Secular trend in the menopausal age in Finland 1997-2007 and correlation with socioeconomic, reproductive and lifestyle factors

Secular trends in premature and early menopause in low-income and middle-income countries

BACKGROUND

While secular trends in high-income countries show an increase in the mean age at menopause, it is unclear if there is a similar pattern in low-income and middle-income countries (LMICs), where women's exposure to biological, environmental and lifestyle determinants of menopause may differ. Premature (before age 40 years) and early (ages 40-44 years) menopause could have negative repercussions on later life health outcomes which in ageing societies could mean further stress on low-resource health systems. An evaluation of such trends in LMICs has been hampered by the suitability, quality and comparability of data from these countries.

METHODS

Using 302 standardised household surveys from 1986 to 2019, we estimate trends and CIs using bootstrapping in the prevalence of premature and early menopause in 76 LMICs. We also developed a summary measure of age at menopause for women who experience menopause before the age of 50 years based on demographic estimation methods that can be used to measure menopausal status in surveys with truncated data.

RESULTS

Trends indicate an increasing prevalence of early and premature menopause in LMICs, in particular in sub-Saharan Africa and South/Southeast Asia. These regions also see a suggested decline of the mean age at menopause with greater variation across continents.

CONCLUSIONS

This study enables the analysis of menopause timing by exploiting data generally used for the study of fertility by methodologically allowing the use of truncated data. Findings show a clear increase in prevalence of premature and early menopause in the regions with the highest fertility with possible consequences for later life health. They also show a different trend compared with high-income regions, confirming a lack of generalisability and the importance of accounting for nutritional and health transitions at the local level. This study calls for further data and research on menopause on a global scale.

Is Alcohol Consumption Associated With Risk of Early Menopause?

Earlier age at menopause is associated with increased long-term health risks. Moderate alcohol intake has been suggested to delay menopause onset, but it is unknown whether alcohol subtypes are associated with early menopause onset at age 45 years. Therefore, we aimed to evaluate risk of early natural menopause among 107,817 members of the Nurses' Health Study II who were followed from 1989 to 2011. Alcohol consumption overall and by subtypes, including beer, red wine, white wine, and liquor, was assessed throughout follow-up. We estimated hazard ratios in multivariable models that were adjusted for age, body mass index, parity, smoking, and other potential confounders. Women who reported moderate current alcohol consumption had lower risks of early menopause than did nondrinkers. Those who reported consuming 10.0-14.9 g/day had a lower risk of early menopause than did nondrinkers (hazard ratio = 0.81, 95% confidence interval: 0.68, 0.97). Among specific beverages, evidence of lower early menopause risk was confined to consumption of white wine and potentially red wine and liquor, but not to beer. Data from this large prospective study suggest a weak association of moderate alcohol intake with lower risk of early menopause, which was most pronounced for consumption of white and red wine and liquor. High consumption was not related to lower risk of early menopause.

Parity, menopausal hormone therapy, and risk of ovarian granulosa cell tumor - A population-based case-control study

OBJECTIVE

Adult-type ovarian granulosa cell tumors (AGCTs) are hormonally active neoplasms with limited epidemiological data available. We evaluated the effect of parity and postmenopausal hormone therapy (HT) use on the risk of AGCT in a population-based case-control setting.

METHODS

We identified all women diagnosed with AGCT during 1994-2015 (n = 505) from the Finnish Cancer Registry. For each case, five controls matched for age were selected from the National Population Registry, which also provided data on parity and ages at deliveries. Information on postmenopausal HT by different regimens (estradiol-only, sequential estrogen-progestin and continuous estrogen-progestin) was obtained from nationwide Prescription Register. The association between parity, ages at deliveries, HT use, and AGCT incidence was evaluated by odds ratios (ORs) using a conditional logistic regression model and stratified by age at index date (<55 years or ≥ 55 years).

RESULTS

Parity and age at first or last delivery had no significant effect on AGCT risk. Systemic postmenopausal HT had been used by 20.4% of women who were later diagnosed with AGCT. The risk for subsequent AGCT was significantly decreased among users of estradiol-only therapy for at least five years (OR 0.28; 95% confidence interval 0.08-0.94) and continuous estradiol-progestin therapy for 6 months to 5 years (0.23; 0.08-0.71).

CONCLUSIONS

Unlike in epithelial ovarian cancer, AGCT development is not clearly associated with parity, and users of postmenopausal HT do not seem to carry an excess risk for AGCT formation.

Can time to menopause be predicted?

Menopause represents the definite end of a woman's reproductive life and the onset of a persistent hypoestrogenic state. This postmenopausal period will for most women last several decades. Although mean menopausal age seems to have increased somewhat during the last century, there is a significant individual variation in age at natural menopause. With efficient contraception, women of reproductive age can now, to some extent, choose when they want to have children. As a consequence of this and other sociodemographic changes, age at first birth has increased significantly over the last 50 years. It is well documented that long before a woman enters the menopausal transition and subsequent menopause, fertility declines and finally ceases. Being able to predict when a woman will enter menopause would therefore, from a reproductive perspective, be of major interest. Several sociodemographic, morphometric, and endocrine factors are associated with age at menopause or time to menopause. Unfortunately the sensitivity and specificity of these in predicting time to or age at menopause are low. Therefore, with the exception of anti-Müllerian hormone measurements, either alone or in combination with chronological age close to menopause, there are as of now no reliable ways of predicting when a woman will enter menopause.

Predicted reproductive longevity and women's facial attractiveness

Physical attractiveness has been shown to reflect women's current fecundity level, allowing a man to choose a potentially more fertile partner in mate choice context. However, women vary not only in terms of fecundity level at reproductive age but also in reproductive longevity, both influencing a couple's long-term reproductive success. Thus, men should choose their potential partner not only based on cues of current fecundity but also on cues of reproductive longevity, and both may be reflected in women's appearance. In this study, we investigated if a woman's facial attractiveness at reproductive age reflects anti-Müllerian hormone (AMH) level, a hormone predictor of age at menopause, similarly as it reflects current fecundity level, estimated with estradiol level (E2). Face photographs of 183 healthy women (Mage = 28.49, SDage = 2.38), recruited between 2nd - 4th day of the menstrual cycle, were assessed by men in terms of attractiveness. Women's health status was evaluated based on C-reactive protein level and biochemical blood test. Serum AMH and E2 were measured. The results showed that facial attractiveness was negatively correlated with AMH level, a hormone indicator of expected age at menopause, and positively with E2, indicator of current fecundity level, also when controlled for potential covariates (testosterone, BMI, age). This might result from biological trade-off between high fecundity and the length of reproductive lifespan in women and greater adaptive importance of high fecundity at reproductive age compared to the length of reproductive lifespan.

Trends of Premature and Early Menopause: a Comparative Study of the US National Health and Nutrition Examination Survey and the Korea National Health and Nutrition Examination Survey

BACKGROUND

While evidence shows a tendency toward delays in menopause worldwide, whether prevalence of premature (< 40 years) or early menopause (40-44 years) is also reduced in different ethnic groups is uncertain. The aim of this study was to explore birth cohort effect in the prevalence of premature and early menopause in United States (US) and Korea.

METHODS

This is a retrospective study using the National Health and Nutrition Examination Survey (NHANES, 1999-2014) and the Korea NHANES (KNHANES, 2007-2012). We analyzed prevalence of premature and early menopause in three ethnic groups of US and Korea. We restricted our analysis to women aged ≥ 45 years at the time of the survey born between 1920 and 1969. The data of both eligible 9,209 US women and 9,828 Korean was included in final analysis. We calculated odds ratios (OR) for each outcome adjusting for biological and socioeconomic factors, respectively.

RESULTS

Prevalence of premature menopause was 1.7% in US, 2.8% in Korean women. Early menopause occurred in 3.4% and 7.2% of US and Korean, respectively. In US women, prevalence of premature and early menopause did not change and did not differ across three ethnicities. Korean women showed highest and consistently decreasing prevalence (P < 0.001). When we adjusted for covariates, birth lower risk for premature menopause was evident in US Non-Hispanic black born in 1950s and in Korean born between 1940s and 1960s compared to those born in 1920s. In the analysis of early menopause, excluding premature menopause patients, lower risk of more recent generation (born in 1940s and later) was evident in Korean women.

CONCLUSION

The trend and birth cohort effect in occurrence of premature and early menopause among the US and Korea women are different. Prevalences of premature and early menopause decrease only in Korean.

Is it possible to investigate menopausal age? A comparative cross-sectional study of five cohorts between 1968 and 2017 from the Population Study of Women in Gothenburg, Sweden

OBJECTIVE

The aim of this study was to examine if the previously found trend of increasing menopausal age is continuing, taking into consideration hormonal use and surgical menopause in both 38- and 50-year-old women of today.

METHODS

Cohort comparisons of five generations of population-based samples of 38- and 50-year-old women from the Prospective Population Study of Women in Gothenburg with start in 1968/1969, and with follow-ups in 1980/1981, 1992/1993, 2004/2005, and 2016/2017. Across the time periods newly recruited women as well as earlier participants were included. Use of hormonal contraceptives, estrogen plus progestogen therapy (EPT), and time for menopause was registered. Changes between different generations of 38- and 50-year-old women from 1968/1969 until today were studied. The overall sample size across the time periods was 1,873 individuals.

RESULTS

The prevalence of oral contraceptives in 38-year-old women was about 10% in 1968/1969, increasing from 16% in 2004/2005 to almost 22% in 2016/2017. From 2004/2005 the use of hormonal intrauterine contraceptive method (the Levonorgestrel-releasing intrauterine system [LNG-IUS]) increased from about 11% to 14% in 2016/2017. The same pattern was found in 50-year-old women using LNG-IUS, increasing from 6% to 15.5% between 2004/2005 and 2016/2017. The total hormonal use, including LNG-IUS, oral contraceptives, and EPT, was 28% in 50-year-old women in 2016/2017. The total proportion of hormone use in 50-year-old women increased over the years and together with surgical menopause it reached over 37% in the 2016/2017 survey.

CONCLUSIONS

This study has shown an increase in the hormonal use, in both 38- and 50-year-old women, making it difficult to determine when the actual menopause occurs. Thus, the previously found increasing secular trend in menopausal age will be more complicated to assess in female generations of today and tomorrow.

Change in mammographic density across birth cohorts of Dutch breast cancer screening participants

High mammographic density is a well‐known risk factor for breast cancer. This study aimed to search for a possible birth cohort effect on mammographic density, which might contribute to explain the increasing breast cancer incidence. We separately analyzed left and right breast density of Dutch women from a 13‐year period (2003–2016) in the breast cancer screening programme. First, we analyzed age‐specific changes in average percent dense volume (PDV) across birth cohorts. A linear regression analysis (PDV vs. year of birth) indicated a small but statistically significant increase in women of: 1) age 50 and born from 1952 to 1966 (left, slope = 0.04, p = 0.003; right, slope = 0.09, p < 0.0001); 2) age 55 and born from 1948 to 1961 (right, slope = 0.04, p = 0.01); and 3) age 70 and born from 1933 to 1946 (right, slope = 0.05, p = 0.002). A decrease of total breast volume seemed to explain the increase in PDV. Second, we compared proportion of women with dense breast in women born in 1946–1953 and 1959–1966, and observed a statistical significant increase of proportion of highly dense breast in later born women, in the 51 to 55 age‐groups for the left breast (around a 20% increase in each age‐group), and in the 50 to 56 age‐groups for the right breast (increase ranging from 27% to 48%). The study indicated a slight increase in mammography density across birth cohorts, most pronounced for women in their early 50s, and more marked for the right than for the left breast.

What's new?

Women with dense breast tissue are at increased risk of breast cancer. Here, changes in mammographic density were investigated across birth cohorts in women enrolled in a breast cancer screening program in the Netherlands. The findings reveal an increase in the average fraction of dense tissue in the breast across cohorts. In particular, greater breast density was observed in a higher proportion of women in later‐born than earlier‐born birth cohorts. The increase was most significant among women in their early 50s and may be linked to a reported shift toward older age at menopause among women in Europe.

Reproductive Assessment: Findings from 20 Years of the Tehran Lipid and Glucose Study

CONTEXT

Reproductive domains of the Tehran lipid and glucose study (TLGS) are unique in that they provide reliable information on reproduction of an urban population of West Asia. The aim of this review is to present the most important reproductive findings of TLGS.

EVIDENCE ACQUISITION

This review is summarizing all articles published in the context of reproductive aspects of TLGS results over the 20-year follow-up. A comprehensive databases search was conducted in PubMed (including Medline), Web of Science and Scopus for retrieving articles on the reproductive histories in context of the TLGS.

RESULTS

The mean (SD) age at menarche and menopause was 13 (1.2) and 49.6 (4.5) years respectively. While pills were the most commonly used modern methods at the initiation of TLGS, the prevalence of condoms rose sharply and significantly over the follow up duration. Among women with history of gestational diabetes, the risk of diabetes and dyslipidemia progression were 2.44 and 1.2 fold higher than others. Prevalences of PCOS and idiopathic hirsutism among reproductive age participants of TLGS were 8.5% (95% CI: 6.8% - 10.2%) and 13.0% (95% CI: 10.9% - 15.1%), respectively. Trend of cardio-metabolic risk factors among women with PCOS showed that there were no statistically significant differences between mean changes of each cardio metabolic variables between PCOS and healthy women; PCOS status also significantly associated with increased hazard of diabetes and prediabetes among women aged younger than 40 years (HR: 4.9; 95% CI: 2.5 - 9.3, P value < 0.001)) and (HR: 1.7; 95% CI: 1.1 - 2.6), P value < 0.005), respectively.

CONCLUSIONS

The population based nature of TLGS provides a unique opportunity for valid assessment of reproductive issues, the results of which could provide new information for modification of existing guidelines.

On Exploring Hidden Structures Behind Cervical Cancer Incidence

Finding new etiological components is of great interest in disease epidemiology. We consider time series version of invariant coordinate selection (tICS) as an exploratory tool in the search of hidden structures in the analysis of population-based registry data. Increasing cancer burden inspired us to consider a case study of age-stratified cervical cancer incidence in Finland between the years 1953 and 2014. The latent components, which we uncover using tICS, show that the etiology of cervical cancer is age dependent. This is in line with recent findings related to the epidemiology of cervical cancer. Furthermore, we are able to explain most of the variation of cervical cancer incidence in different age groups by using only two latent tICS components. The second tICS component, in particular, is interesting since it separates the age groups into three distinct clusters. The factor that separates the three clusters is the median age of menopause occurrence.

Cosmetics use and age at menopause: is there a connection?

Cosmetics contain a vast number of chemicals, most of which are not under the regulatory purview of the Food and Drug Administration. Only a few of these chemicals have been evaluated for potential deleterious health impact: parabens, phthalates, polycyclic aromatic hydrocarbons, and siloxanes. A review of the ingredients in the best-selling and top-rated products of the top beauty brands in the world, as well as a review of highlighted chemicals by nonprofit environmental organizations, reveals 11 chemicals and chemical families of concern: butylated hydroxyanisole/butylated hydroxytoluene, coal tar dyes, diethanolamine, formaldehyde-releasing preservatives, parabens, phthalates, 1,4-dioxane, polycyclic aromatic hydrocarbons, siloxanes, talc/asbestos, and triclosan. Age at menopause can be affected by a variety of mechanisms, including endocrine disruption, failure of DNA repair, oxidative stress, shortened telomere length, and ovarian toxicity. There is a lack of available studies to make a conclusion regarding cosmetics use and age at menopause. What little data there are suggest that future studies are warranted. Women with chronic and consistent use of cosmetics across their lifespan may be a population of concern. More research is required to better elucidate the relationship and time windows of vulnerability and the effects of mixtures and combinations of products on ovarian health.

Association of alcohol consumption with the onset of natural menopause: a systematic review and meta-analysis

BACKGROUND

Early onset of menopause is associated with long-term health risks, including cardiovascular disease and premature death. Although alcohol intake has been suggested to affect the age at which natural menopause occurs, results from observational studies are not consistent.

OBJECTIVE AND RATIONALE

In the view of the differing risks to the health of early menopause and the increasing trends in alcohol consumption in women, in this systematic review, we aimed to quantify the association between all levels of alcohol consumption and menopause onset.

SEARCH METHODS

Six electronic databases (Medline, Embase, Cochrane, PubMed, Google Scholar and Web of Science) were systematically searched until 4 November 2015 to identify relevant studies assessing the association between alcohol consumption and onset of menopause. Two independent reviewers screened the titles and abstracts of all initially identified studies according to the selection criteria. Studies were sought if they (i) were observational cross-sectional, prospective and interventional studies, (ii) had reported on natural onset of menopause, (iii) had reported on alcohol consumption, (iv) had assessed the association between alcohol consumption and menopause onset, (v) were conducted in humans and (vi) were not conducted in patients with cancer. Data were extracted by two independent reviewers using a predesigned data-collection form. The primary exposure variable was the presence of active alcohol drinking at baseline compared with a reference group of non-drinkers. Pooled relative risks (RRs) were calculated.

OUTCOMES

Of the 1193 references (all in English language) reviewed for eligibility, 22 articles based on 20 unique studies were included in the final analysis. A total of 41 339 and 63 868 non-overlapping women were included in the meta-analysis of cross-sectional and observational cohort studies, respectively. In cross-sectional studies, the pooled RR for earlier onset of menopause was 0.86 (95% confidence interval (CI): 0.78-0.96) between drinkers versus non-drinkers. Analysis of the levels of alcohol consumed showed that low and moderate alcohol consumption (more than one drink per week (RR = 0.60; 95% CI: 0.49-0.75) and three or fewer drinks per week (RR = 0.75; 95% CI: 0.60-0.94)) were associated with later menopause onset, compared to non-drinkers. In prospective studies, RR for earlier menopause onset was 0.95 (95% CI: 0.91-0.98) when comparing women who reported drinking alcohol versus women who did not. Analysis of the dose of alcohol consumed showed that low-to-moderate alcohol intake (0-8 g/day (RR = 0.95; 95% CI: 0.93-0.98), and 16 g/day (RR = 0.89, 95%CI: 0.86-0.92)) was associated with later menopause onset, compared to non-drinking.

WIDER IMPLICATIONS

The findings of this review indicate that alcohol consumption, particularly low and moderate alcohol intake, might be associated with later onset of menopause although the magnitude of the association is low. Further studies are needed to corroborate these findings, clarify the level of alcohol intake at which menopause is delayed and identify the potential mechanisms behind this association.

Greater Calcium Intake is Associated with Better Bone Health Measured by Quantitative Ultrasound of the Phalanges in Pediatric Patients Treated with Anticonvulsant Drugs

We aimed to investigate and compare the effects of chronic antiepileptic therapy on bone health in pediatric patients using quantitative ultrasound of the phalanges (QUS) and controlling for potential confounding factors, particularly nutrient intake. The amplitude-dependent speed of sound (Ad-SoS) was measured in 33 epileptic children and 32 healthy children aged 6.5 ± 3.1 and 6.3 ± 1.1 (mean ± SD) years, respectively. There were no significant differences in the demographics such as age, weight and height between epileptic children and the control group children. None of the children in the epileptic or the treatment group were found to have a vitamin D deficiency. There were no significant differences in laboratory tests between groups. Lower QUS figures were found in the epileptic children (p = 0.001). After further adjustment for potential confounders such age, height, weight, calcium intake, vitamin D intake, physical activity and sex, the differences remained significant (p < 0.001). After further classification of the participants based on the tertile of calcium intake, no significant differences were found between patients and healthy controls in the greatest tertile of calcium intake (p = 0.217). We conclude that anticonvulsant therapy using valproate may lead to low bone mass in children and that an adequate intake of calcium might counteract such deleterious effects.

Age at natural menopause in three central and eastern European urban populations: the HAPIEE study

OBJECTIVES

To investigate the age at menopause in three urban populations in Central and Eastern Europe and to assess whether the (suspected) differences can be explained by a range of socioeconomic, reproductive and behavioural factors.

METHODS

The Health, Alcohol and Psychosocial factors in Eastern Europe (HAPIEE) Study examined random samples of populations aged 45-69 years in Novosibirsk (Russia), Krakow (Poland) and six Czech towns. Participants completed a questionnaire and attended an examination in clinic. A total of 12,676 of women were included in these analyses.

RESULTS

The median age at menopause was 50 years in Novosibirsk, 51 years in Czech towns and 52 years in Krakow; the Cox regression hazard ratios of menopause, compared with Krakow, were 1.47 (95% CI 1.40-1.55) for Novosibirsk and 1.10 (1.04-1.16) for Czech women. In multivariate analyses, higher education, using vitamin and mineral supplements and ever use of oral contraceptives were associated with later menopause, while smoking, abstaining from alcohol and low physical activity were associated with earlier menopause. These factors, however, did not explain the differences between populations; the multivariate hazard ratios of menopause, compared with Krakow, were 1.48 (1.40-1.57) for Novosibirsk and 1.11 (1.05-1.17) for Czech women.

CONCLUSIONS

In this large population based study, differences in age at menopause between Central and Eastern Europe populations were substantial and unexplained by a range of risk factors. Associations of age at menopause with risk factors were largely consistent with studies in other populations.

Discrimination of fractures by low-frequency axial transmission ultrasound in postmenopausal females

SUMMARY

In this cross-sectional study, 95 postmenopausal women, with and without fracture history, were measured by low-frequency axial transmission ultrasound. The measured ultrasound velocity discriminated the fractured subjects from the nonfractured ones equally or better than peripheral quantitative computed tomography (pQCT) and dual energy x-ray absorptiometry (DXA). These results suggest that low-frequency ultrasound is suitable for bone fragility assessment.

INTRODUCTION

Quantitative low-frequency axial transmission ultrasound is a promising modality for assessing mineral density and geometrical properties of long bones such as radius and tibia. The aim of the current study was to evaluate the ability of low-frequency axial transmission ultrasound to discriminate fractures retrospectively in postmenopausal women.

METHODS

A cross-sectional study involved 95 female subjects aged 45-88 years, whose fracture information was gathered retrospectively. The fracture group was defined as subjects with one or more low-/moderate-energy fractures. The radius and tibial shaft were measured with a custom-made ultrasonometer to assess the velocity of the low-frequency first-arriving signal (V (LF)). Site-matched pQCT was used to measure volumetric cortical and subcortical bone mineral density (sBMD), and cortical thickness (CTh). Areal BMD (aBMD) was measured using DXA for the whole body (WB), lumbar spine, and hip.

RESULTS

The majority (19/32; 59 %) of the fractures were in the upper limb. V (LF) in the radius, but not in the tibia, discriminated fractures with an age- and BMI-adjusted odds ratio (OR) of 2.06 (95 % CI 1.21-3.50, p < 0.01). In the radius, CTh and cortical BMD (CBMD) significantly discriminated fractures, as did the total, cortical, and sBMD in the tibia (adjusted OR 1.35-2.15, p < 0.05). Sensitivity and specificity were similar among all the measurements (area under the receiver operating characteristic curve 0.74-0.81, p < 0.001).

CONCLUSIONS

Low-frequency axial transmission ultrasound in the radius was able to discriminate fractured subjects from the nonfractured ones. This suggests that low-frequency axial transmission ultrasound has the potential to assess bone fragility in postmenopausal women.

Bone ultrasound and physical activity in postmenopausal Spanish women

We studied the effects of moderate physical activity on bone mass in healthy postmenopausal women as assessed by quantitative bone ultrasound. We enrolled a total of 326 postmenopausal women (60.95 ± 8.51 years old and 13.02 ± 9.52 years since menopause) and categorized them by weekly physical activity in their leisure time (sedentary, moderate, and active). We administered a questionnaire on general health and diet and measured bone density by ultrasound on phalanges II-V in the nondominant hand. We found no significant difference in the amplitude-dependent speed of sound (Ad-SoS; p > .05) between sedentary and active women. We concluded that the changes induced by moderate physical activity on bone mass are minimal in healthy postmenopausal women.

A nationwide cohort study on the incidence of meningioma in women using postmenopausal hormone therapy in Finland

The authors conducted a nationwide cohort study to evaluate the association between postmenopausal hormone therapy and meningioma incidence in Finland. All women who had used hormone therapy at least for 6 months at the age of 50 years or older during 1994-2009 were included. Women who had used postmenopausal hormone therapy were identified from the medical reimbursement register of the Social Insurance Institution (131,480 estradiol users and 131,248 estradiol-progestin users), and meningioma cases were identified from the Finnish Cancer Registry. During the average 9 years of follow-up, 289 estradiol users and 196 estradiol-progestin users were diagnosed with meningioma. Ever use of estradiol-only therapy was associated with an increased risk of meningioma (standardized incidence ratio = 1.29, 95% confidence interval: 1.15, 1.44). Among women who had been using estradiol-only therapy for at least 3 years, the incidence of meningioma was 1.40-fold higher (95% confidence interval: 1.18, 1.64; P < 0.001) than in the background population. In contrast, this risk was not increased in users of combination therapy (standardized incidence ratio = 0.93, 95% confidence interval: 0.80, 1.06). There was no difference in risk between continuous and sequential use of hormone therapy. Estradiol-only therapy was accompanied with a slightly increased risk of meningioma.

Menopause, A Biocultural Perspective

Each menopausal body is the product of decades of physiological responses to an environment composed of cultural and biological factors. Anthropologists have documented population differences in reproductive endocrinology and developmental trajectories, and ethnic differences in hormones and symptoms at menopause demonstrate that this stage of life history is not exempt from this pattern. Antagonistic pleiotropy, in the form of constraints on the reproductive system, may explain the phenomenon of menopause in humans, optimizing the hormonal environment for reproduction earlier in the life course. Some menopausal symptoms may be side effects of modernizing lifestyle changes, representing discordance between our current lifestyles and genetic heritage. Further exploration of women's experience of menopause, as opposed to researcher-imposed definitions; macro- and microenvironmental factors, including diet and intestinal ecology; and folk etiologies involving the autonomic nervous system may lead to a deeper understanding of the complex biocultural mechanisms of menopause.