Relationship between alcohol consumption and age at menopause: The Korea National Health and Nutrition Examination Survey

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.

The causal association between smoking initiation, alcohol and coffee consumption, and women's reproductive health: A two-sample Mendelian randomization analysis

Objective: A number of epidemiological studies have demonstrated that smoking initiation and alcohol and coffee consumption were closely related to women's reproductive health. However, there was still insufficient evidence supporting their direct causality effect. Methods: We utilized two-sample Mendelian randomization (TSMR) analysis with summary datasets from genome-wide association study (GWAS) to investigate the causal relationship between smoking initiation, alcohol and coffee consumption, and women's reproductive health-related traits. Exposure genetic instruments were used as variants significantly related to traits. The inverse-variance weighted (IVW) method was used as the main analysis approach, and we also performed MR-PRESSO, MR-Egger, weighted median, and weighted mode to supplement the sensitivity test. Then, the horizontal pleiotropy was detected by using MRE intercept and MR-PRESSO methods, and the heterogeneity was assessed using Cochran's Q statistics. Results: We found evidence that smoking women showed a significant inverse causal association with the sex hormone-binding globulin (SHBG) levels (corrected β = -0.033, p = 9.05E-06) and age at menopause (corrected β = -0.477, p = 6.60E-09) and a potential positive correlation with the total testosterone (TT) levels (corrected β = 0.033, p = 1.01E-02). In addition, there was suggestive evidence for the alcohol drinking effect on the elevated TT levels (corrected β = 0.117, p = 5.93E-03) and earlier age at menopause (corrected β = -0.502, p = 4.14E-02) among women, while coffee consumption might decrease the female SHBG levels (corrected β = -0.034, p = 1.33E-03). Conclusion: Our findings suggested that smoking in women significantly decreased their SHBG concentration, promoted earlier menopause, and possibly reduced the TT levels. Alcohol drinking had a potential effect on female higher TT levels and earlier menopause, while coffee consumption might lead to lower female SHBG levels.

Risk factors for natural menopause before the age of 45: evidence from two British population-based birth cohort studies

Background

Menopause that occurs before the age of 45 and is not medically induced (referred to here as ‘early natural menopause’) affects around one in 10 women and has serious health consequences. These consequences include increased risk of all-cause mortality, cardiovascular disease, osteoporosis, and type 2 diabetes.

Methods

We investigate risk factors for the onset of natural menopause before the age of 45 in two population-based prospective cohort studies in Britain: the 1958 cohort following 8959 women and the 1970 cohort following 8655 women. These studies follow women from birth to adulthood, and we use harmonized data on birth and early life characteristics, reproductive health, health behaviour, and socioeconomic characteristics for 6805 women who were pre-menopausal, peri-menopausal or had undergone natural menopause. Of these 6805 women, 3614 participated in the 1958 cohort (of which 368 had early menopause) and 3191 participated in the 1970 cohort (of which 206 had early menopause). Taking a life course approach, we focus on three distinct life stages - birth/early life, childhood, and early adulthood - to understand when risk factors are most harmful. Respecting the temporal sequence of exposures, we use a series of multivariable logistic regression models to estimate associations between early menopause and each potential risk factor adjusted for confounders.

Results

We find that early menopause is influenced by circumstances at birth. Women born in lower social class families, whose mother smoked during the pregnancy or who were breastfed 1 month or less were more likely to undergo early menopause. Early menopause is also associated with poorer cognitive ability and smoking in childhood. Adult health behaviour also matters. Smoking is positively correlated with early menopause, while regular exercise and moderate frequency of alcohol drinking in women’s early thirties are associated with reduced risk of early menopause. The occurrence of gynaecological problems by women’s early thirties is also linked to early menopause.

Conclusions

We demonstrate that characteristics at different periods of life are associated with early menopause. Some of these associations relate to modifiable behaviours and thus the risks of early menopause and the adverse health outcomes associated with it may be preventable.

Association of weight, smoking, and alcohol consumption with age at natural menopause

In South Korea, rapid economic growth and modernization have led to changes in lifestyle factors that may affect age at natural menopause. Data from 4,793 women aged ≥55 years, who had a natural menopause, were analyzed from the Korea National Health and Nutrition Examination Survey (2013-2017). Multinomial logistic regression was used to examine the association between lifestyle factors and age at natural menopause after adjusting for birth cohort (Model 1) and sociodemographic and reproductive factors (Model 2). Overall, 3.1% of women experienced premature menopause (<40 years), 7.6% early menopause (40-44 years), and 12.8% late menopause (≥55 years). Women born in the 1940s or earlier among the birth cohorts had the highest prevalence of premature (70.0%), early (58.5%), and late (43.1%) menopause. In Model 2, current smoking (odds ratio = 3.99 and 95% confidence interval = 1.35-11.81) was associated with premature menopause. Low (<18.5 kg/m²) and high (≥25 kg/m²) body mass index were associated with early (odds ratio = 2.30 and 95% confidence interval = 1.01-5.22) and late (odds ratio = 1.38 and 95% confidence interval = 1.10-1.72) menopause respectively. Conversely, there was no association between age at natural menopause and alcohol consumption. The results suggest that healthy lifestyle factors, such as not smoking and proper weight maintenance, are significant factors affecting age at natural menopause. Our findings may help develop health policies and provide targeted care to improve women's health after midlife.

Premature menopause among women in India: Evidence from National Family Health Survey-IV

AIM

Women who experience premature menopause either due to biological or induced reasons have a longer duration of exposure to severe symptoms and adverse health consequences when compared to those who undergo menopause at later age. Despite the fact that premature menopause has a profound effect on the health of women, there has been limited study on this issue. Therefore, this study attempted to determine the prevalence and factors associated with premature menopause among 302 557 women aged 25-39 years in India.

METHODS

This study utilized secondary data from the fourth round of the National Family Health Survey-IV (NFHS-4), conducted during 2015-2016 in India. Descriptive statistics and multinomial logistic regression were used for statistical analyses of the data.

RESULTS

The results revealed that the prevalence of premature menopause in this sample of Indian women was 3.7%, out of which 2.1% of women had experienced natural premature menopause, whereas 1.7% had surgical premature menopause. The prevalence of premature menopause was highest in the southern region of India. Factors like age, education, wealth index, place of residence, smoking status, children ever born, age at first birth, use of hormonal contraception, sterilization, and body mass index were found to be associated with premature menopause in India.

CONCLUSION

A sizeable proportion of women in India are attaining menopause prematurely. Furthermore, the percentage and likelihood of experiencing premature menopause are relatively high among rural women, women with higher parity, early age at childbearing, and women who smoke.

The role of age at menarche and age at menopause in Alzheimer's disease: evidence from a bidirectional mendelian randomization study

The association between endogenous estrogen exposure and Alzheimer's disease (AD) remains inconclusive in previous observational studies, and few Mendelian randomization (MR) studies have focused on their causality thus far. We performed a bidirectional MR study to clarify the causality and causal direction of age at menarche and age at menopause, which are indicators of endogenous estrogen exposure, on AD risk. We obtained all genetic datasets for the MR analyses using publicly available summary statistics based on individuals of European ancestry from the IEU GWAS database. The MR analyses indicated no significant causal relationship between the genetically determined age at menarche (outlier-adjusted inverse variance weighted odds ratio [IVWOR] = 0.926; 95% confidence interval [CI], 0.803-1.066) or age at menopause (outlier-adjusted IVWOR = 0.981; 95% CI, 0.941-1.022) and AD risk. Similarly, AD did not show any causal association with age at menarche or age at menopause. The sensitivity analyses yielded similar results. In contrast, an inverse association was detected between age at menarche and body mass index (BMI, outlier-adjusted IVW β = -0.043; 95% CI, -0.077 to -0.009). Our bidirectional MR study provides no evidence for a causal relationship between the genetically determined age at menarche or age at menopause and AD susceptibility, or vice versa. However, earlier menarche might be associated with higher adult BMI.

Effects of Environment and Lifestyle Factors on Premature Ovarian Failure

Premature ovarian insufficiency (POI) or primary ovarian failure is defined as a cessation of the menstrual cycle in women younger than 40 years old. It is strictly defined as more than 4 months of oligomenorrhea or amenorrhea in a woman <40 years old, associated with at least two follicle-stimulating hormone (FSH) levels >25 U/L in the menopausal range, detected more than 4 weeks apart. It is estimated that POI was affected 1 and 2% of women. Although 80% of POI cases are of unknown etiology, it is suggested that genetic disorder, autoimmune origin, toxins, and environmental factors, as well as personal lifestyles, may be risk factors of developing POI. In this section, we will discuss the influences of environmental and lifestyle factors on POI. Moreover updated basic research findings regarding how these environmental factors affect female ovarian function via epigenetic regulations will also be discussed.