Reproductive factors and age at natural menopause: A systematic review and meta-analysis

Factors affecting age at menopause and their relationship with ovarian reserve: a comprehensive review

OBJECTIVE

The aim of this article was to discuss all the factors affecting the age at menopause and their correlation with ovarian reserve.

MATERIALS AND METHODS

A narrative review of original articles was performed using PubMed until December 2023. The following keywords were used to generate the list of citations: 'menopause', 'ovarian reserve' 'oocytes quality and quantity', 'ovarian ageing'.

RESULTS

Menopause is the final step in the process of ovarian ageing and is influenced by the oocyte pool at birth. Conditions that accelerate follicle depletion during the reproductive lifespan lead to premature ovarian insufficiency (POI) and premature ovarian failure (POF), while a higher ovarian reserve is associated with a delayed time to menopause. Reproductive history, sociodemographic, lifestyle and iatrogenic factors may impact ovarian reserve and the age at menopause.

CONCLUSIONS

Some factors affecting the age at menopause are modifiable and the risks of early menopause may be preventable. We hypothesise that by addressing these modifiable factors we may also preserve ovarian reserve. However, further interventional studies are needed to evaluate the effects of the described strategies on ovarian reserve.

DNA methylation as a window into female reproductive aging

People with ovaries experience reproductive aging as their reproductive function and system declines. This has significant implications for both fertility and long-term health, with people experiencing an increased risk of cardiometabolic disorders after menopause. Reproductive aging can be assessed through markers of ovarian reserve, response to fertility treatment or molecular biomarkers, including DNA methylation. Changes in DNA methylation with age associate with poorer reproductive outcomes, and epigenome-wide studies can provide insight into genes and pathways involved. DNA methylation-based epigenetic clocks can quantify biological age in reproductive tissues and systemically. This review provides an overview of hallmarks and theories of aging in the context of the reproductive system, and then focuses on studies of DNA methylation in reproductive tissues.

Age at Natural Menopause and Influencing Factors in Women Attending the Gynecological Outpatient Clinic at a Tertiary Care Hospital

Background

Menopause is the irreversible cessation of menstruation that results from the lack of ovarian follicular function and is diagnosed after 12 consecutive months of amenorrhea without reasonable cause. This study aims to determine the average age at natural menopause and identify its associated factors among Somali women.

Methods

This is a cross-sectional study conducted at the Mogadishu Somalia Türkiye Recep Tayyip Erdogan research and training hospital's Obstetrics and Gynecology outpatient clinic between June 1 and July 1, 2023. Data was collected from subjects during the data collection period using face-to-face interviews with structured questionnaires consisting of sociodemographic, lifestyle, dietary, and reproductive characteristics. A multivariate logistic regression analysis was conducted to find the association between menopause age and target variables.

Results

Out of the 188 participants recruited for the study, the median age of menopause was 45.00 (95% CI = 44.50-45.62), and 48.9% had either premature or early menopause. The majority (53.7%) of the participants had a minimum of eight children. In Spearman's rank correlation analysis, we found a significantly positive correlation between menopausal age and age at first (p<0.01), last childbirth (p<0.01), number of parities (p<0.05), and age at marriage (p<0.05). In multivariate logistic regression, we found that the odds of developing premature or early menopause among unemployed women were 59% lower than those of employed women (AOR = 0.41, 95% CI = 0.18-0.93).

Conclusion

In this study, we established that the age of natural menopause was lower than the findings reported by previous authors. We also found that employment status, education, history of contraceptive use, BMI, age at first and last childbirth, and parity were associated with age at natural menopause, suggesting that social, lifestyle, and reproductive factors may have an impact on menopausal age.

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.

Association of infertility with type and timing of menopause: a prospective cohort study

STUDY QUESTION

What is the association between past infertility and the type and timing of menopause in midlife women?

SUMMARY ANSWER

Women with a history of infertility were more likely to experience surgical menopause overall and had elevated risk of earlier surgical menopause until age 43 years but experienced no differences in the timing of natural menopause.

WHAT IS KNOWN ALREADY

Infertility is experienced by 12-25% of women and is thought to reveal a propensity for poor health outcomes, such as chronic illness, later in life. However, little is known about whether infertility is linked with characteristics of the menopausal transition as women age, despite possible shared underlying pathways involving ovarian function and gynecologic disease.

STUDY DESIGN, SIZE, DURATION

Secondary analysis of a prospective cohort study of 13 243 midlife females recruited in Phase 1 of the Alberta's Tomorrow Project (Alberta, Canada) and followed approximately every 4 years (2000-2022).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data were collected through standardized self-report questionnaires. History of infertility, defined as ever trying to become pregnant for more than 1 year without conceiving, was measured at baseline. Menopause characteristics were measured at each study follow-up. Menopause type was defined as premenopause, natural menopause, surgical menopause (bilateral oophorectomy), or indeterminate menopause (premenopausal hysterectomy with ovarian conservation). Timing of natural menopause was defined as the age at 1 full year after the final menstrual period, and timing of surgical and indeterminate menopause was defined as the age at the time of surgery. We used flexible parametric survival analysis for the outcome of menopause timing with age as the underlying time scale and multinomial logistic regression for the outcome of menopause type. Multivariable models controlled for race/ethnicity, education, parity, previous pregnancy loss, and smoking. Sensitivity analyses additionally accounted for birth history, menopausal hormone therapy, body mass index, chronic medical conditions, and age at baseline.

MAIN RESULTS AND THE ROLE OF CHANCE

Overall, 18.2% of women reported a history of infertility. Past infertility was associated with earlier timing of surgical menopause exclusively before age 43 years (age 35: adjusted hazard ratio 3.13, 95% CI 1.95-5.02; age 40: adjusted hazard ratio 1.83, 95% CI 1.40-2.40; age 45: adjusted hazard ratio 1.13, 95% CI 0.87-1.46) as well as greater odds of experiencing surgical menopause compared to natural menopause (adjusted odds ratio 1.40, 95% CI 1.18-1.66). Infertility was not associated with the timing of natural or indeterminate menopause.

LIMITATIONS, REASONS FOR CAUTION

Information on the underlying cause of infertility and related interventions was not collected, which precluded us from disentangling whether associations differed by infertility cause and treatment. Residual confounding is possible given that some covariates were measured at baseline and may not have temporally preceded infertility.

WIDER IMPLICATIONS OF THE FINDINGS

Women with a history of infertility were more likely to experience early surgical menopause and may therefore benefit from preemptive screening and treatment for gynecologic diseases to reduce bilateral oophorectomy, where clinically appropriate, and its associated health risks in midlife. Moreover, the lack of association between infertility and timing of natural menopause adds to the emerging knowledge that diminishing ovarian reserve does not appear to be a primary biological mechanism of infertility nor its downstream implications for women's health.

STUDY FUNDING/COMPETING INTEREST(S)

Alberta's Tomorrow Project is only possible due to the commitment of its research participants, its staff and its funders: Alberta Health, Alberta Cancer Foundation, Canadian Partnership Against Cancer and Health Canada, and substantial in-kind funding from Alberta Health Services. The views expressed herein represent the views of the author(s) and not of Alberta's Tomorrow Project or any of its funders. This secondary analysis is funded by Project Grant Priority Funding in Women's Health Research from the Canadian Institutes of Health Research (Grant no. 491439). N.V.S. is supported by a Banting Postdoctoral Fellowship from the Canadian Institutes of Health Research. H.K.B. is supported by the Canada Research Chairs Program. E.A.B. is supported by an Early Career Investigator Award in Maternal, Reproductive, Child and Youth Health from the Canadian Institutes of Health Research. A.K.S. has received honoraria from Pfizer, Lupin, Bio-Syent, and Eisai and has received grant funding from Pfizer. N.V.S., H.K.B., and E.A.B. have no conflicts of interest to report.

TRIAL REGISTRATION NUMBER

N/A.

Factors predicting age at menopause among Iranian women in the Bandare-Kong cohort study (a cross-sectional survey of PERSIAN cohort study)

BACKGROUND

Menopause is a natural period in women's life and can be affected by several factors. The aim of this study was to identify the associated factors for age of natural menopause and among women with early and premature menopause based on a cohort study in Iran.

METHODS

This population-based study was conducted on 894 post menopause women between 35 and 70 years old who participated in the Bandare-Kong Non-Communicable Diseases (BKNCD) Cohort Study, a part of Prospective Epidemiological Research Studies in Iran (PERSIAN) from March 2016 to February 2019. All women completed a standard self-reported questionnaire. Data were analyzed using chi-square test, independent t test, and ANOVA as well as a multivariable linear regression model.

RESULTS

The mean age at natural menopause was 48.31 ± 6.34 years. After adjusting other variables, gravida, history of cardiac disease, socioeconomic status and residence status were predictive of age at menopause (P < 0.001). Among the premature menopause group, the mean age at menopause was significantly higher among women with diabetes compared to women without diabetes group (35.68 ± 2.92 vs. 33.82 ± 3.06; P = 0.043), while the mean age at menopause was significantly lower in women with infertility compared to women without infertility (29.13 ± 5.22 vs. 34.84 ± 2.826; P = 0.048).

CONCLUSIONS

This study suggests that the predictors of menopausal age differed in women with premature menopause compared to overall menopause age. Prospective studies are needed to evaluation the effects of these factors on menopausal age.

Practice variation in the stepped care approach to idiopathic heavy menstrual bleeding: A population-based study

INTRODUCTION

Heavy menstrual bleeding (HMB) affects a quarter of all women, with half having no structural cause. Dutch guidelines recommend a stepped care approach to the management of such idiopathic HMB, starting with medication or a levonorgestrel-releasing intrauterine device (LNG-IUD), before progressing to endometrial ablation, and ultimately, hysterectomy. However, practice variation between hospitals could lead to suboptimal health outcomes and increased healthcare costs for some women.

OBJECTIVES

To evaluate adherence to stepped care for women with idiopathic HMB and to identify practice variation among Dutch hospitals.

STUDY DESIGN

This population-based cross-sectional study used Dutch insurance claims data from primary and secondary care for all women with idiopathic HMB referred to a gynecologist between January 2019 and December 2020. We calculated the average number of treatments in the 3 years before each treatment step at each hospital, making adjustments for age, socioeconomic status, and ethnicity. Variation in medical practice was measured by the coefficient of variation (CV).

RESULTS

We studied 20,715 women treated with LNG-IUDs (56%), endometrial ablation (36%), laparoscopic hysterectomy (13%), or vaginal hysterectomy (4%) in 93 hospitals. Before endometrial ablation, on average 47% used medication (hospital range 27%-71%; CV 0.17) and 16% used an LNG-IUD (hospital range 8%-29%, CV 0.32). Before hysterectomy, 52% (hospital range 28%-65%, CV 0.16) used medication, 21% (hospital range 6%-38%, CV 0.35) used an LNG-IUD, and 23% underwent endometrial ablation (hospital range 0%-59%, CV 0.55). On average, women underwent 0.63 (hospital range 0.36-1.00, adjusted rate 0.40-0.98, CV 0.17) and 0.96 (hospital range 0.56-1.45, adjusted rate 0.56-1.44, CV 0.18) treatments before endometrial ablation and hysterectomy, respectively.

CONCLUSIONS

Considerable practice variation exists among Dutch hospitals in the stepped care approach to idiopathic HMB. Improving adherence to this approach could improve quality of care and reduce costs.

Prevalence of early and late menopause and its determinants in Rafsanjan cohort study

Our investigation aimed to evaluate the prevalence of early and late menopause and its determinants in adult women of Rafsanjan cohort study. We used data obtained from the Rafsanjan Cohort Study, as a part of the prospective epidemiological research studies in Iran. In this cross-sectional research, 2002 postmenopausal women were included in the present study. Menopause age were divided into three groups (≤ 41 years, 42-54 years, and ≥ 55 years) based on the 10th and 90th percentile. The association between age at menopause with demographic and reproductive characteristics and some clinical risk factors of women was evaluated by logistic regressions. The mean age at menopause among the study participants was 48.63 ± 5.37 years. In this study, 11.49% and 11.39% of the women experienced early and late menopause respectively. After adjusting for all potential confounders, the results showed that taller and smoker women had higher odds of early menopause (OR 1.03, 95% CI 1.00-1.06) and OR 1.85, 95% CI 1.01-3.41) respectively) and women with history of using hormonal contraceptive more than median had lower odds of early menopause (OR 0.61, 95% CI 0.41-0.91). Also older women (OR 8.65, 95% CI 5.31-14.08) and women with a history of diabetes (OR 2.42, 95% CI 1.63-3.60), hypertension (OR 2.06, 95% CI 1.42-2.97), thyroid disease (OR 1.85, 95% CI 1.07-3.20) and depression (OR 2.00, 95% CI 1.35-2.97) had higher odds of late menopause. The results showed that the year of birth, height, smoking, history of diabetes, hypertension, thyroid disease and depression and using hormonal contraceptive were significantly associated with the menopausal age. Since age at menopause can affect subsequent health in women, understanding the determinants of menopausal age is important and should be pursued.

The association between diabetes type, age of onset, and age at natural menopause: a retrospective cohort study using the Canadian Longitudinal Study on Aging

OBJECTIVES

With growing incidence of type 1 diabetes (T1D), type 2 diabetes (T2D), and gestational diabetes, more women are expected to spend a larger proportion of their reproductive years living with a diabetes diagnosis. It is important to understand the long-term implications of premenopausal diabetes type on women's reproductive health including their age at natural menopause (ANM).

METHODS

Baseline data from the Comprehensive Cohort of Canadian Longitudinal Study on Aging were used. Females who reported premenopausal diagnosis of diabetes were considered exposed. Kaplan-Meier cumulative survivorship estimates and multivariable Cox regression models were used to assess the association between diabetes types and ANM. Sociodemographic, lifestyle, and premenopausal clinical factors were adjusted in the final model as covariates.

RESULTS

The sample comprised 11,436 participants, weighted to represent 1,474,412Canadian females aged 45 to 85 years. The median ANM was 52 years. After adjusting for ethnicity, education, smoking, and premenopausal clinical factors, early age of diagnosis of both T1D (<30 years) and T2D (30-39 years) were associated with earlier menopause (T1D, <30: hazard ratio [HR], 1.55; 95% confidence interval [CI], 1.05-2.28; T2D, 30-39: HR, 1.82; 95% CI, 1.12-2.94), as compared with nondiabetics. In addition, later age of diagnosis of T2D (≥40 years) was associated with later ANM (T2D: HR, 0.63; 95% CI, 0.50-0.80). No significant association between gestational diabetes and ANM was noted.

CONCLUSIONS

Our results point to early menopause among young women living with a diabetes diagnosis. These findings should allow for more focused research geared toward understanding the long-term health implications of diabetes on women's reproductive health and aging.

Impact of modifiable reproductive factors on cancer incidence and mortality in Korea: a systematic review protocol

INTRODUCTION

Cancer is a leading cause of death worldwide. In Korea, it is also a major public health problem. Cancer burden may increase significantly due to ageing population and changes in lifestyle. The features of reproductive factors have changed, which include increased age at first childbirth and decreased breastfeeding duration. This study aims to systematically summarise the association between modifiable reproductive factors and cancer incidence and mortality to provide evidence for planning strategies aimed at reducing cancer incidence and mortality in women.

METHODS AND ANALYSIS

A literature search was performed using the EMBASE, MEDLINE, Cochrane Library and Korean databases such as the Korean Studies Information Service System, Research Information Sharing Service, KoreaMED, Korean Medical Database, National Assembly Library and Korea Institute from their inception to 24 August 2022. We will include cohort studies addressing the associations between at least one of the reproductive factors and the incidence and mortality of all or specific cancers among Korean women. Two reviewers will screen the references, extract the data, and assess the risk of bias independently and in duplicates. Discrepancies will be resolved through discussion or consultation with a third-party reviewer. We will use the Grading of Recommendations, Assessment, Development and Evaluation approach to evaluate the certainty of evidence. We will summarise the findings of the included systematic reviews through quantitative or narrative syntheses and present the summarised findings in tables.

ETHICS AND DISSEMINATION

Ethical approval is not required, since we will use only the published data. We will disseminate the study findings in peer-reviewed publications.

PROSPERO REGISTRATION NUMBER

CRD42022356085.

Life course reproductive dynamics associated with menopause in Ugandan women aged 40-49

BACKGROUND

Early menopausal onset can increase adverse health outcomes in later life; meanwhile, reproductive experiences before menopause may affect its timing. Framed by life course methodology, the study tested for independent and interdependent associations between reproductive history (contraception, age at first birth, parity, terminated pregnancy) and socioeconomic factors (education, wealth, rural-urban residence, cigarette use, marital status, age at first cohabitation) with the occurrence of early menopause.

METHODS

The study population was ever-married women aged 40-49 from the 2016 Demographic & Health Survey (N = 2748). Analytical methods involved probability- and age-adjusted multivariate logistic regression models and predictive margins.

RESULTS

Connections between reproductive and socioeconomic characteristics were key dynamics associated with menopause in ages 40-49. Contraception, parity, and ages at first birth and marriage were found to be independently associated with menopause in this age group. Evidence of interactions was found where no contraceptive use was associated with higher probabilities of menopause for first-time mothers aged 12-15 and for women with no education.

CONCLUSIONS

Studying Ugandan women's reproductive histories highlighted the importance of regional knowledge about menopause. Though we hypothesized that risks would correlate in a chain, the results pointed to risks clustering around contraception, suggesting that improving contraceptive use and education for women could increase menopausal age. Furthermore, the positive association between low parity and early menopause supports the biological mechanism of faster oocyte depletion; however, high-parity populations like Uganda tend to have a younger menopausal age than low-parity populations. Declining mortality in the demographic transition could explain these inverse associations.

Association of lifetime lactation and age at natural menopause: a prospective cohort study

OBJECTIVE

The aim of this study was to examine the association between duration of lifetime lactation and age at natural menopause.

METHODS

In this prospective cohort study, we analyzed parous premenopausal women in the multiethnic Study of Women's Health Across the Nation who were followed approximately annually for 10 years (1995-2008). Lifetime lactation was defined as the duration of breastfeeding across all births in months. Age at natural menopause was defined as age in years after 12 consecutive months of amenorrhea after the final menstrual period for no other reported cause. We used Cox proportional hazard models to analyze time to natural menopause with age as the underlying time scale. Multivariable models controlled for education, race/ethnicity, parity, smoking, body mass index, and oral contraceptive use.

RESULTS

Among 2,377 women, 52.6% experienced natural menopause during follow-up and reported a valid final menstrual period date. The small, crude association between lifetime lactation up to 24 months and later age at natural menopause attenuated to nonsignificance in adjusted models (6 months: adjusted hazard ratio [AHR], 0.96; 95% confidence interval (CI), 0.87-1.06; 12 months: AHR, 0.95; 95% CI, 0.82-1.11; 18 months: AHR, 0.96; 95% CI, 0.82-1.13; 24 months: AHR, 0.99; 95% CI, 0.84-1.16).

CONCLUSIONS

Duration of lifetime lactation was not associated with age at natural menopause after controlling for sociodemographic characteristics.

Primary ovarian cancer after colorectal cancer: a Dutch nationwide population-based study

BACKGROUND AND PURPOSE

Women with colorectal cancer (CRC) are at risk not only of developing ovarian metastases, but also of developing a primary ovarian malignancy. Several earlier studies have in fact shown a link between the development of primary ovarian cancer and CRC. The purpose of this study was therefore to determine the risk of developing a primary ovarian cancer in women with prior CRC compared to the general population.

METHODS

Data from the Netherlands Cancer Registry were used. All women diagnosed with invasive CRC between 1989 and 2017 were included. Standardized incidence ratios (SIRs) and absolute excess risks (AERs) per 10,000 person-years were calculated.

RESULTS

During the study period, 410 (0.3%) CRC patients were diagnosed with primary ovarian cancer. Women with CRC had a 20% increased risk of developing ovarian cancer compared to the general population (SIR = 1.2, 95% CI: 1.1-1.3). The AER of ovarian cancer was 0.9 per 10,000 person-years. The risk was especially increased within the first year of a CRC diagnosis (SIR = 3.3, 95% CI: 2.8-3.8) and in women aged ≤ 55 years (SIR = 2.0, 95% CI: 1.6-2.6).

CONCLUSION

This study found a slightly increased risk of primary ovarian cancer in women diagnosed with CRC compared to the general population. However, this may be partly attributable to surveillance or detection bias. Nevertheless, our findings could be helpful for patient counseling, as CRC patients do not currently receive information concerning the increased risk of ovarian cancer.

Female reproductive life span is extended by targeted removal of fibrotic collagen from the mouse ovary

The female ovary contains a finite number of oocytes, and their release at ovulation becomes sporadic and disordered with aging and with obesity, leading to loss of fertility. Understanding the molecular defects underpinning this pathology is essential as age of childbearing and obesity rates increase globally. We identify that fibrosis within the ovarian stromal compartment is an underlying mechanism responsible for impaired oocyte release, which is initiated by mitochondrial dysfunction leading to diminished bioenergetics, oxidative damage, inflammation, and collagen deposition. Furthermore, antifibrosis drugs (pirfenidone and BGP-15) eliminate fibrotic collagen and restore ovulation in reproductively old and obese mice, in association with dampened M2 macrophage polarization and up-regulated MMP13 protease. This is the first evidence that ovarian fibrosis is reversible and indicates that drugs targeting mitochondrial metabolism may be a viable therapeutic strategy for women with metabolic disorders or advancing age to maintain ovarian function and extend fertility.

The association between reproductive history and menopausal symptoms: an evidence from the cross-sectional survey

Background

During menopause, women experience annoying symptoms which may affect their daily activities and quality of life. This study aimed to determine whether reproductive history, an important indicator of estrogen exposure across the lifetime, is associated with the severity of menopausal symptoms in women.

Methods

This study was a cross-sectional study conducted on 214 women aged 35–65 who were randomly selected, and data was collected by a predesigned structured questionnaire. Each item was graded by subjects and a total score was obtained by summing all subscale scores.

Results

There was a significant association between the somatic, psychological, and urogenital menopausal symptoms and reproductive characteristics. Women with a history of abortion had greater total (β = 0.194, p = 0.009), and psychological (β = 0.230, p = 0.002) symptoms score. Women with higher number of children were more likely to have higher somatic (β = 0.212, p = 0.005) symptoms than others.

Conclusions

Our findings showed reproductive factors may have an influence on the severity of menopausal symptoms. After confirmation by further studies, these findings may help target women at risk of more severe menopausal symptoms at later ages.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-022-01715-z.

The relation of number of childbirths with age at natural menopause: a population study of 310 147 women in Norway

STUDY QUESTION

Does age at natural menopause increase with increasing of number of childbirths?

SUMMARY ANSWER

Age at menopause increased with increasing number of childbirths up to three childbirths; however, we found no further increase in age at menopause beyond three childbirths.

WHAT IS KNOWN ALREADY

Pregnancies interrupt ovulation, and a high number of pregnancies have therefore been assumed to delay menopause. Previous studies have had insufficient statistical power to study women with a high number of childbirths. Thus, the shape of the association of number of childbirths with age at menopause remains unknown.

STUDY DESIGN, SIZE, DURATION

A retrospective population study of 310 147 women in Norway who were 50-69 years old at data collection.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The data were obtained by two self-administered questionnaires completed by women attending BreastScreen Norway, a population-based screening program for breast cancer. The associations of number of childbirths with age at menopause were estimated as hazard ratios by applying Cox proportional hazard models, adjusting for the woman's year of birth, cigarette smoking, educational level, country of birth, oral contraceptive use and body mass index.

MAIN RESULTS AND THE ROLE OF CHANCE

Women with three childbirths had the highest mean age at menopause (51.36 years; 95% CI: 51.33-51.40 years), and women with no childbirths had the lowest (50.55 years; 95% CI: 50.48-50.62 years). Thus, women with no childbirths had higher hazard ratio of reaching menopause compared to women with three childbirths (reference group) (adjusted hazard ratio, 1.24; 95% CI: 1.22-1.27). Beyond three childbirths, we estimated no further increase in age at menopause. These findings were confirmed in sub-analyses among (i) women who had never used hormonal intrauterine device and/or systemic menopausal hormonal therapy; (ii) women who were born before 1950 and (iii) women who were born in 1950 or after.

LIMITATIONS, REASONS FOR CAUTION

Information about age at menopause was based on self-reports.

WIDER IMPLICATIONS OF THE FINDINGS

If pregnancies truly delay menopause, one would expect that women with the highest number of childbirths had the highest age at menopause. Our results question the assumption that interrupted ovulation during pregnancy delays menopause.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the South-Eastern Norway Regional Health Authority [2016112 to M.S.G.] and by the Norwegian Cancer Society [6863294-2015 to E.K.B.]. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Association Between Laparoscopically Confirmed Endometriosis and Risk of Early Natural Menopause

IMPORTANCE

Early natural menopause (ENM) has been associated with reduced reproductive span, cardiovascular disease risk, and early mortality. The potential adverse implications of endometrioma surgery for ovarian reserve are known, yet the association of endometriosis with menopausal timing remains understudied.

OBJECTIVE

To investigate the association between endometriosis and risk for ENM.

DESIGN, SETTING, AND PARTICIPANTS

This large, population-based cohort study analyzed data from the Nurses' Health Study II cohort questionnaires from the 1989 to 2015 questionnaire cycles. The sample included premenopausal women aged 25 to 42 years at baseline or enrollment in 1989. Cumulative follow-up rate was greater than 90%, and participants continued follow-up until the onset of ENM, age 45 years, hysterectomy, oophorectomy, cancer diagnosis, death, loss to follow-up, or end of follow-up in May 2017, whichever occurred first. Data analyses were conducted from October 26, 2020, to April 27, 2021.

EXPOSURES

Endometriosis diagnosis status was queried in the biennial questionnaires, with participants reporting physician diagnosis and whether the diagnosis was laparoscopically confirmed.

MAIN OUTCOMES AND MEASURES

Natural menopause before age 45 years. Menopause status was assessed every 2 years.

RESULTS

The study included 106 633 premenopausal women with a mean (SD) age of 34.8 (4.3) years at baseline, of whom 3921 reported a laparoscopically confirmed endometriosis diagnosis. During 1 508 462 person-years of follow-up, 6640 participants reported being diagnosed with endometriosis, 99 993 never reported endometriosis, and 2542 reported experiencing ENM. In the age- and calendar time-adjusted model, laparoscopically confirmed endometriosis was associated with a 50% greater risk for ENM (hazard ratio [HR], 1.51; 95% CI, 1.30-1.74). A similar risk was observed after adjusting for race and ethnicity and time-varying anthropometric and behavioral factors (HR, 1.46; 95% CI, 1.26-1.69). With additional adjustment for reproductive factors, the HR of ENM was attenuated but significant (HR, 1.28; 95% CI, 1.10-1.48). A greater risk of ENM was observed among women who were nulliparous after stratifying by parity (nulliparous vs parous: HR, 1.46 [95% CI, 1.15-1.86] vs 1.14 [95% CI, 0.94-1.39]; P for heterogeneity = .05) or who never used oral contraceptives when stratifying by oral contraceptive use (never vs ever: HR, 2.03 [95% CI, 1.34-3.06] vs 1.20 [95% CI, 1.02-1.42]; P for heterogeneity = .02). No significant differences were observed in the association between endometriosis and ENM when stratifying by body mass index (calculated as weight in kilograms divided by height in meters squared; <25 vs ≥25: HR, 1.20 [95% CI, 0.99-1.45] vs 1.43 [95% CI, 1.11-1.83; P for heterogeneity = .34), cigarette smoking status (never vs ever: HR, 1.36 [95% CI, 1.13-1.65] vs 1.11 [95% CI, 0.87-1.42]; P for heterogeneity = .57), or history of infertility attributed to ovulatory disorder (no vs yes: HR, 1.28 [95% CI, 1.08-1.51] vs 1.28 [95% CI, 0.90-1.82]; P for heterogeneity = .86).

CONCLUSIONS AND RELEVANCE

This cohort study found a risk for ENM in women with laparoscopically confirmed endometriosis. These women compared with those without endometriosis may be at a higher risk for shortened reproductive duration, particularly those who were nulliparous or never used oral contraceptives.

Ovarian metastases from colorectal cancer in young women: a systematic review of the literature

BACKGROUND AND PURPOSE

In female colorectal cancer patients, a mean proportion of synchronous and/or metachronous ovarian metastases of 3.4% was described. Previous literature showed that young or premenopausal women (≤ 55 years of age) may be more frequently affected. Once ovarian metastases are diagnosed, the prognosis of the patient is generally dismal, with 5-year survival varying from 12 to 27%. The present study is aimed at determining the proportion of young or premenopausal women diagnosed with colorectal cancer who presented with or developed ovarian metastases by reviewing the current literature on this topic.

METHODS

This review was performed by querying MEDLINE and EMBASE databases using a combination of terms: "colorectal neoplasms, colorectal cancer, ovarian neoplasms, Krukenberg tumor, young adult, young age, premenopause." Studies that indicated ovarian metastases, either synchronous or metachronous (or a combination of the two), in young women were retrieved and analyzed.

RESULTS

The review identified 14 studies encompassing 3379 young or premenopausal female colorectal cancer patients. In this selected group of patients, a mean proportion of ovarian metastases of 4.6% [95% CI: 4.0;5.4] was found.

CONCLUSIONS

This review showed that approximately one in twenty young female colorectal cancer patients will present with or develop ovarian metastases. Since outcome of this specific oncological pathology is often dismal, this finding is clinically relevant. It demonstrates the need to develop strategies to lower the incidence of ovarian metastases with adequate treatment and counseling of these patients.

Antral follicle count, oocyte production and embryonic developmental competence of senescent Nellore (Bos indicus) cows

Information on the follicular population and oocyte quality of cows in the final period of reproductive life is scarce. The present study aimed to compare the antral follicle count (AFC), oocyte production and embryonic developmental competence of young versus long-lived and senescent Bos indicus beef cows. Nellore cows (Bos indicus) were classified into three groups according to age: young (4-9 years, n = 10), long-lived (14-17 years, n = 10) and senescent (17-23 years, n = 10). At a random time in the estrus cycle, the cows received cloprostenol sodium salt (0.5 mg, IM), estradiol benzoate (1 mg, IM) and an intravaginal P4 device (1.4 g). Five days later, the P4 devise was removed and oocyte collection (OPU1) was performed. A second OPU (OPU2) was performed 5 days after the first in order to aspirate only growing follicles. During each OPU, AFC and the number and quality of cumulus-oocyte complexes (COCs) were evaluated. Then, the COCs were placed in standard maturation medium (IVM), fertilized and incubated for 9 days. The data were subjected to ANOVA and Multinomial Logistic Regression. The AFC was smaller in long-lived and senescent cows in both OPU1 and OPU2 when compared to younger cows. There was no difference in AFC between OPU1 (19.9 ± 1.8) and OPU2 (17.6 ± 1.9) in young cows, however, more follicles were punctured in long-lived and senescent cows in OPU1 (12.0 ± 2.6 and 19.3 ± 4.6) than in OPU2 (9.2 ± 1.9 and 10.3 ± 2.3), respectively (P < 0.01). The numbers of COCs recovered from young cows (OPU1 = 14.2 ± 1.8; OPU2 = 8.4 ± 0.9) were higher than those obtained from long-lived cows (OPU1 = 5.9 ± 2.3; OPU2 = 4.3 ± 1.0) and senescent cows (OPU1 = 7.2 ± 3.0; OPU2 = 4.1 ± 1.7), respectively (P < 0.05). The cleavage rate did not differ between groups. However, the rate of blastocyst formation was higher for young (64.8%) and long-lived (65.0%) compared to senescent (16.5%) cows (P < 0.01). In conclusion our results indicate that the AFC is lower in long-lived and senescent cows compared with young cows. However, unlike in senescent cows, the embryonic development of long-lived cows is similar to that of young cows. This suggests that Nellore cows aged >17 years begin to have reduced embryonic development capacity due to ovarian aging.

Association of oral contraceptives and tubal ligation with risk of early natural menopause

STUDY QUESTION

What is the association of oral contraceptives (OCs) and tubal ligation (TL) with early natural menopause?

SUMMARY ANSWER

We did not observe an association of OC use with risk of early natural menopause; however, TL was associated with a modestly higher risk.

WHAT IS KNOWN ALREADY

OCs manipulate hormone levels, prevent ovulation, and may modify the rate of follicular atresia, while TL may disrupt the blood supply to the ovaries. These mechanisms may be associated with risk of early menopause, a condition associated with increased risk of cardiovascular disease and other adverse health outcomes.

STUDY DESIGN, SIZE, DURATION

We examined the association of OC use and TL with natural menopause before the age of 45 years in a population-based study within the prospective Nurses' Health Study II (NHSII) cohort. Participants were followed from 1989 to 2017 and response rates were 85-90% for each cycle.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants included 106 633 NHSII members who were premenopausal and aged 25-42 years at baseline. Use, duration and type of OC, and TL were measured at baseline and every 2 years. Menopause status and age were assessed every 2 years. Follow-up continued until early menopause, age 45 years, hysterectomy, oophorectomy, death, cancer diagnosis, or loss to follow-up. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% CIs adjusted for lifestyle, dietary, and reproductive factors.

MAIN RESULTS AND THE ROLE OF CHANCE

Over 1.6 million person-years, 2579 members of the analytic cohort experienced early natural menopause. In multivariable models, the duration, timing, and type of OC use were not associated with risk of early menopause. For example, compared with women who never used OCs, those reporting 120+ months of OC use had an HR for early menopause of 1.01 (95% CI, 0.87-1.17; P for trend=0.71). TL was associated with increased risk of early menopause (HR = 1.17, 95% CI, 1.06-1.28).

LIMITATIONS, REASONS FOR CAUTION

Our study population is homogenous with respect to race and ethnicity. Additional evaluation of these relations in more diverse populations is important.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this is the largest study examining the association of OC use and TL with early natural menopause to date. While TL was associated with a modest higher risk of early menopause, our findings do not support any material hazard or benefit for the use of OCs.

STUDY FUNDING/COMPETING INTEREST(S)

The study was sponsored by UO1CA176726 and R01HD078517 from the National Institutes of Health and Department of Health and Human Services. The work was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. The authors have no competing interests to report.

TRIAL REGISTRATION NUMBER

N/A.

Searching for female reproductive aging and longevity biomarkers

Female reproductive aging is, in a way, a biological phenomenon that develops along canonical molecular pathways; however, it has particular features. Recent studies revealed complexity of the interconnections between reproductive aging and aging of other systems, and even suggested a cause-effect uncertainty between them. It was also shown that reproductive aging can impact aging processes in an organism at the level of cells, tissues, organs, and systems. Women at the end of their reproductive lives are characterized by the accelerated incidence of age-related diseases. Timing of the onset of menarche and menopause and variability in the duration of reproductive life carry a latent social risk: not having enough information about the reproductive potential, women keep on postponing childbirth. Identification and use of the most accurate and sensitive aging biomarkers enable the prediction of menopause timing and quantification of the true biological and reproductive ages of an organism. We discuss current views on reproductive aging and peculiarities of using available biomarkers of aging. We also consider latest advances in the search for potential genetic markers of reproductive aging. Finally, we posit the importance of determining the female biological age and highlight potential research directions in this area.

Genetics of Menopause and Primary Ovarian Insufficiency: Time for a Paradigm Shift?

This review summarizes the existing information concerning the genetic background of menopause and primary ovarian insufficiency (POI). There is overwhelming evidence that majority of genes are involved in double-strand break repair, mismatch repair, and base excision repair. The remaining loci were involved in cell energy metabolism and immune response. Gradual (or in case of rapid POI) accumulation of unrepaired DNA damage causes (premature) cell death and cellular senescence. This in turn leads to exhaustion of cell renewal capacity and cellular dysfunction in affected organs and eventually to aging of the entire soma. Similar erosion of the genome occurs within the germ cell line and the ovaries. Subsequently, the systemic "survival" response intentionally suppresses the sex-steroid hormonal output, which in turn may contribute to the onset of menopause. The latter occurs in particular when age-dependent DNA damage accumulation does not cease. Both effects are expected to synergize to promote (premature) ovarian silencing and install (early) menopause. Consequently, aging of the soma seems to be a primary driver for the loss of ovarian function in women. This challenges the current dogma which implies that loss of ovarian function initiates aging of the soma. It is time for a paradigm shift!

Prevalence and Risk Factors of Premature Ovarian Insufficiency/Early Menopause

Premature ovarian insufficiency (POI) and early menopause, defined as loss of ovarian activity prior to 40 years or menopause between the ages of 40 and 45 years, respectively, is associated with significant adverse health impacts. Recent data indicate that the prevalence of POI and early menopause is greater than was previously thought, affecting more than 10% of women. Biopsychosocial risk factors including genetic, autoimmune, reproductive, lifestyle, early-life, social/environmental, and iatrogenic have been associated with POI/early menopause or earlier age at menopause. However, establishing a causal role and the underlying mechanisms remains elusive. Understanding and clarification of these risk factors will facilitate prevention and risk minimization strategies to optimize women's health.

Factors influencing age at natural menopause

AIM

Women who experience menopause before 45 years, have an increased risk for morbidity and mortality. We aimed to identify the factors influencing the age at natural menopause and to investigate whether tubal ligation alter age at natural menopause.

METHODS

This cross-sectional study was conducted on total 1660 women with natural menopause. The participants were divided into two groups as the ones having menopause before age of 45 years and after 45 years old.

RESULTS

Positive family history, smoking and use of oral contraceptive were found to increase the risk of early menopause by 3.68, 1.34 and 1.04 times, respectively. First pregnancy at older age reduced the risk of early menopause by 0.97 and obesity reduced this risk by 0.65 (95% CI 0.47-0.90). There was no significant difference between menopausal age of patients who underwent BTL (47.46 ± 4.67 years old) and those who did not (47.68 ± 5.18 years old) (P:0.320; P > 0.05). The mean age at menopause of patients who had tubal ligation with laparoscopic cauterization and Pomeroy technique was 46.91 ± 4.07 and 47.55 ± 4.76 years old, respectively (P:0.503; P > 0.05). Besides, there was no significant difference between patients having tubal ligation at the time of cesarean section and those who did not regarding menopausal age (P:0.314; P > 0.05).

CONCLUSION

We recommend identifying modifiable factors and informing women at risk of early menopause. Tubal ligation, when performed correctly, should not compromise ovarian function. If tubal ligation interferes with vascular supply to the ovaries, it may not be substantial enough to result in an earlier onset of menopause.

Association Between Parity and the Age at Menopause and Menopausal Syndrome in Northwest China

This study evaluated the relationships between parity and the age at menopause and menopausal syndrome among Chinese women in Gansu. A total of 7236 women aged 40 to 55 years met study eligibility criteria. The modified Kupperman Menopausal Index scale was used to assess the severity of menopausal syndrome. Cox regression was applied to estimate hazard ratio and 95% confidence interval, and logistic regression was performed to calculate odds ratio and confidence interval. The mean age at menopause was 47.91 ± 3.31 years. There is no relationship between parity and age at menopause. Women with nulliparity or multiparity seemed to have higher risks of moderate and severe menopausal syndrome. The potential beneficial effects of one or two births on menopausal syndrome were also observed by applying the multivariable logistic regression analysis, particularly in urogenital symptoms. Women with nulliparity and multiparity appeared to be at the higher risks of menopause syndrome.

Current Resources for Evidence-Based Practice, July 2020

An extensive review of new resources to support the provision of evidence-based care for women and infants. The current column includes a discussion of whether it is ethical not to offer doula care to all women, and commentaries on reviews focused on folic acid and autism spectrum disorder, and timing of influenza vaccination during pregnancy.

Germline mutation rates in young adults predict longevity and reproductive lifespan

Ageing may be due to mutation accumulation across the lifespan, leading to tissue dysfunction, disease, and death. We tested whether germline autosomal mutation rates in young adults predict their remaining survival, and, for women, their reproductive lifespans. Age-adjusted mutation rates (AAMRs) in 61 women and 61 men from the Utah CEPH (Centre d’Etude du Polymorphisme Humain) families were determined. Age at death, cause of death, all-site cancer incidence, and reproductive histories were provided by the Utah Population Database, Utah Cancer Registry, and Utah Genetic Reference Project. Higher AAMRs were significantly associated with higher all-cause mortality in both sexes combined. Subjects in the top quartile of AAMRs experienced more than twice the mortality of bottom quartile subjects (hazard ratio [HR], 2.07; 95% confidence interval [CI], 1.21–3.56; p = 0.008; median survival difference = 4.7 years). Fertility analyses were restricted to women whose age at last birth (ALB) was ≥ 30 years, the age when fertility begins to decline. Women with higher AAMRs had significantly fewer live births and a younger ALB. Adult germline mutation accumulation rates are established in adolescence, and later menarche in women is associated with delayed mutation accumulation. We conclude that germline mutation rates in healthy young adults may provide a measure of both reproductive and systemic ageing. Puberty may induce the establishment of adult mutation accumulation rates, just when DNA repair systems begin their lifelong decline.

An Appraisal of the Role of Previously Reported Risk Factors in the Age at Menopause Using Mendelian Randomization

Objective

Menopause at a young age is associated with many health problems in women, including osteoporosis, depressive symptoms, coronary disease, and stroke. Many traditional observational studies have reported some potential risk factors for early menopause but have drawn different conclusions. This inconsistency can be attributed mainly to unmodified confounding factors. Identifying the factors causally associated with age at menopause is important for early intervention in women with abnormal menopause timing, and for improving the quality of life for postmenopausal women. This study aims to appraise whether the previously reported risk factors are causally associated with early age at natural menopause (ANM) susceptibility.

Methods

We used Mendelian randomization, a statistical method wherein genetic variants are used to determine whether an observational association between a risk factor and an outcome is consistent with a causal effect.

Results

Women with earlier age at menarche (β = 0.34, se = 0.16, p = 0.035), lower education level (β = 1.19, se = 0.41, p = 0.004) and higher body mass index (β = −0.05, se = 0.02, p = 0.027) had greater risk for early ANM. The causal link between early age at menarche and early ANM was replicated using ReproGen consortium data (β = 0.23, se = 0.07, p = 0.001). However, a current smoking habit, one of previously reported risk factors, was less likely to be correlated causally with early ANM, suggesting that previous observational studies may not have sufficiently adjusted for confounders.

Conclusion

Our results help to identify the risk factors of ANM via a genetics approach and future research into the biological mechanism could further help with targeted prevention for early menopause.