%) and 64% (OR: 1.64, 95% CI 1.20-2.24, I2: 87%) higher than referent age at menarche 12-13 years. No statistically significant difference was found in CV mortality risk between individuals with age at menarche ≤ 11 years and those with age at menarche 12-13 years. The ORs for coronary heart disease were significantly higher for age at menarche ≥ 16 years (35% increase), while no significant difference was found for age at menarche ≤ 11 years or 14-15 years compared to age at menarche 12-13 years. Regarding stroke, the ORs for age at menarche ≤ 11, 14-15, and ≥ 16 years were significantly higher (7%, 24%, and 94% increase, respectively) compared to age at menarche 12-13 years. Dose-response meta-analysis and one-stage random-effect cubic spline models confirmed the J-shaped risk pattern. Meta-regression indicated that age and BMI were not significant sources of heterogeneity. Sensitivity analyses and the absence of publication bias further supported the robustness of the findings. This study concludes that age at menarche is independently associated with CV events, with a J-shaped pattern. The findings underscore the significance of considering menarche age as an independent risk factor for CV events. Further research is warranted to validate these findings and explore potential underlying mechanisms.

The causal effect of reproductive factors on pelvic floor dysfunction: a Mendelian randomization study

BACKGROUND

Pelvic floor dysfunction (PFD) is an extremely widespread urogynecologic disorder, the prevalence of which increases with aging. PFD has severely affected women's quality of life and has been called a social cancer. While previous studies have identified risk factors such as vaginal delivery and obesity for PFD, other reproductive factors, including age at menarche (AAMA), have been largely overlooked. Therefore, we used a Mendelian randomization (MR) study for the first time to investigate the potential causal relationship between reproductive factors and PFD.

METHODS

We obtained summary statistics from genome-wide association studies (GWAS) for female genital prolapse (FGP), stress urinary incontinence (SUI), and five reproductive factors. Two-sample Mendelian randomization analysis (TSMR) was performed to explore the causal associations between these factors. The causal effects of reproductive factors on FGP and SUI were primarily estimated using the standard inverse variance weighting (IVW) method, with additional complementary and sensitivity analyses conducted using multiple approaches. A multivariate Mendelian randomization (MVMR) study was also conducted to adjust for pleiotropic effects and possible sources of selection bias and to identify independent exposure factors.

RESULTS

Our findings revealed that advanced age at first sexual intercourse (AFS) and age at first birth (AFB) exhibited negative causal effects on both FGP and SUI. AAMA showed negative causal effects solely on FGP, while age at last live birth (ALB) and age at menopause (AAMO) did not demonstrate any causal effect on either FGP or SUI. And the MVMR results showed that AFB and AFS had independent negative causal effects on FGP and SUI, respectively.

CONCLUSIONS

This study, for the first time, investigates the causal relationship between reproductive factors and PFD. The results suggested a causal relationship between some reproductive factors, such as AFB and AFS, and PFD, but there were significant differences between FGPand SUI. Therefore, future studies should explore the underlying mechanisms and develop preventive measures for reproductive factors to reduce the disease burden of PFD.

Causal Effects of Basal Metabolic Rate on Cardiovascular Disease: A Bidirectional Mendelian Randomization Study

BACKGROUND

Despite the health effects of basal metabolic rate (BMR), the causal effect of BMR on cardiovascular diseases (CVDs) remains undetermined. To elucidate the causal nature, Mendelian randomization (MR) analyses were performed.

METHODS AND RESULTS

Summary genome-wide association statistics regarding BMR and 5 CVDs were obtained from European databases. A 2-sample bidirectional MR was performed to assess the causal association between BMR and CVDs. The causal effects were estimated using inverse variance weighting. Simultaneously, multiple sensitivity analyses were performed to validate the robustness and reliability of the results. Our results indicated that genetically predicted BMR was significantly positively associated with the risk of heart failure (odds ratio, 1.53 [95% CI, 1.39-1.67]; P<0.001), atrial fibrillation and flutter (odds ratio, 2.12 [95% CI, 1.87-2.40]; P<0.001), and aortic aneurysm (odds ratio, 1.64 [95% CI, 1.41-1.92]; P<0.001). Genetically predicted BMR may not be causally associated with coronary artery disease and ischemic stroke risk. Furthermore, a significant causal effect of CVDs on BMR was not found in the reverse MR analysis. Multivariable MR was applied to further assess the direct effect of BMR on CVDs. Multivariable MR indicated that a high level of BMR still increased the risk of heart failure and atrial fibrillation and flutter after adjustment independent of possible confounders. However, the P value of aortic aneurysm was not significant.

CONCLUSIONS

The present study provides robust evidence that genetically predicted BMR is independently causally associated with heart failure and atrial fibrillation and flutter but not vice versa. These findings have implications for the prevention and treatment of CVDs in clinical practice.

Age at menarche, type 2 diabetes and cardiovascular disease complications in US women aged under 65 years: NHANES 1999-2018

Background

Diabetes and diabetes complications are on the rise in US adults aged <65 years, while onset of menarche at a younger age is also increasing. We examined the associations of age at menarche with type 2 diabetes among women aged <65 years and with cardiovascular disease (CVD) complications among women with diabetes.

Methods

Using the nationally representative cross-sectional National Health and Nutrition Examination Survey 1999-2018, women aged 20-65 years free of cancer were included in the current analysis. Diabetes was defined as a self-reported diabetes diagnosis. CVD was defined as coronary heart disease or stroke. Age at menarche was self-reported age of first menstruation and categorised into ≤10, 11, 12, 13, 14 and ≥15 years.

Results

Of 17 377 women included in the analysis, 1773 (10.2%) reported having type 2 diabetes. Earlier age at menarche was associated with type 2 diabetes compared with median age at menarche of 13 years, after adjustment for age, race/ethnicity, education, parity, menopause status and family history of diabetes, smoking status, physical activity, alcohol consumption and body mass index (p for trend=0.02). Among women with diabetes, earlier age at menarche was associated with stroke with similar adjustment (p for trend=0.03), but not with total CVD. Extremely early age at menarche (≤10 years) was significantly associated with stroke (adjusted OR 2.66 (95% CI 1.07 to 6.64)) among women aged <65 years with diabetes with similar adjustment.

Conclusions

Earlier age at menarche was associated with type 2 diabetes among young and middle-aged women in the USA and with stroke complications among these women living with diabetes.

Review of mendelian randomization studies on age at natural menopause

Menopause marks the end of the reproductive phase of life. Based on epidemiological studies, abnormal age at natural menopause (ANM) is thought to contribute to a number of adverse outcomes, such as osteoporosis, cardiovascular disease, and cancer. However, the causality of these associations remains unclear. A powerful epidemiological method known as Mendelian randomization (MR) can be used to clarify the causality between ANM and other diseases or traits. The present review describes MR studies that included ANM as an exposure, outcome and mediator. The findings of MR analyses on ANM have revealed that higher body mass index, poor educational level, early age at menarche, early age at first live birth, early age at first sexual intercourse, and autoimmune thyroid disease appear to be involved in early ANM etiology. The etiology of late ANM appears to be influenced by higher free thyroxine 4 and methylene tetrahydrofolate reductase gene mutations. Furthermore, early ANM has been found to be causally associated with an increased risk of osteoporosis, fracture, type 2 diabetes mellitus, glycosylated hemoglobin, and the homeostasis model of insulin resistance level. In addition, late ANM has been found to be causally associated with an increased systolic blood pressure, higher risk of breast cancer, endometrial cancer, endometrioid ovarian carcinoma, lung cancer, longevity, airflow obstruction, and lower risk of Parkinson's disease. ANM is also a mediator for breast cancer caused by birth weight and childhood body size. However, due to the different instrumental variables used, some results of studies are inconsistent. Future studies with more valid genetic variants are needed for traits with discrepancies between MRs or between MR and other types of epidemiological studies.

Epidemiologic trends and risk factors associated with the decline in mortality from coronary heart disease in the United States, 1990-2019

BACKGROUND

Despite the decline in the rate of coronary heart disease (CHD) mortality, it is unknown how the 3 strong and modifiable risk factors - alcohol, smoking, and obesity -have impacted these trends. We examine changes in CHD mortality rates in the United States and estimate the preventable fraction of CHD deaths by eliminating CHD risk factors.

METHODS

We performed a sequential time-series analysis to examine mortality trends among females and males aged 25 to 84 years in the United States, 1990-2019, with CHD recorded as the underlying cause of death. We also examined mortality rates from chronic ischemic heart disease (IHD), acute myocardial infarction (AMI), and atherosclerotic heart disease (AHD). All underlying causes of CHD deaths were classified based on the International Classification of Disease 9th and 10th revisions. We estimated the preventable fraction of CHD deaths attributable to alcohol, smoking, and high body-mass index (BMI) through the Global Burden of Disease.

RESULTS

Among females (3,452,043 CHD deaths; mean [standard deviation, SD] age 49.3 [15.7] years), the age-standardized CHD mortality rate declined from 210.5 in 1990 to 66.8 per 100,000 in 2019 (annual change -4.04%, 95% CI -4.05, -4.03; incidence rate ratio [IRR] 0.32, 95% CI, 0.41, 0.43). Among males (5,572,629 CHD deaths; mean [SD] age 47.9 [15.1] years), the age-standardized CHD mortality rate declined from 442.4 to 156.7 per 100,000 (annual change -3.74%, 95% CI, -3.75, -3.74; IRR 0.36, 95% CI, 0.35, 0.37). A slowing of the decline in CHD mortality rates among younger cohorts was evident. Correction for unmeasured confounders through a quantitative bias analysis slightly attenuated the decline. Half of all CHD deaths could have been prevented with the elimination of smoking, alcohol, and obesity, including 1,726,022 female and 2,897,767 male CHD deaths between 1990 and 2019.

CONCLUSIONS

The decline in CHD mortality is slowing among younger cohorts. The complex dynamics of risk factors appear to shape mortality rates, underscoring the importance of targeted strategies to reduce modifiable risk factors that contribute to CHD mortality.