Association between reproductive lifespan and lung function among postmenopausal women

Aging in females is associated with changes in respiratory modulation of sympathetic nerve activity and blood pressure

Sympathetic nerve activity (SNA) is tightly coupled with the respiratory cycle. In healthy human males, respiratory modulation of SNA does not change with age. However, it is unclear how this modulation is affected by age in females. We investigated whether respiratory sympathetic modulation is altered in healthy postmenopausal (PMF) versus premenopausal female (YF), and younger male (YM) adults, and determined its relationship to resting blood pressure. Muscle SNA (MSNA; microneurography), respiration (transducer belt), ECG, and continuous blood pressure were measured in 12 YF, 13 PMF, and 12 YM healthy volunteers. Respiratory modulation of MSNA was quantified during two phases of the respiratory cycle: mid-late expiration and inspiration/postinspiration. All groups showed respiratory modulation of MSNA (P < 0.0005). There was an interaction between the respiratory phase and group for MSNA [bursts/100 heartbeats (HB) (P = 0.004) and bursts/min (P = 0.029)], with smaller reductions in MSNA during inspiration observed in PMF versus the other groups. Respiratory modulation of blood pressure was also reduced in PMF versus YF (6 [2] vs. 12 [9] mmHg, P = 0.008) and YM (13 [13] mmHg, P = 0.001, median [interquartile range]). The magnitude of respiratory sympathetic modulation was related to resting blood pressure in PMF only, such that individuals with less modulation had greater resting blood pressure. The data indicate that aging in postmenopausal females is associated with less inspiratory inhibition of MSNA. This correlated with a higher resting blood pressure in PMF only. Thus, the reduced modulation of MSNA could contribute to the age-related rise in blood pressure that occurs in females.NEW & NOTEWORTHY The current study demonstrates that respiratory modulation of sympathetic nerve activity (SNA) is reduced in healthy postmenopausal (PMF) versus premenopausal females (YF). Furthermore, respiratory sympathetic modulation was negatively related to resting blood pressure in postmenopausal females, such that blood pressure was greater in individual with less modulation. Reduced respiratory sympathetic modulation may have implications for the autonomic control of blood pressure in aging postmenopausal females, by contributing to age-related sympathetic activation and reducing acute, respiratory-linked blood pressure variation.

Relationship between vitamin D levels and age of menopause and reproductive lifespan: Analysis based on the National health and nutrition examination survey (NHANES) 2001-2018

OBJECTIVES

To determine the association between serum vitamin D levels and age at menopause and reproductive lifespan in a group of US postmenopausal women.

STUDY DESIGN

Data from 6,326 postmenopausal US women in the National Health and Nutrition Examination Survey (NHANES) database 2001-2018 were obtained. Weighted multinomial logistic regression models were used to obtain odds ratios (OR) and 95% confidence intervals (CI). Statistical analyzes were performed using SAS (version 9.4; SAS Institute), and complex survey designs were considered.

RESULTS

Vitamin D deficiency was associated with a higher likelihood of early menopause (OR = 1.34, 95% CI: 1.15, 1.58; p = 0.008) and lower odds of late menopause (OR = 0.79, 95% CI: 0.52, 0.95) in the unadjusted model but not in the adjusted model. Lower vitamin D levels were associated with a higher risk of a shorter reproductive lifespan. The strongest association was seen in the first tertile of vitamin D deficiency (OR = 1.54; 95% CI: 1:29-1:83). After adjustment, the associations were somewhat weakened but remained statistically significant.

CONCLUSIONS

The results of this study suggest that vitamin D deficiency and inadequacy might be associated with earlier age at menopause. It may also reduce the reproductive lifespan in women. Given the cross-sectional nature of the NHANES dataset, these results should be interpreted with caution due to temporality bias. Menopausal age is a multifactorial phenomenon, and the identification of factors and their interactions should be evaluated in future studies.

Cumulative Endogenous Estrogen Exposure Is Associated With Postmenopausal Fracture Risk: The Women's Health Initiative Study

We aimed to evaluate the relationship between cumulative endogenous estrogen exposure and fracture risk in 150,682 postmenopausal women (aged 50 to 79 years at baseline) who participated in the Women's Health Initiative. We hypothesized that characteristics indicating lower cumulative endogenous estrogen exposure would be associated with increased fracture risk. We determined ages at menarche and menopause as well as history of irregular menses from baseline questionnaires and calculated years of endogenous estrogen exposure from ages at menarche and menopause. Incident clinical fractures were self-reported over an average 16.7 years of follow-up. We used multivariable proportional hazards models to assess the associations between the estrogen-related variables and incidence of any clinical fracture. In fully adjusted models, those with the fewest years of endogenous estrogen exposure (<30) had an 11% higher risk of developing central body fractures and a 9% higher risk of lower extremity fractures than women with 36 to 40 years of endogenous estrogen exposure (the reference category). In contrast, women with the most years of endogenous estrogen exposure (more than 45 years) had a 9% lower risk of lower extremity fractures than the reference category. Women with irregular (not monthly) menstrual cycles were 7% to 8% more likely to experience lower extremity fractures than women with regular monthly cycles. Our findings support the hypothesis that characteristics signifying lower cumulative endogenous estrogen exposure are associated with higher fracture risk. © 2022 American Society for Bone and Mineral Research (ASBMR).

Central Haemodynamics Are Associated With Pulmonary Function in Postmenopausal Women

PURPOSE

Increased arterial stiffness predicts cardiovascular disease, which is associated with deteriorated pulmonary function and worsened chronic obstructive pulmonary disease. The present study examined whether arterial function was associated with pulmonary function in postmenopausal women.

METHODS

This study evaluated 41 postmenopausal women (age range: 59-85 years). Arterial function was measured as central systolic blood pressure (cSBP), central pulse pressure (cPP), brachial systolic BP (bSBP), brachial diastolic BP (bDBP), brachial PP (bPP), brachial mean arterial pressure (bMAP) and the augmentation index (AIx). AIx was adjusted for a heart rate of 75 beats per minute (bpm) (AIx@75) and served as the index of arterial stiffness determined by the reflected wave at the central artery. Pulmonary function was measured as forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁) and the FEV₁/FVC ratio.

RESULTS

Univariate regression analysis demonstrated that cPP, bDBP and bPP were correlated with FVC and FEV₁ (p<0.05, respectively), while AI@75 was correlated with FVC, FEV₁ and FEV₁/FVC ratio (p<0.01, respectively). A stepwise multivariate regression analysis revealed that bDBP was independently associated with FVC (p=0.032), while AI@75 was independently associated with FVC, FEV₁ and FEV₁/FVC ratio (p=0.001, p=0.003 and p=0.017, respectively). The FVC, FEV₁ and FEV₁/FVC ratio were lower in participants with a high AIx versus with a low AIx (p=0.0001, p=0.001 and p=0.044, respectively).

CONCLUSION

These results suggest that increased AIx is associated with lower pulmonary function in postmenopausal women.