Menstrual and reproductive factors and type 2 diabetes risk: The Japan Public Health Center-based Prospective Study

Reproductive risk factors across the female lifecourse and later metabolic health

Metabolic health is characterized by optimal blood glucose, lipids, cholesterol, blood pressure, and adiposity. Alterations in these characteristics may lead to the development of type 2 diabetes mellitus or dyslipidemia. Recent evidence suggests that female reproductive characteristics may be overlooked as risk factors that contribute to later metabolic dysfunction. These reproductive traits include the age at menarche, menstrual irregularity, the development of polycystic ovary syndrome, gestational weight change, gestational dysglycemia and dyslipidemia, and the severity and timing of menopausal symptoms. These risk factors may themselves be markers of future dysfunction or may be explained by shared underlying etiologies that promote long-term disease development. Disentangling underlying relationships and identifying potentially modifiable characteristics have an important bearing on therapeutic lifestyle modifications that could ease long-term metabolic burden. Further research that better characterizes associations between reproductive characteristics and metabolic health, clarifies underlying etiologies, and identifies indicators for clinical application is warranted in the prevention and management of metabolic dysfunction.

Parity and incident type 2 diabetes in older Chinese women: Guangzhou Biobank Cohort Study

This study examined the association between parity and incident type 2 diabetes in older Chinese women and estimated the mediation effect of adiposity indicators. A total of 11,473 women without diabetes at baseline from 2003 to 2008 were followed up until 2012. We used Cox proportional hazards regression to assess the association between parity and incident type 2 diabetes, and mediation analysis to estimate the mediation effect of adiposity indicators. Compared to women with one parity, the hazard ratio (HR) (95% confidence interval (CI)) for incident type 2 diabetes was 0.85 (0.44-1.63), 1.20 (1.11-1.30), 1.28 (1.16-1.41) and 1.27 (1.14-1.42) for women with parity of 0, 2, 3, and ≥ 4, respectively. The proportion of indirect effect (95% CI) mediated by body mass index, waist circumference, hip circumference, waist-to-hip ratio, waist-to-height ratio and body fat percentage was 26.5% (19.2-52.2%), 54.5% (39.4-108.7%), 25.1% (18.2-49.1%), 35.9% (25.6-74.1%), 50.3% (36.5-98.6%) and 15.1% (- 66.4 to 112.3%), respectively. Compared to women with one parity, women with multiparity (≥ 2) had a higher risk of incident type 2 diabetes and up to half of the association was mediated by abdominal obesity.

Factors Associated with Hemoglobin A1c Level Among Women Without Prior Diabetes Diagnosis in Rural Areas of Central South China: A Cross-Sectional Study

Background

Women in rural areas of China face the unique risk of developing diabetes, but data on the glycemic status among women without prior diabetes diagnosis in rural areas are lacking which may limit the decision-making for diabetes screening or prevention. This study was aimed to describe the glycemic status of women determined by hemoglobin A1c (HbA1c) and explore its associating factors.

Methods

A cross-sectional survey was conducted among women without prior diabetes diagnosis from two counties of rural areas in Central South China from July to October 2018. On the basis of the life course framework, data on socio-demographic, environmental health, genetic, biological (blood pressure, weight and height, lipids), psychosocial, and healthy behavioral factors were collected on site either through questionnaires or field measurements. The questionnaires included social-demographic sheet, Perceived Stress Scale, Self-efficacy scales for health-related diet and exercise behaviors, and Chinese Diabetes Risk Questionnaire. Generalized linear model analysis was performed to determine the associating factors of glycemic status, which was measured by HbA1c level.

Results

A total of 647 women were included in the study. The median age of women was 51.00 years (range 35–65 years). The median HbA1c level was 5.1% (interquartile range 4.6%-5.5%, range 4–13.6%), and 8.7% (n=56) of women were identified as elevated glycemic status (HbA1c>6%). Environmental health factors (eg, living in less-developed county [β=0.206, p=0.027]), biological factors (eg, higher body mass index [β=0.201, p=0.036], higher total cholesterol [β=0.097, p=0.040], history of gestational diabetes mellitus [β=0.722, p<0.001]), and psychosocial factors (eg, higher perceived stress [β=0.247, p=0.002]) were associated with higher HbA1c level.

Conclusion

This study reported 8.7% of elevated glycemic status among women without prior diabetes diagnosis in rural Hunan Province, China. After a comprehensive investigation based on a theoretical framework, living in a less-developed county of rural areas, having larger body mass index, higher total cholesterol, higher perceived stress, and a gestational diabetes mellitus history were identified as associating factors of higher HbA1c level. Professional support regarding weight control, blood lipid control, stress management, and the prevention of gestational diabetes mellitus should be recommended among this population, especially for women from less-developed counties.

Associations of breastfeeding history with metabolic syndrome and cardiovascular risk factors in community-dwelling parous women: The Japan Multi-Institutional Collaborative Cohort Study

OBJECTIVE

The aim of the present study was to investigate the associations between breastfeeding and the prevalence of metabolic syndrome in community-dwelling parous women and to clarify whether the associations depend on age.

METHODS

The present cross-sectional study included 11,118 women, aged 35-69 years. Participants' longest breastfeeding duration for one child and their number of breastfed children were assessed using a self-administered questionnaire, and their total breastfeeding duration was approximated as a product of the number of breastfed children and the longest breastfeeding duration. The longest and the total breastfeeding durations were categorized into none and tertiles above 0 months. Metabolic syndrome and cardiovascular risk factors (obesity, hypertension, dyslipidemia, and hyperglycemia) were defined as primary and secondary outcomes, respectively. Associations between breastfeeding history and metabolic syndrome or each cardiovascular risk factor were assessed using multivariable unconditional logistic regression analysis.

RESULTS

Among a total of 11,118 women, 10,432 (93.8%) had ever breastfed, and 1,236 (11.1%) had metabolic syndrome. In participants aged <55 years, an inverse dose-response relationship was found between the number of breastfed children and the prevalence of metabolic syndrome; multivariable-adjusted odds ratios for 1, 2, 3, and ≥4 breastfed children were 0.60 (95% confidence interval [CI]: 0.31 to 1.17), 0.50 (95% CI: 0.29 to 0.87), 0.44 (95% CI: 0.24 to 0.84), and 0.35 (95% CI: 0.14 to 0.89), respectively. The longest and total breastfeeding durations of longer than 0 months were also associated with lower odds of metabolic syndrome relative to no breastfeeding history in participants aged <55 years. In contrast, all measures of breastfeeding history were not significantly associated with metabolic syndrome and cardiovascular risk factors in participants aged ≥55 years old.

CONCLUSIONS

Breastfeeding history may be related to lower prevalence of metabolic syndrome in middle-aged parous women.

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

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

Associations between parity, pregnancy loss, and breastfeeding duration and risk of maternal type 2 diabetes: An observational cohort study

BACKGROUND

Parity, pregnancy loss, and breastfeeding duration were found to be associated with diabetes. However, the results are inconsistent. Also, no epidemiological studies have examined the association of these reproductive factors with diabetes in the same large population. We aim to investigate the associations between parity, pregnancy loss, breastfeeding duration, and the risk of maternal diabetes in middle-aged and elderly Chinese females.

METHODS

We included 131 174 females aged ≥40 years from the REACTION study (Risk Evaluation of Cancers in Chinese Diabetic Individuals: A Longitudinal Study). Multivariable linear regression and logistic regression were used to assess the association between parity, pregnancy loss, and breastfeeding duration and type 2 diabetes.

RESULTS

The number of parities and breastfeeding duration were positively related to fasting plasma glucose, 2-hour postload glucose, glycosylated hemoglobin, and homeostatic model assessment of insulin resistance. Compared with those with one birth, nulliparous women or women with 2 or ≥3 births had a significantly increased risk of diabetes. The odds ratios (OR) and 95% confidence intervals (CI) were 1.27 (1.10-1.48), 1.17 (1.12-1.22), and 1.28 (1.21-1.35), respectively. Compared with women without pregnancy loss, those who underwent 2 (OR 1.09; 95% CI, 1.04-1.14) or ≥3 pregnancy losses (OR 1.11; 95% CI, 1.04-1.18) had an increased risk of diabetes. Moreover, women with a breastfeeding duration ≥0 to 6 months (OR 0.82; 95% CI, 0.75-0.90) and ≥6 to 12 months (OR 0.94; 95% CI, 0.89-0.99) had a significantly lower risk of diabetes.

CONCLUSIONS

Nulliparous women or women with multiparity or more than one pregnancy loss have an increased risk of diabetes in later life, while women who breastfeed more than 0 to 12 months have a lower risk of diabetes.

The association of parity/live birth number with incident type 2 diabetes among women: over 15 years of follow-up in The Tehran Lipid and Glucose Study

Background

Childbearing may increase the future risk of developing type 2 diabetes mellitus (T2DM) in mothers. However, the issue is not clear completely and not investigated in the Middle East, a region with a high burden of T2DM. In the current study, we examined the association of parity/live birth number with incident T2DM among Iranian women.

Methods

The study population included 2552 women aged 30–65 years recruited in 1999–2001 and were followed for incident T2DM by 3-year intervals. Multivariable Cox proportional hazard models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of the parity/live birth number for incident T2DM. Parity number was defined as the number of live childbirth (number of live birth) plus the number of stillbirth (defined as birth of an infant that died after the 20th week of pregnancy in the uterus).

Results

During a median follow-up of 15.4 years, 557 incident T2DM cases have occurred. After adjustment for potential T2DM risk factors and reproductive factors, each additional parity caused a 9% higher risk for incident T2DM. Moreover, compared to women with one parity, those with 3 and ≥ 4 parity had HRs of 1.73 [95% CI: 1.06–2.83] and 2.23 [1.36–3.65], respectively. After further adjustment for body mass index (BMI) and waist circumference, although the HRs were attenuated prominently, parity ≥ 4 was associated with significantly higher risk (HR: 1.72 [1.05–2.83]); even after further adjustment for triglycerides (TG)/ high-density lipoprotein cholesterol (HDL-C), the risk remained marginally significant (HR: 1.64 [1.00–2.70; P value: 0.051]). For the number of live birth, the results were also similar. Moreover, in a sensitivity analysis, when we considered BMI change during follow-up as another covariate, generally, the effect sizes did not change; the trend of HRs across categories of parity number remained marginally significant (P value: 0.064).

Conclusions

During a long-term follow-up, after adjustment for potential T2DM risk factors, reproductive factors, obesity indices, and TG/HDL-C (insulin resistance surrogate), we demonstrated that higher parity/live birth numbers could be associated with increased risk of T2DM development among Iranian women. Moreover, even after further adjustment for BMI change, the suggestive higher risk was still found.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-021-01519-7.

Menstrual and reproductive factors and limitations in activities of daily living: A case-control study within the Japan Public Health Center-based Prospective Study

AIM

Although menstrual/reproductive factors are known to be associated with physical disability, little is known about these associations in relation to activities of daily living (ADL). This study aimed to clarify associations between menstrual/reproductive factors and ADL limitations in peri- and postmenopausal women.

STUDY DESIGN

A nested case-control study of the Japan Public Health Center-based Prospective (JPHC) Study.

METHODS

The main outcome measure was self-reported ADL levels in the 10-year follow-up questionnaire survey of the JPHC Study conducted between 2000 and 2004 (N = 36 460). Women who "live inside almost independently, but go out with assistance" or had a lower level of activity were considered to have ADL limitations ("cases"), and all others served as controls. Candidate menstrual/reproductive predictors were as follows: menarcheal age, menopausal status, menopausal age, regularity of menses, menstrual cycle, number of pregnancies, age at first pregnancy, number of deliveries, age at first delivery, and breast feeding. Multiple logistic regression analyses were conducted, and odds ratios adjusted for age and past lifestyle were calculated.

RESULTS

Mean ages of cases (N = 592) and controls (N = 38 656) were 68.3 (SD = 7.6) and 61.1 (SD = 7.7) years, respectively. With respect to menopausal age, groups aged <45 and ≥55 years had significantly higher adjusted ORs (1.44, 95% CI: 1.09-1.90 and 1.55, 95%CI: 1.09-2.18, respectively) than the reference group (50-54 years). Multiparous women had significantly lower ORs than nulliparous women.

CONCLUSION

Our findings suggest that menopausal age and parity may predict future ADL limitations in women.

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.

Association of puberty timing with type 2 diabetes: A systematic review and meta-analysis

BACKGROUND

Emerging studies have investigated the association between puberty timing, particularly age at menarche (AAM), and type 2 diabetes. However, whether this association is independent of adiposity is unclear. We aimed to systematically review published evidence on the association between puberty timing and type 2 diabetes (T2D) or impaired glucose tolerance (IGT), with and without adjustment for adiposity, and to estimate the potential contribution of puberty timing to the burden of T2D in the United Kingdom (UK).

METHODS AND FINDINGS

We searched PubMed, Medline, and Embase databases for publications until February 2019 on the timing of any secondary sexual characteristic in boys or girls in relation to T2D/IGT. Inverse-variance-weighted random-effects meta-analysis was used to pool reported estimates, and meta-regression was used to explore sources of heterogeneity. Twenty-eight observational studies were identified. All assessed AAM in women (combined N = 1,228,306); only 1 study additionally included men. In models without adjustment for adult adiposity, T2D/IGT risk was lower per year later AAM (relative risk [RR] = 0.91, 95% CI 0.89-0.93, p < 0.001, 11 estimates, n = 833,529, I2 = 85.4%) and higher for early versus later menarche (RR = 1.39, 95% CI 1.25-1.55, p < 0.001, 23 estimates, n = 1,185,444, I2 = 87.8%). Associations were weaker but still evident in models adjusted for adiposity (AAM: RR = 0.97 per year, 95% CI 0.95-0.98, p < 0.001, 12 estimates, n = 852,268, I2 = 51.8%; early menarche: RR = 1.19, 95% CI 1.11-1.28, p < 0.001, 21 estimates, n = 890,583, I2 = 68.1%). Associations were stronger among white than Asian women, and in populations with earlier average AAM. The estimated population attributable risk of T2D in white UK women due to early menarche unadjusted and adjusted for adiposity was 12.6% (95% CI 11.0-14.3) and 5.1% (95% CI 3.6-6.7), respectively. Findings in this study are limited by residual and unmeasured confounding, and self-reported AAM.

CONCLUSIONS

Earlier AAM is consistently associated with higher T2D/IGT risk, independent of adiposity. More importantly, this research has identified that a substantial proportion of T2D in women is related to early menarche, which would be expected to increase in light of global secular trends towards earlier puberty timing. These findings highlight the need to identify the underlying mechanisms linking early menarche to T2D/IGT risk.