Optimising health after early menopause.

The typical age at menopause is 50-51 years in high-income countries. However, early menopause is common, with around 8% of women in high-income countries and 12% of women globally experiencing menopause between the ages of 40 years and 44 years. Menopause before age 40 years (premature ovarian insufficiency) affects an additional 2-4% of women. Both early menopause and premature ovarian insufficiency can herald an increased risk of chronic disease, including osteoporosis and cardiovascular disease. People who enter menopause at younger ages might also experience distress and feel less supported than those who reach menopause at the average age. Clinical practice guidelines are available for the diagnosis and management of premature ovarian insufficiency, but there is a gap in clinical guidance for early menopause. We argue that instead of distinct age thresholds being applied, early menopause should be seen on a spectrum between premature ovarian insufficiency and menopause at the average age. This Series paper presents evidence for the short-term and long-term consequences of early menopause. We offer a practical framework for clinicians to guide diagnosis and management of early menopause, which considers the nature and severity of symptoms, age and medical history, and the individual's wishes and priorities to optimise their quality of life and short-term and long-term health. We conclude with recommendations for future research to address key gaps in the current evidence.

Female reproductive histories and the risk of chronic obstructive pulmonary disease.

BACKGROUND: Female reproductive factors may influence the development of chronic obstructive pulmonary disease (COPD) through the female hormonal environment, but studies on this topic are limited. This study aimed to assess whether age at menarche, number of children, infertility, miscarriage, stillbirth and age at natural menopause were associated with the risk of COPD. METHODS: Women from three cohorts with data on reproductive factors, COPD and covariates were included. Cause specific Cox regression models were adjusted for birth year, race, educational level, body mass index and pack years of smoking, stratified by asthma, and incorporating interaction between birth year and time. Between cohort differences and within cohort correlations were taken into account. RESULTS: Overall, 2 83 070 women were included and 10 737 (3.8%) developed COPD after a median follow-up of 11 (IQR 10-12) years. Analyses revealed a U shaped association between age at menarche and COPD (≤11 vs 13: HR 1.17, 95% CI 1.11 to 1.23; ≥16 vs 13: HR 1.24, 95% CI 1.21 to 1.27). Women with three or more children (3 vs 2: HR 1.14, 95% CI 1.12 to 1.17; ≥4 vs 2: HR 1.34, 95% CI 1.28 to 1.40), multiple miscarriages (2 vs 0: HR 1.28, 95% CI 1.24 to 1.32; ≥3 vs 0: HR 1.36, 95% CI 1.30 to 1.43) or stillbirth (1 vs 0: HR 1.38, 95% CI 1.25 to 1.53; ≥2 vs 0: HR 1.67, 95% CI 1.32 to 2.10) were at a higher risk of COPD. Among postmenopausal women, earlier age at natural menopause was associated with an increased risk of COPD (<40 vs 50-51: HR 1.69, 95% CI 1.63 to 1.75; 40-44 vs 50-51: HR 1.42, 95% CI 1.38 to 1.47). CONCLUSIONS: Multiple female reproductive factors, including age at menarche, number of children, miscarriage, stillbirth, and age at natural menopause were associated with the risk of COPD.

Association of infertility and recurrent pregnancy loss with the risk of dementia.

Emerging evidence has shown the association between female reproductive histories (e.g., menarche age, parity, premature and early menopause) and the risk of dementia. However, little attention has been given to infertility and pregnancy loss. To examine the associations of infertility, recurrent miscarriages, and stillbirth with the risk of dementia, this study used data from four cohorts in the International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events. Women with data on at least one of the reproductive exposures of interest, dementia, and all covariates were included. Histories of infertility, miscarriage, and stillbirth were self-reported. Dementia (including Alzheimer's disease) was identified through surveys, aged care, pharmaceutical, hospital, and death registry data. Cause-specific Cox regression models were used to estimate the hazard ratios of dementia, accounting for well-established risk factors of dementia, study variability, and within-study correlation. Overall, 291,055 women were included at a median (interquartile range) age of 55.0 (47.0-62.0) at baseline. During the median (interquartile range) follow-up period of 13.0 (12.0-14.0) years, 3334 (1.2%) women developed dementia. Compared to women without stillbirth, a history of recurrent stillbirths (≥ 2) was associated with 64% higher risk of dementia (adjusted hazard ratio = 1.64, 95% confidence interval: 1.46-1.85). Compared to women without miscarriage, women with recurrent miscarriages (≥ 3) were at 22% higher risk of dementia (adjusted hazard ratio = 1.22, 95% confidence interval: 1.19-1.25). These findings suggest that recurrent stillbirths is a risk factor for dementia and may need to be considered in risk assessment of dementia in women.

Is there a link between infertility, miscarriage, stillbirth, and premature or early menopause? Results from pooled analyses of 9 cohort studies.

BACKGROUND: Some reproductive factors (such as age at menarche and parity) have been shown to be associated with age at natural menopause, but there has been little quantitative analysis of the association between infertility, miscarriage, stillbirth, and premature (<40 years) or early menopause (40-44 years). In addition, it has been unknown whether the association differs between Asian and non-Asian women, although the age at natural menopause is younger among Asian women. OBJECTIVE: This study aimed to investigate the association of infertility, miscarriage, and stillbirth with age at natural menopause, and whether the association differed by race (Asian and non-Asian). STUDY DESIGN: This was a pooled individual participant data analysis from 9 observational studies contributing to the InterLACE consortium. Naturally postmenopausal women with data on at least 1 of the reproductive factors (ie, infertility, miscarriage, and stillbirth), age at menopause, and confounders (ie, race, education level, age at menarche, body mass index, and smoking status) were included. A multinomial logistic regression model was used to estimate relative risk ratios and 95% confidence intervals for the association of infertility, miscarriage, and stillbirth with premature or early menopause, adjusting for confounders. Between-study difference and within-study correlation were taken into account by including study as a fixed effect and indicating study as a cluster variable. We also examined the association with number of miscarriages (0, 1, 2, ≥3) and stillbirths (0, 1, ≥2), and tested whether the strength of association differed between Asian and non-Asian women. RESULTS: A total of 303,594 postmenopausal women were included. Their median age at natural menopause was 50.0 years (interquartile range, 47.0-52.0). The percentages of women with premature and early menopause were 2.1% and 8.4%, respectively. The relative risk ratios (95% confidence intervals) of premature and early menopause were 2.72 (1.77-4.17) and 1.42 (1.15-1.74) for women with infertility; 1.31 (1.08-1.59) and 1.37 (1.14-1.65) for women with recurrent miscarriages; and 1.54 (1.52-1.56) and 1.39 (1.35-1.43) for women with recurrent stillbirths. Asian women with infertility, recurrent miscarriages (≥3), or recurrent stillbirths (≥2) had higher risk of premature and early menopause compared with non-Asian women with the same reproductive history. CONCLUSION: Histories of infertility and recurrent miscarriages and stillbirths were associated with higher risk of premature and early menopause, and the associations differed by race, with stronger associations for Asian women with such reproductive history.

Infertility, Miscarriage, Stillbirth, and the Risk of Stroke Among Women: A Systematic Review and Meta-Analysis.

BACKGROUND AND PURPOSE: Stroke is one of the leading causes of mortality, and women are impacted more from stroke than men in terms of their absolute number and in having worse outcomes. A growing number of studies have explored the association between pregnancy complications, pregnancy outcomes, and stroke. Limited studies, however, have investigated links involving infertility, miscarriage, and stillbirth, which could plausibly be associated via a background of endocrine conditions, endothelial dysfunction, and chronic systematic inflammation. This review aims to summarize current evidence and provide up-to-date information on the associations of infertility, miscarriage, and stillbirth, with stroke incidence. METHODS: A comprehensive literature search was conducted for cohort and case-control studies on associations between infertility, miscarriage, stillbirth, and stroke up to September 26, 2020. Seven databases were searched: PubMed, Embase, Cochrane, CINIHL, PsyclNFO, Wanfang, and CNKI. Random-effects models were used to estimate the pooled hazard ratios (HRs) and 95% CIs. RESULTS: Sixteen cohort studies and 2 case-control studies enrolling 7 808 521 women were included in this meta-analysis. Women who had experienced miscarriage or stillbirth were at higher risk of stroke (miscarriage: HR, 1.07 [95% CI, 1.00-1.14]; stillbirth: HR, 1.38 [95% CI, 1.11-1.71]) than other women. The HRs of stroke for each additional miscarriage and stillbirth were 1.13 (95% CI, 0.96-1.33) and 1.25 (95% CI, 1.06-1.49), respectively. In subgroup analysis, increased risk of stroke was associated with repeated miscarriages and stillbirths (miscarriage ≥3: HR, 1.42 [95% CI, 1.05-1.90]; stillbirth ≥2: HR, 1.14 [95% CI, 1.04-1.26]). Associations between infertility and stroke were inconsistent and inconclusive (HR, 1.07 [95% CI, 0.87-1.32]). CONCLUSIONS: Miscarriage and stillbirth are associated with increased risk of stroke among women, which could be used as a contributing risk factor to help identify women at higher risk of stroke.

Menopause, hysterectomy, menopausal hormone therapy and cause-specific mortality: cohort study of UK Biobank participants.

STUDY QUESTION: What is the association between menopausal hormone therapy (MHT) and cause-specific mortality? SUMMARY ANSWER: Self-reported MHT use following early natural menopause, surgical menopause or premenopausal hysterectomy is associated with a lower risk of breast cancer mortality and is not consistently associated with the risk of mortality from cardiovascular disease or other causes. WHAT IS KNOWN ALREADY: Evidence from the Women's Health Initiative randomized controlled trials showed that the use of estrogen alone is not associated with the risk of cardiovascular mortality and is associated with a lower risk of breast cancer mortality, but evidence from the Million Women Study showed that use of estrogen alone is associated with a higher risk of breast cancer mortality. STUDY DESIGN, SIZE, DURATION: Cohort study (the UK Biobank), 178 379 women, recruited in 2006-2010. PARTICIPANTS/MATERIALS, SETTING, METHODS: Postmenopausal women who had reported age at menopause (natural or surgical) or hysterectomy, and information on MHT and cause-specific mortality. Age at natural menopause, age at surgical menopause, age at hysterectomy and MHT were exposures of interest. Natural menopause was defined as spontaneous cessation of menstruation for 12 months with no previous hysterectomy or oophorectomy. Surgical menopause was defined as the removal of both ovaries prior to natural menopause. Hysterectomy was defined as removal of the uterus before natural menopause without bilateral oophorectomy. The study outcome was cause-specific mortality. MAIN RESULTS AND THE ROLE OF CHANCE: Among the 178 379 women included, 136 790 had natural menopause, 17 569 had surgical menopause and 24 020 had hysterectomy alone. Compared with women with natural menopause at the age of 50-52 years, women with natural menopause before 40 years (hazard ratio (HR): 2.38, 95% CI: 1.64, 3.45) or hysterectomy before 40 years (HR: 1.60, 95% CI: 1.23, 2.07) had a higher risk of cardiovascular mortality but not cancer mortality. MHT use was associated with a lower risk of breast cancer mortality following surgical menopause before 45 years (HR: 0.17, 95% CI: 0.08, 0.36), at 45-49 years (HR: 0.15, 95% CI: 0.07, 0.35) or at ≥50 years (HR: 0.28, 95% CI: 0.13, 0.63), and the association between MHT use and the risk of breast cancer mortality did not differ by MHT use duration (<6 or 6-20 years). MHT use was also associated with a lower risk of breast cancer mortality following natural menopause before 45 years (HR: 0.59, 95% CI: 0.36, 0.95) or hysterectomy before 45 years (HR: 0.49, 95% CI: 0.32, 0.74). LIMITATIONS, REASONS FOR CAUTION: Self-reported data on age at natural menopause, age at surgical menopause, age at hysterectomy and MHT. WIDER IMPLICATIONS OF THE FINDINGS: The current international guidelines recommend women with early menopause to use MHT until the average age at menopause. Our findings support this recommendation. STUDY FUNDING/COMPETING INTEREST(S): This project is funded by the Australian National Health and Medical Research Council (NHMRC) (grant numbers APP1027196 and APP1153420). G.D.M. is supported by NHMRC Principal Research Fellowship (APP1121844), and M.H. is supported by an NHMRC Investigator Grant (APP1193838). There are no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Type of menopause, age of menopause and variations in the risk of incident cardiovascular disease: pooled analysis of individual data from 10 international studies.

STUDY QUESTION: How does the risk of cardiovascular disease (CVD) vary with type and age of menopause? SUMMARY ANSWER: Earlier surgical menopause (e.g. <45 years) poses additional increased risk of incident CVD events, compared to women with natural menopause at the same age, and HRT use reduced the risk of CVD in women with early surgical menopause. WHAT IS KNOWN ALREADY: Earlier age at menopause has been linked to an increased risk of CVD mortality and all-cause mortality, but the extent that this risk of CVD varies by type of menopause and the role of postmenopausal HRT use in reducing this risk is unclear. STUDY DESIGN, SIZE, DURATION: Pooled individual-level data of 203 767 postmenopausal women from 10 observational studies that contribute to the International collaboration for a Life course Approach to reproductive health and Chronic disease Events (InterLACE) consortium were included in the analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: Postmenopausal women who had reported menopause (type and age of menopause) and information on non-fatal CVD events were included. Type of menopause (natural menopause and surgical menopause) and age at menopause (categorised as <35, 35-39, 40-44, 45-49, 50-54 and ≥55 years) were exposures of interest. Natural menopause was defined as absence of menstruation over a period of 12 months (no hysterectomy and/or oophorectomy) and surgical menopause as removal of both ovaries. The study outcome was the first non-fatal CVD (defined as either incident coronary heart disease (CHD) or stroke) event ascertained from hospital medical records or self-reported. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% CI for non-fatal CVD events associated with natural menopause and surgical menopause. MAIN RESULTS AND THE ROLE OF CHANCE: Compared with natural menopause, surgical menopause was associated with over 20% higher risk of CVD (HR 1.22, 95% CI 1.16-1.28). After the stratified analysis by age at menopause, a graded relationship for incident CVD was observed with lower age at menopause in both types of natural and surgical menopause. There was also a significant interaction between type of menopause and age at menopause (P < 0.001). Compared with natural menopause at 50-54 years, women with surgical menopause before 35 (2.55, 2.22-2.94) and 35-39 years (1.91, 1.71-2.14) had higher risk of CVD than those with natural menopause (1.59, 1.23-2.05 and 1.51, 1.33-1.72, respectively). Women who experienced surgical menopause at earlier age (<50 years) and took HRT had lower risk of incident CHD than those who were not users of HRT. LIMITATIONS, REASONS FOR CAUTION: Self-reported data on type and age of menopause, no information on indication for the surgery (e.g. endometriosis and fibroids) and the exclusion of fatal CVD events may bias our results. WIDER IMPLICATIONS OF THE FINDINGS: In clinical practice, women who experienced natural menopause or had surgical menopause at an earlier age need close monitoring and engagement for preventive health measures and early diagnosis of CVD. Our findings also suggested that timing of menopause should be considered as an important factor in risk assessment of CVD for women. The findings on CVD lend some support to the position that elective bilateral oophorectomy (surgical menopause) at hysterectomy for benign diseases should be discouraged based on an increased risk of CVD. STUDY FUNDING/COMPETING INTEREST(S): InterLACE project is funded by the Australian National Health and Medical Research Council project grant (APP1027196). GDM is supported by Australian National Health and Medical Research Council Principal Research Fellowship (APP1121844). There are no competing interests.

Vasomotor menopausal symptoms and risk of cardiovascular disease: a pooled analysis of six prospective studies.

BACKGROUND: Menopausal vasomotor symptoms (ie, hot flashes and night sweats) have been associated with unfavorable risk factors and surrogate markers of cardiovascular disease, but their association with clinical cardiovascular disease events is unclear. OBJECTIVE: To examine the associations between different components of vasomotor symptoms, timing of vasomotor symptoms, and risk of cardiovascular disease. STUDY DESIGN: We harmonized and pooled individual-level data from 23,365 women in 6 prospective studies that contributed to the International Collaboration for a Life Course Approach to Women's Reproductive Health and Chronic Disease Events consortium. Women who experienced cardiovascular disease events before baseline were excluded. The associations between frequency (never, rarely, sometimes, and often), severity (never, mild, moderate, and severe), and timing (before or after age of menopause; ie, early or late onset) of vasomotor symptoms and incident cardiovascular disease were analyzed. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals. RESULTS: In the adjusted model, no evidence of association was found between the frequency of hot flashes and incident cardiovascular disease, whereas women who reported night sweats "sometimes" (hazard ratio, 1.22; 95% confidence interval, 1.02-1.45) or "often" (hazard ratio, 1.29; 95% confidence interval, 1.05-1.58) had higher risk for cardiovascular disease. Increased severity of either hot flashes or night sweats was associated with higher risk of cardiovascular disease. The hazards ratios of cardiovascular disease in women with severe hot flashes, night sweats, and any vasomotor symptoms were 1.83 (95% confidence interval, 1.22-2.73), 1.59 (95% confidence interval, 1.07-2.37), and 2.11 (95% confidence interval, 1.62-2.76), respectively. Women who reported severity of both hot flashes and night sweats had a higher risk for cardiovascular disease (hazard ratio, 1.55; 95% confidence interval, 1.24-1.94) than those with hot flashes alone (hazard ratio, 1.33; 95% confidence interval, 0.94-1.88) and night sweats alone (hazard ratio, 1.32; 95% confidence interval, 0.84-2.07). Women with either early-onset (hazard ratio, 1.38; 95% confidence interval, 1.10-1.75) or late-onset (hazard ratio, 1.69; 95% confidence interval, 1.32-2.16) vasomotor symptoms had an increased risk for incident cardiovascular disease compared with women who did not experience vasomotor symptoms. CONCLUSION: Severity rather than frequency of vasomotor symptoms (hot flashes and night sweats) was associated with increased risk of cardiovascular disease. Vasomotor symptoms with onset before or after menopause were also associated with increased risk of cardiovascular disease.

Obesity, smoking, and risk of vasomotor menopausal symptoms: a pooled analysis of eight cohort studies.

BACKGROUND: Frequent and severe vasomotor symptoms during menopause are linked with adverse health outcomes. Understanding modifiable lifestyle factors for the risk of vasomotor menopausal symptoms is important to guide preventive strategies. OBJECTIVE: We investigated the associations between body mass index and smoking, their joint effects with the risk of vasomotor symptoms, and whether the associations differed by menopausal stage. STUDY DESIGN: The International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events pooled data on 21,460 midlife women from 8 studies (median age, 50 years; interquartile range, 49-51 years) for the cross-sectional analysis. Four studies provided data for the prospective analysis (n=11,986). Multinomial logistic regression models with 4 categories of frequency/severity for the outcome of vasomotor symptoms were used to estimate relative risk ratios and 95% confidence intervals that were adjusted for within-study correlation and covariates. RESULTS: At baseline, nearly 60% of the women experienced vasomotor symptoms. One-half of them were overweight (30%) or obese (21%), and 17% were current smokers. Cross-sectional analyses showed that a higher body mass index and smoking more cigarettes with longer duration and earlier initiation were all associated with more frequent or severe vasomotor symptoms. Never smokers who were obese had a 1.5-fold (relative risk ratio, 1.52; 95% confidence interval, 1.35-1.73) higher risk of often/severe vasomotor symptoms, compared with never smokers who were of normal-weight. Smoking strengthened the association because the risk of often/severe vasomotor symptoms was much greater among smokers who were obese (relative risk ratio, 3.02; 95% confidence interval, 2.41-3.78). However, smokers who quit at <40 years of age were at similar levels of risk as never smokers. Prospective analyses showed a similar pattern, but the association attenuated markedly after adjustment for baseline vasomotor symptoms. Furthermore, we found that the association between body mass index and vasomotor symptoms differed by menopausal status. Higher body mass index was associated with increased risk of vasomotor symptoms in pre- and perimenopause but with reduced risk in postmenopause. CONCLUSION: High body mass index (≥25 kg/m2) and cigarette smoking substantially increased women's risk for experiencing frequent or severe vasomotor symptoms in a dose-response manner, and smoking intensified the effect of obesity. However, the effect of body mass index on the risk of vasomotor symptoms was opposite among postmenopausal women. Maintaining a normal weight before the menopausal transition and quitting smoking at <40 years of age may mitigate the excess risk of vasomotor symptoms in midlife.

Premenopausal cardiovascular disease and age at natural menopause: a pooled analysis of over 170,000 women.

Early menopause is associated with an increased risk of subsequent cardiovascular disease (CVD). Few studies have investigated the converse. We examined whether premenopausal CVD events are associated with early age at menopause. We pooled the individual data of 177,131 women from nine studies. We used multinomial logistic regression models to estimate multivariable relative risk ratios (RRR) and 95% confidence intervals (CI) for the associations between age at onset of premenopausal CVD events-including coronary heart disease (CHD) and stroke-and age at natural menopause. Altogether 1561 (0.9%) premenopausal participants reported CVD events (including 1130 CHD and 469 stroke) at a mean age of 41.3 years. Compared with women without any premenopausal CVD events, women who experienced a first CVD event before age 35 years had a twofold risk of menopause before age 45 years (early menopause); adjusted RRR (95% CI) of 1.92 (1.17, 3.14) for any CVD, 1.86 (1.01, 3.43) for CHD and 2.17 (1.43, 3.30) for stroke. Women who experienced a first premenopausal CVD event after age 40 years underwent a natural menopause at the expected age (around 51 years). These associations were robust to adjustment for smoking status, BMI, educational level, race/ethnicity, age at menarche, parity, hypertension and family history of CVD. For premenopausal women, a first CVD event before age 35 years is associated with a doubling of the risk of an early menopause, while a first CVD event occurred after 35 years indicates a normal menopause at around 51 years. Shared genetic and environmental factors (such as smoking), as well as compromised vasculature following CVD events, may contribute to this outcome.

Relationships between intensity, duration, cumulative dose, and timing of smoking with age at menopause: A pooled analysis of individual data from 17 observational studies.

BACKGROUND: Cigarette smoking is associated with earlier menopause, but the impact of being a former smoker and any dose-response relationships on the degree of smoking and age at menopause have been less clear. If the toxic impact of cigarette smoking on ovarian function is irreversible, we hypothesized that even former smokers might experience earlier menopause, and variations in intensity, duration, cumulative dose, and age at start/quit of smoking might have varying impacts on the risk of experiencing earlier menopause. METHODS AND FINDINGS: A total of 207,231 and 27,580 postmenopausal women were included in the cross-sectional and prospective analyses, respectively. They were from 17 studies in 7 countries (Australia, Denmark, France, Japan, Sweden, United Kingdom, United States) that contributed data to the International collaboration for a Life course Approach to reproductive health and Chronic disease Events (InterLACE). Information on smoking status, cigarettes smoked per day (intensity), smoking duration, pack-years (cumulative dose), age started, and years since quitting smoking was collected at baseline. We used multinomial logistic regression models to estimate multivariable relative risk ratios (RRRs) and 95% confidence intervals (CIs) for the associations between each smoking measure and categorised age at menopause (<40 (premature), 40-44 (early), 45-49, 50-51 (reference), and ≥52 years). The association with current and former smokers was analysed separately. Sensitivity analyses and two-step meta-analyses were also conducted to test the results. The Bayesian information criterion (BIC) was used to compare the fit of the models of smoking measures. Overall, 1.9% and 7.3% of women experienced premature and early menopause, respectively. Compared with never smokers, current smokers had around twice the risk of experiencing premature (RRR 2.05; 95% CI 1.73-2.44) (p < 0.001) and early menopause (1.80; 1.66-1.95) (p < 0.001). The corresponding RRRs in former smokers were attenuated to 1.13 (1.04-1.23; p = 0.006) and 1.15 (1.05-1.27; p = 0.005). In both current and former smokers, dose-response relationships were observed, i.e., higher intensity, longer duration, higher cumulative dose, earlier age at start smoking, and shorter time since quitting smoking were significantly associated with higher risk of premature and early menopause, as well as earlier menopause at 45-49 years. Duration of smoking was a strong predictor of age at natural menopause. Among current smokers with duration of 15-20 years, the risk was markedly higher for premature (15.58; 11.29-19.86; p < 0.001) and early (6.55; 5.04-8.52; p < 0.001) menopause. Also, current smokers with 11-15 pack-years had over 4-fold (4.35; 2.78-5.92; p < 0.001) and 3-fold (3.01; 2.15-4.21; p < 0.001) risk of premature and early menopause, respectively. Smokers who had quit smoking for more than 10 years had similar risk as never smokers (1.04; 0.98-1.10; p = 0.176). A limitation of the study is the measurement errors that may have arisen due to recall bias. CONCLUSIONS: The probability of earlier menopause is positively associated with intensity, duration, cumulative dose, and earlier initiation of smoking. Smoking duration is a much stronger predictor of premature and early menopause than others. Our findings highlight the clear benefits for women of early smoking cessation to lower their excess risk of earlier menopause.

The role of sleep difficulties in the vasomotor menopausal symptoms and depressed mood relationships: an international pooled analysis of eight studies in the InterLACE consortium.

BACKGROUND: Many women experience both vasomotor menopausal symptoms (VMS) and depressed mood at midlife, but little is known regarding the prospective bi-directional relationships between VMS and depressed mood and the role of sleep difficulties in both directions. METHODS: A pooled analysis was conducted using data from 21 312 women (median: 50 years, interquartile range 49-51) in eight studies from the InterLACE consortium. The degree of VMS, sleep difficulties, and depressed mood was self-reported and categorised as never, rarely, sometimes, and often (if reporting frequency) or never, mild, moderate, and severe (if reporting severity). Multivariable logistic regression models were used to examine the bi-directional associations adjusted for within-study correlation. RESULTS: At baseline, the prevalence of VMS (40%, range 13-62%) and depressed mood (26%, 8-41%) varied substantially across studies, and a strong dose-dependent association between VMS and likelihood of depressed mood was found. Over 3 years of follow-up, women with often/severe VMS at baseline were more likely to have subsequent depressed mood compared with those without VMS (odds ratios (OR) 1.56, 1.27-1.92). Women with often/severe depressed mood at baseline were also more likely to have subsequent VMS than those without depressed mood (OR 1.89, 1.47-2.44). With further adjustment for the degree of sleep difficulties at baseline, the OR of having a subsequent depressed mood associated with often/severe VMS was attenuated and no longer significant (OR 1.13, 0.90-1.40). Conversely, often/severe depressed mood remained significantly associated with subsequent VMS (OR 1.80, 1.38-2.34). CONCLUSIONS: Difficulty in sleeping largely explained the relationship between VMS and subsequent depressed mood, but it had little impact on the relationship between depressed mood and subsequent VMS.

Female reproductive history and risk of type 2 diabetes: A prospective analysis of 126 721 women.

AIM: To examine the prospective associations between aspects of a woman's reproductive history and incident diabetes. METHODS: We pooled individual data from 126 721 middle-aged women from eight cohort studies contributing to the International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events (InterLACE). Associations between age at menarche, age at first birth, parity and menopausal status with incident diabetes were examined using generalized linear mixed models, with binomial distribution and robust variance. We stratified by body mass index (BMI) when there was evidence of a statistical interaction with BMI. RESULTS: Over a median follow-up of 9 years, 4073 cases of diabetes were reported. Non-linear associations with diabetes were observed for age at menarche, parity and age at first birth. Compared with menarche at age 13 years, menarche at ≤10 years was associated with an 18% increased risk of diabetes (relative risk [RR] 1.18, 95% confidence interval [CI] 1.02-1.37) after adjusting for BMI. After stratifying by BMI, the increased risk was only observed in women with a BMI ≥25 kg/m2 . A U-shaped relationship was observed between parity and risk of diabetes. Compared with pre-/peri-menopausal women, women with a hysterectomy/oophorectomy had an increased risk of diabetes (RR 1.17, 95% CI 1.07-1.29). CONCLUSIONS: Several markers of a woman's reproductive history appear to be modestly associated with future risk of diabetes. Maintaining a normal weight in adult life may ameliorate any increase in risk conferred by early onset of menarche.

Body mass index and age at natural menopause: an international pooled analysis of 11 prospective studies.

Current evidence on the association between body mass index (BMI) and age at menopause remains unclear. We investigated the relationship between BMI and age at menopause using data from 11 prospective studies. A total of 24,196 women who experienced menopause after recruitment was included. Baseline BMI was categorised according to the WHO criteria. Age at menopause, confirmed by natural cessation of menses for ≥ 12 months, was categorised as < 45 years (early menopause), 45-49, 50-51 (reference category), 52-53, 54-55, and ≥ 56 years (late age at menopause). We used multinomial logistic regression models to estimate multivariable relative risk ratios (RRRs) and 95% confidence intervals (CI) for the associations between BMI and age at menopause. The mean (standard deviation) age at menopause was 51.4 (3.3) years, with 2.5% of the women having early and 8.1% late menopause. Compared with those with normal BMI (18.5-24.9 kg/m2), underweight women were at a higher risk of early menopause (RRR 2.15, 95% CI 1.50-3.06), while overweight (1.52, 1.31-1.77) and obese women (1.54, 1.18-2.01) were at increased risk of late menopause. Overweight and obesity were also significantly associated with around 20% increased risk of menopause at ages 52-53 and 54-55 years. We observed no association between underweight and late menopause. The risk of early menopause was higher among obese women albeit not significant (1.23, 0.89-1.71). Underweight women had over twice the risk of experiencing early menopause, while overweight and obese women had over 50% higher risk of experiencing late menopause.

Early menarche, nulliparity and the risk for premature and early natural menopause.

STUDY QUESTION: Are parity and the timing of menarche associated with premature and early natural menopause? SUMMARY ANSWER: Early menarche (≤11 years) is a risk factor for both premature menopause (final menstrual period, FMP <40 years) and early menopause (FMP 40-44 years), a risk that is amplified for nulliparous women. WHAT IS KNOWN ALREADY: Women with either premature or early menopause face an increased risk of chronic conditions in later life and of early death. Findings from some studies suggest that early menarche and nulliparity are associated with early menopause, however overall the evidence is mixed. Much of the evidence for a direct relationship is hampered by a lack of comparability across studies, failure to adjust for confounding factors and inadequate statistical power. STUDY DESIGN, SIZE, DURATION: This pooled study comprises 51 450 postmenopausal women from nine observational studies in the UK, Scandinavia, Australia and Japan that contribute to the International collaboration for a Life course Approach to reproductive health and Chronic disease Events (InterLACE). PARTICIPANTS/MATERIALS, SETTING, METHODS: Age at menarche (categorized as ≤11, 12, 13, 14 and 15 or more years) and parity (categorized as no children, one child and two or more children) were exposures of interest. Age at FMP was confirmed by at least 12 months of cessation of menses where this was not the result of an intervention (such as surgical menopause due to bilateral oophorectomy or hysterectomy) and categorized as premature menopause (FMP before age 40), early menopause (FMP 40-44 years), 45-49 years, 50-51 years, 52-53 years and 54 or more years. We used multivariate multinomial logistic regression models to estimate relative risk ratio (RRR) and 95% CI for associations between menarche, parity and age at FMP adjusting for within-study correlation. MAIN RESULTS AND THE ROLE OF CHANCE: The median age at FMP was 50 years (interquartile range 48-53 years), with 2% of the women experiencing premature menopause and 7.6% early menopause. Women with early menarche (≤11 years, compared with 12-13 years) were at higher risk of premature menopause (RRR 1.80, 95% CI 1.53-2.12) and early menopause (1.31, 1.19-1.44). Nulliparity was associated with increased risk of premature menopause (2.26, 1.84-2.77) and early menopause (1.32, 1.09-1.59). Women having early menarche and nulliparity were at over 5-fold increased risk of premature menopause (5.64, 4.04-7.87) and 2-fold increased risk of early menopause (2.16, 1.48-3.15) compared with women who had menarche at ≥12 years and two or more children. LIMITATIONS, REASONS FOR CAUTION: Most of the studies (except the birth cohorts) relied on retrospectively reported age at menarche, which may have led to some degree of recall bias. WIDER IMPLICATIONS OF THE FINDINGS: Our findings support early monitoring of women with early menarche, especially those who have no children, for preventive health interventions aimed at mitigating the risk of adverse health outcomes associated with early menopause. STUDY FUNDING/COMPETING INTEREST(S): InterLACE project is funded by the Australian National Health and Medical Research Council project grant (APP1027196). G.D.M. is supported by Australian Research Council Future Fellowship (FT120100812). There are no competing interests.

Ethnic Differences in the Association Between Age at Natural Menopause and Risk of Type 2 Diabetes Among Postmenopausal Women: A Pooled Analysis of Individual Data From 13 Cohort Studies.

OBJECTIVE: To investigate associations between age at natural menopause, particularly premature ovarian insufficiency (POI) (natural menopause before age 40 years), and incident type 2 diabetes (T2D) and identify any variations by ethnicity. RESEARCH DESIGN AND METHODS: We pooled individual-level data of 338,059 women from 13 cohort studies without T2D before menopause from six ethnic groups: White (n = 177,674), Chinese (n = 146,008), Japanese (n = 9,061), South/Southeast Asian (n = 2,228), Black (n = 1,838), and mixed/other (n = 1,250). Hazard ratios (HRs) of T2D associated with age at menopause were estimated in the overall sample and by ethnicity, with study as a random effect. For each ethnic group, we further stratified the association by birth year, education level, and BMI. RESULTS: Over 9 years of follow-up, 20,064 (5.9%) women developed T2D. Overall, POI (vs. menopause at age 50-51 years) was associated with an increased risk of T2D (HR 1.31; 95% CI 1.20-1.44), and there was an interaction between age at menopause and ethnicity (P < 0.0001). T2D risk associated with POI was higher in White (1.53; 1.36-1.73), Japanese (4.04; 1.97-8.27), and Chinese women born in 1950 or later (2.79; 2.11-3.70); although less precise, the risk estimates were consistent in women of South/Southeast Asian (1.46; 0.89-2.40), Black (1.72; 0.95-3.12), and mixed/other (2.16; 0.83-5.57) ethnic groups. A similar pattern, but with a smaller increased risk of T2D, was observed with early menopause overall (1.16; 1.10-1.23) and for White, Japanese, and Chinese women born in 1950 or later. CONCLUSIONS: POI and early menopause are risk factors for T2D in postmenopausal women, with considerable variation across ethnic groups, and may need to be considered in risk assessments of T2D among women.

Increased ferritin concentrations correlate with insulin resistance in female type 2 diabetic patients.

AIMS: Iron overload identified by elevated ferritin concentrations has been implicated in risks of altered glucose metabolism and diabetic complications. The relationship between ferritin and insulin resistance in different gender and ethnicities remains uncertain; this study aimed to investigate it using homeostasis model assessment (HOMA-IR), and to explore whether it is gender-specific. METHODS: A total of 524 type 2 diabetic patients were selected cross-sectionally from a cohort participating in a diabetic control study in Taiwan. RESULT: Overall, tertiles of ferritin were significantly and dose-dependently associated with elevated fasting plasma glucose, hemoglobin A1c, high-sensitivity C-reactive protein, HOMA-IR levels as well as Western dietary pattern scores generated by factor analysis (all p trend <0.05). Stratified by gender, a 1-tertile ferritin increase significantly correlated with a 0.241-unit increase in HOMA-IR (beta = 0.241, p = 0.001) in female diabetes, but not in male diabetes (beta = 0.072, p = 0.232), after adjusting for demographic, dietary, clinical and inflammatory factors. CONCLUSION: Iron overload, which produces elevated levels of ferritin, may augment insulin resistance in female but not in male type 2 diabetes. Longitudinal studies are warranted to establish relationships between iron stores and diabetes development in men and women of different ethnicities.

Association between reproductive lifespan and risk of incident type 2 diabetes and hypertension in postmenopausal women: Findings from a 20-year prospective study.

BACKGROUND: This study examined the association between reproductive lifespan and incident type 2 diabetes mellitus (T2DM) and hypertension in mid-age women. Also, the combined effect of reproductive lifespan and body mass index (BMI) on the risks of T2DM and hypertension were explored. METHODS: Reproductive lifespan was defined as the difference between age at menopause and age at menarche, and categorized as <35, 35-37, 38-40, and ≥41 years based on the quartile distribution. A multivariable Cox proportional hazard regression was used, adjusting for socio-demographic, lifestyle, and reproductive factors. RESULTS: Of 6357 postmenopausal women included (mean [SD] age at last follow-up, 66.3[3.3] years), a total of 655 developed incident T2DM (10.3%) and 1741 developed hypertension (30.0%) during 20 years of follow-up. The total sample had a mean (SD) reproductive lifespan of 37.9 (4.5). Compared with the women who had a reproductive lifespan of 38-40 years, those with a short reproductive lifespan (<35 years) had a 30% increased risk of T2DM and twice the risk of hypertension. Under the combined model, women who had a short reproductive lifespan (<35 years) and who had a BMI ≥30 kg/m2 at baseline showed a higher risk of T2DM (HR: 6.30, 95% CI: 4.41-8.99) and hypertension (HR: 6.06, 4.86-7.55) compared with women who had a reproductive lifespan of 38-40 years and a BMI < 25 kg/m2. CONCLUSIONS: A higher risk of both incident T2DM and hypertension at midlife was found among women experiencing a shorter reproductive lifespan, with pronounced risk for women experiencing both a short reproductive lifespan (<35 years) and a higher baseline BMI (≥30 kg/m2). Women with a short reproductive lifespan may benefit from maintaining healthy body weight in midlife.

Epidemiological studies of the association between reproductive lifespan characteristics and risk of Type 2 diabetes and hypertension: A systematic review.

Some reproductive factors are found to be associated with metabolic outcomes in women; however, little is known about reproductive lifespan characteristics and the mutual effect of age at menarche and age at menopause on cardiovascular risk. This systematic review evaluated reproductive lifespan characteristics and describes the mutual effect of age at menarche and age at menopause on the risk of type 2 diabetes (T2DM) and hypertension at midlife. PubMed, EMBASE, and Web of Science were screened for studies published up to September 1, 2020. The individual effect estimates were reviewed and synthesized without meta-analysis due to methodological and clinical or conceptual diversity in reported studies. Of the 3033 identified studies, 20 were included in the final synthesis: 6 reported reproductive life span; 12 reported age at menarche, and 7 reported age at menopause. Synthesis of two cohorts, with a median follow-up of 9-11 years, showed that a shorter reproductive lifespan was positively associated with T2DM, yielding 6-15% higher risk of T2DM for a one-year decrease in reproductive lifespan. A few studies also demonstrated that women who experienced early menarche (four of six studies) and early menopause (two of five studies) were positively associated with risk of T2DM. The association between reproductive lifespan and hypertension was unclear due to the limited availability of studies. Our findings suggest that a shorter reproductive lifespan is associated with T2DM risk in postmenopausal women, especially those with early menarche and early menopause. Large cohort studies are needed to assess the association between reproductive lifespan and incident hypertension in midlife.

Infertility, recurrent pregnancy loss, and risk of stroke: pooled analysis of individual patient data of 618 851 women.

OBJECTIVE: To examine the associations of infertility, recurrent miscarriage, and stillbirth with the risk of first non-fatal and fatal stroke, further stratified by stroke subtypes. DESIGN: Individual participant pooled analysis of eight prospective cohort studies. SETTING: Cohort studies across seven countries (Australia, China, Japan, Netherlands, Sweden, the United Kingdom, and the United States) participating in the InterLACE (International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events) consortium, which was established in June 2012. PARTICIPANTS: 618 851 women aged 32.0-73.0 years at baseline with data on infertility, miscarriage, or stillbirth, at least one outcome event (non-fatal or fatal stroke), and information on covariates were included; 93 119 women were excluded. Of the participants, 275 863 had data on non-fatal and fatal stroke, 54 716 only had data on non-fatal stroke, and 288 272 only had data on fatal stroke. MAIN OUTCOME AND MEASURES: Non-fatal strokes were identified through self-reported questionnaires, linked hospital data, or national patient registers. Fatal strokes were identified through death registry data. RESULTS: The median follow-up for non-fatal stroke and fatal stroke was 13.0 years (interquartile range 12.0-14.0) and 9.4 years (7.6-13.0), respectively. A first non-fatal stroke was experienced by 9265 (2.8%) women and 4003 (0.7%) experienced a fatal stroke. Hazard ratios for non-fatal or fatal stroke were stratified by hypertension and adjusted for race or ethnicity, body mass index, smoking status, education level, and study. Infertility was associated with an increased risk of non-fatal stroke (hazard ratio 1.14, 95% confidence interval 1.08 to 1.20). Recurrent miscarriage (at least three) was associated with higher risk of non-fatal and fatal stroke (1.35, 1.27 to 1.44, and 1.82, 1.58 to 2.10, respectively). Women with stillbirth were at 31% higher risk of non-fatal stroke (1.31, 1.10 to 1.57) and women with recurrent stillbirth were at 26% higher risk of fatal stroke (1.26, 1.15 to 1.39). The increased risk of stroke (non-fatal or fatal) associated with infertility or recurrent stillbirths was mainly driven by a single stroke subtype (non-fatal ischaemic stroke and fatal haemorrhagic stroke), while the increased risk of stroke (non-fatal or fatal) associated with recurrent miscarriages was driven by both subtypes. CONCLUSION: A history of recurrent miscarriages and death or loss of a baby before or during birth could be considered a female specific risk factor for stroke, with differences in risk according to stroke subtypes. These findings could contribute to improved monitoring and stroke prevention for women with such a history.