Natural fertility and longevity

Late reproduction is associated with extended female survival but not with familial longevity

RESEARCH QUESTION

Are age at last childbirth and number of children, as facets of female reproductive health, related to individual lifespan or familial longevity?

DESIGN

This observational study included 10,255 female participants from a multigenerational historical cohort, the LINKing System for historical family reconstruction (LINKS), and 1258 female participants from 651 long-lived families in the Leiden Longevity Study (LLS). Age at last childbirth and number of children, as outcomes of reproductive success, were compared with individual and familial longevity using the LINKS dataset. In addition, the genetic predisposition in the form of a polygenic risk score (PRS) for age at menopause was studied in relation to familial longevity using the LLS dataset.

RESULTS

For each year increase in the age of the birth of the last child, a woman's lifespan increased by 0.06 years (22 days; P = 0.002). The yearly risk for having a last child was 9% lower in women who survived to the oldest 10% of their birth cohort (hazard ratio 0.91, 95% CI 0.86-0.95). Women who came from long-living families did not have a higher mean age of last childbirth. There was no significant association between familial longevity and genetic predisposition to age at menopause.

CONCLUSIONS

Female reproductive health associates with a longer lifespan. Familial longevity does not associate to extended reproductive health. Other factors in somatic maintenance that support a longer lifespan are likely to have an impact on reproductive health.

Di(2-ethylhexyl) phthalate induces reproductive toxicity and transgenerational reproductive aging in Caenorhabditis elegans

With the large-scale production and use of plastic products, the global plastic pollution problem is becoming more and more serious. The plasticizer di (2-ethylhexyl) phthalate (DEHP), which is widely used in the production of plastics, has caused great concern for the health of the population. Exposure of organisms to DEHP can cause a variety of health damage, of which reproductive system damage is an important part. At present, there are still few studies on DEHP in reproductive aging, and it is of great significance to explore the role of DEHP in promoting reproductive aging and its underlying mechanism. In this study, the model organism Caenorhabditis elegans (C. elegans) was used to preliminarily explore the mechanism of DEHP-induced female reproductive senescence. The results showed that DEHP reduced the number of offspring and gonad area of C. elegans, resulting in shortened reproductive and life span, abnormal phenotypes in somatic gonad structure including the Emo phenotype, the BOW phenotype, a twisted gonad arm, and atrophied oocytes. Biochemical studies showed that DEHP promoted oxidative stress and autophagy in C. elegans. Further, we found the decreased number of offspring, malformed somatic gonad structure, oxidative damage and autophagy induced by DEHP in parental worms can be inheritance to the not directly exposed offspring.

Are pregnancy and parity associated with telomere length? A systematic review

BACKGROUND

Women's reproduction requires increased energy demands, which consequently may lead to cellular damage and aging. Hence, Telomere Length (TL), a biomarker of biological aging and health status may possibly serve as a biomarker of reproductive effort. The aim of this systematic review is to evaluate telomere dynamics throughout pregnancy and the association between parity and TL.

METHODS

A systematic search was conducted across seven databases including CINAHL, Cochrane, PsycINFO, Proquest, PubMed; Scopus; and Web of Science, using keywords and MeSH descriptors of parity and TL. Predefined inclusion and exclusion criteria were used to screen abstracts and titles. After the removal of duplicates, 3431 articles were included in the primary screening, narrowed to 194 articles included in the full-text screening. Consensus was reached for the 14 studies that were included in the final review, and the Newcastle-Ottawa scale (NOS) was utilized to assess the quality of the selected studies. A mini meta-analysis utilized JASP 0.17.3 software and included 4 applicable studies, comprising a total of 2564 participants to quantitatively assess the estimated effect size of parity on TL.

RESULTS

Of the 11 studies reviewed on parity and TL, four demonstrated a negative correlation; one - a positive correlation and six -found no correlation. Studies demonstrating a negative correlation encompassed rigorous methodological practices possibly suggesting having more children is associated with enhanced telomere attrition. Of the four longitudinal studies assessing telomere dynamics throughout pregnancy, most found no change in TL from early pregnancy to postpartum suggesting pregnancy does not affect TL from early pregnancy to early postpartum. The meta-analysis revealed a negative, yet, non-significant effect, of the estimated effect size of parity on TL(ES = -0.009, p = 0.126, CI -0.021, 0.03).

CONCLUSIONS

Studies assessing pregnancy, parity and TL yielded mixed results, most likely due to the different research methods utilized in each study. Improvements in study design to better understand the short-term effects of pregnancy on TL and the effect of parity on TL over time, include precise definitions of parity, comparisons of different age groups, inclusion of reproductive lifespan and statistically adjusting for potential confounders in the parity and TL relationship.

Pregnancy-induced physiological hypertrophic preconditioning attenuates pathological myocardial hypertrophy by activation of FoxO3a

Previous studies show a woman's pregnancy is correlated with post-reproductive longevity, and nulliparity is associated with higher risk of incident heart failure, suggesting pregnancy likely exerts a cardioprotection. We previously reported a cardioprotective phenomenon termed myocardial hypertrophic preconditioning, but it is unknown whether pregnancy-induced physiological hypertrophic preconditioning (PHP) can also protect the heart against subsequent pathological hypertrophic stress. We aimed to clarify the phenomenon of PHP and its mechanisms. The pluripara mice whose pregnancy-induced physiological hypertrophy regressed and the nulliparous mice underwent angiotensin II (Ang II) infusion or transverse aortic constriction (TAC). Echocardiography, invasive left ventricular hemodynamic measurement and histological analysis were used to evaluate cardiac remodeling and function. Silencing or overexpression of Foxo3 by adeno-associated virus was used to investigate the role of FoxO3a involved in the antihypertrophic effect. Compared with nulliparous mice, pathological cardiac hypertrophy induced by Ang II infusion, or TAC was significantly attenuated and heart failure induced by TAC was markedly improved in mice with PHP. Activation of FoxO3a was significantly enhanced in the hearts of postpartum mice. FoxO3a inhibited myocardial hypertrophy by suppressing signaling pathway of phosphorylated glycogen synthase kinase-3β (p-GSK3β)/β-catenin/Cyclin D1. Silencing or overexpression of Foxo3 attenuated or enhanced the anti-hypertrophic effect of PHP in mice with pathological stimulation. Our findings demonstrate that PHP confers resistance to subsequent hypertrophic stress and slows progression to heart failure through activation of FoxO3a/GSK3β pathway.

Maternal age at birth of last child and cardiovascular disease mortality later in life among a national cohort of postmenopausal women from the United States

Maternal age at last birth of child is increasing in the United States, and it has been reported to influence future chronic diseases. In this study of nationally-representative sample of postmenopausal women, there was no conclusive association between maternal age at last birth of child and cardiovascular disease mortality later in life.

Objective

Maternal age at last birth (ALB) of child is increasing in the United States, and it has been reported to influence future chronic diseases. However, the relationship of ALB and cardiovascular disease (CVD) events later in life has not been widely studied. We evaluated the association of ALB with CVD mortality.

Methods

Data were from 7,971 parous postmenopausal women older than 45 years who participated in the US National Health and Nutritional Examination Survey from 1999 to 2018 and had mortality follow-up data through to December 31, 2019. ALB was self-reported, whereas CVD mortality was assessed using International Classification of Diseases codes. Cox regression was used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI).

Results

The mean age of participants was 63 ± 9.8 years, with 9.5% being non-Hispanic Black, 9.7% being Hispanic women, and 21% reporting ALB ≥35 years. During a median follow-up of 8.1 years, 443 participants died from CVD. In age-adjusted models, CVD mortality was elevated for women with ALB of <25 years (HR, 1.68; 95% CI, 1.23-2.29) and ALB of ≥35 years (HR, 1.37; 95% CI, 1.00-1.88). However, after additional adjustment for race and ethnicity, foreign born, education, marital status, poverty income ratio, parity, smoking status, age at menarche, oral contraceptive pills use and family history of myocardial infarction, these estimates were attenuated resulting in no association between ALB and CVD mortality.

Conclusions

In this study of nationally representative sample of postmenopausal women, there was no conclusive association between maternal ALB and CVD mortality later in life.

Is Aging an Inevitable Characteristic of Organic Life or an Evolutionary Adaptation?

Aging is an evolutionary paradox. Several hypotheses have been proposed to explain it, but none fully explains all the biochemical and ecologic data accumulated over decades of research. We suggest that senescence is a primitive immune strategy which acts to protect an individual's kin from chronic infections. Older organisms are exposed to pathogens for a longer period of time and have a higher likelihood of acquiring infectious diseases. Accordingly, the parasitic load in aged individuals is higher than in younger ones. Given that the probability of pathogen transmission is higher within the kin, the inclusive fitness cost of infection might exceed the benefit of living longer. In this case, programmed lifespan termination might be an evolutionarily stable strategy. Here, we discuss the classical evolutionary hypotheses of aging and compare them with the pathogen control hypothesis, discuss the consistency of these hypotheses with existing empirical data, and present a revised conceptual framework to understand the evolution of aging.

Impact of fertility on the longevity of older rural Chinese women: an analysis of a longitudinal survey

Background

This study evaluates the impact of fertility during the childbearing period on the longevity of older rural Chinese women and verifies whether any trade-off exists between women’s longevity and their number of children to provide empirical evidence for improving health intervention policies and formulating active fertility policies in low-fertility countries.

Methods

Based on the data of the deaths of 1623 older adults aged 65 and above during 2014–2018 in the Chinese Longitudinal Healthy Longevity Survey, this study explores the relationship between the number of children born and older rural women’s longevity using the ordinary least squares method. Furthermore, the impact of fertility on the longevity of men and women in rural and urban areas, along with other reproductive behaviours on older rural women’s longevity, were analysed.

Results

There was a significant negative correlation between the number of children born and women’s longevity (β = − 0.555, p < 0.05). Additionally, their longevity exhibited a decreasing trend with having birthed more sons and an increasing trend with more daughters. Age at first and last births had a significant positive relationship with rural women’s longevity; however, the effect of fertility on the longevity of older rural and urban men and older urban women was not significant.

Conclusions

It is confirmed that there is a trade-off between fertility and longevity for rural women in China. Future research should focus on compensating for the decline in female longevity caused by the number of children born and promote the concept of a healthy pregnancy, scientific nurture, and gender equality in fertility.

Leukocyte Telomere Length Correlates with Extended Female Fertility

Current social trends of delayed reproduction to the fourth and fifth decade of life call for a better understanding of reproductive aging. Demographic studies correlated late reproduction with general health and longevity. Telomeres, the protective ends of eukaryotic chromosomes, were implicated in various aging-associated pathologies and longevity. To examine whether telomeres are also associated with reproductive aging, we measured by Southern analysis the terminal restriction fragments (TRF) in leukocytes of women delivering a healthy infant following a spontaneous pregnancy at 43–48 years of age. We compared them to age-matched previously fertile women who failed to conceive above age 41. The average TRF length in the extended fertility group (9350 bp) was significantly longer than in the normal fertility group (8850 bp; p-value = 0.03). Strikingly, excluding women with nine or more children increased the difference between the groups to over 1000 bp (9920 and 8880 bp; p-value = 0.0009). Nevertheless, we observed no apparent effects of pregnancy, delivery, or parity on telomere length. We propose that longer leukocyte telomere length reflects higher oocyte quality, which can compensate for other limiting physiological and behavioral factors and enable successful reproduction. Leukocyte telomere length should be further explored as a novel biomarker of oocyte quality for assessing reproductive potential and integrating family planning with demanding women’s careers.

The Influence of Female Reproductive Factors on Longevity: A Systematized Narrative Review of Epidemiological Studies

Purpose: This systematized review presents a synthesis of epidemiological studies that examine the association between female reproductive factors and longevity indicators. Methods: A comprehensive literature search was conducted using four bibliographic databases: OVID Medline, Web of Science, PubMed, and Google Scholar, including English language articles published until March 2022. Results from the search strategy yielded 306 articles, 37 of which were included for review based on eligibility criteria. Results were identified within the following nine themes: endogenous androgens and estrogens, age at first childbirth, age at last childbirth, parity, reproductive lifespan, menopause-related factors, hormone therapy use, age at menarche, and offspring gender. Results: Evidence that links reproductive factors and long lifespan is limited. Several female reproductive factors are shown to be significantly associated with longevity, yet findings remain inconclusive. The most consistent association was between parity (fertility and fecundity) and increased female lifespan. Age at first birth and parity were consistently associated with increased longevity. Associations between age at menarche and menopause, premature menopause, reproductive lifespan, offspring gender and longevity are inconclusive. Conclusion: There is not enough evidence to consider sex a longevity predictor. To understand the mechanisms that predict longevity outcomes, it is imperative to consider sex-specific within-population differences.

Clinical investigation of fertility after uterine artery embolization

BACKGROUND

Uterine artery embolization is an effective and safe technique for the treatment of uterine fibroids, but its use remains controversial for women who wish to procreate.

OBJECTIVE

This study aimed to study the clinical, anatomic, and obstetrical results of uterine artery embolization in patients of childbearing age not eligible for myomectomy.

STUDY DESIGN

This was a retrospective cohort study of 398 female patients under the age of 43 years who were treated by uterine artery embolization between 2003 and 2017 for symptomatic fibroids and/or adenomyosis. Uterine artery embolization was performed according to a standardized procedure (fertility-sparing uterine artery embolization technique), with ovarian protection in the event of dangerous utero-ovarian anastomosis. Magnetic resonance imaging and pelvic ultrasounds were performed before and after uterine artery embolization.

RESULTS

The overall clinical success rate (ie, resolution of preembolization symptoms such as heavy menstrual bleeding, iron-deficiency anemia, pelvic pressure) was 91.2%, and there were no major complications. One year after uterine artery embolization, we observed a mean 73% reduction in myoma volume. A total of 108 patients (49.3%) presented with dangerous utero-ovarian anastomosis and 33 (14.5%) benefited from ovarian protection. In our group, there were 148 pregnancies and 109 live births; 74 children were born at term; 23 were born preterm, on average at 35.12±2.78 weeks. Including preterm births, the mean birthweight and birth length of the children were within normal limits. Restoration of uterine anatomy and ovarian protection were identified as the main predictive factors for obstetrical success. Restoration was also a major predictive factor for clinical success and was associated with a lower rate of miscarriage.

CONCLUSION

This study provided detailed clinical and obstetrical outcomes for 398 female patients who underwent uterine artery embolization for fibroid treatment; it contributes to the identification of anatomic and technical factors that could have an impact on fertility after uterine artery embolization. Further controlled clinical trials are needed to confirm our findings and reevaluate this procedure's indications and limitations for women with a desire to procreate.

Examining the trade-offs between human fertility and longevity over three centuries using crowdsourced genealogy data

The evolution theory of ageing predicts that reproduction comes with long-term costs of survival. However, empirical studies in human species report mixed findings of the relationship between fertility and longevity, which varies by populations, time periods, and individual characteristics. One explanation underscores that changes in survival conditions over historical periods can moderate the negative effect of human fertility on longevity. This study investigates the fertility-longevity relationship in Europe during a period of rapid modernisation (seventeenth to twentieth centuries) and emphasises the dynamics across generations. Using a crowdsourced genealogy dataset from the FamiLinx project, our sample consists of 81,924 women and 103,642 men born between 1601 and 1910 across 16 European countries. Results from multilevel analyses show that higher fertility has a significantly negative effect on longevity. For both women and men, the negative effects are stronger among the older cohorts and have reduced over time. Moreover, we find similar trends in the dynamic associations between fertility and longevity across four geographical regions in Europe. Findings and limitations of this study call for further investigations into the historical dynamics of multiple mechanisms behind the human evolution of ageing.

Inflammaging: Blame the sons. Relationships between the number of sons and the level of inflammatory mediators among post-reproductive women

OBJECTIVES

Reproduction is costly, but sons and daughters differently influence maternal physiology, also in older age. In particular, having sons may negatively influence maternal health and may be associated with a shorter life span of mothers. Sons may also contribute to increased inflammaging, a chronic sub-clinical systemic inflammatory state characterized by elevated levels of serum inflammatory mediators. The aim of this study was to examine the impact of the total number of children, and the number of daughters and sons separately on concentrations of C-reactive protein (CRP), and proinflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α).

MATERIALS AND METHODS

The participants were 378 women aged 45-92 who had 3.9 (SD 2.12, median = 4, range = 0-13) children, including 2.1 (SD 1.46, median = 2, range = 0-8) sons and 1.8 (SD 1.44, median = 2, range = 0-7) daughters on average.

RESULTS

We found a positive relationship between the overall number of children and IL-6 levels. CRP and IL-6 concentrations were positively associated with the number of sons but not with the number of daughters. Each son increased maternal CRP level by 11%, and IL-6 level by 6%. Neither the total number of children nor the number of daughters or sons were related to the TNF-α concentration.

DISCUSSION

Aging-associated inflammation in post-reproductive mothers with a higher number of sons supports the hypothesis of trade-offs between reproduction and health. Furthermore, these results provide new evidence contributing to the idea that having sons may have more detrimental effects on the maternal organism than having daughters.

Early ovarian ageing: is a low number of oocytes harvested in young women associated with an earlier and increased risk of age-related diseases?

STUDY QUESTION

Do young women with early ovarian ageing (EOA), defined as unexplained, and repeatedly few oocytes harvested in ART have an increased risk of age-related events?

SUMMARY ANSWER

At follow-up, women with idiopathic EOA had an increased risk of age-related events compared to women with normal ovarian ageing (NOA).

WHAT IS KNOWN ALREADY

Early and premature menopause is associated with an increased risk of cardiovascular diseases (CVDs), osteoporosis and death. In young women, repeated harvest of few oocytes in well-stimulated ART cycles is a likely predictor of advanced menopausal age and may thus serve as an early marker of accelerated general ageing.

STUDY DESIGN, SIZE, DURATION

A register-based national, historical cohort study. Young women (≤37 years) having their first ART treatment in a public or private fertility clinic during the period 1995-2014 were divided into two groups depending on ovarian reserve status: EOA (n = 1222) and NOA (n = 16 385). Several national registers were applied to assess morbidity and mortality.

PARTICIPANTS/MATERIALS, SETTING, METHODS

EOA was defined as ≤5 oocytes harvested in a minimum of two FSH-stimulated cycles and NOA as ≥8 oocytes in at least one cycle. Cases with known causes influencing the ovarian reserve (endometriosis, ovarian surgery, polycystic ovary syndrome, chemotherapy etc.) were excluded. To investigate for early signs of ageing, primary outcome was an overall risk of ageing-related events, defined as a diagnosis of either CVD, osteoporosis, type 2 diabetes, cancer, cataract, Alzheimer's or Parkinson's disease, by death of any-cause as well as a Charlson comorbidity index score of ≥1 or by registration of early retirement benefit. Cox regression models were used to assess the risk of these events. Exposure status was defined 1 year after the first ART cycle to assure reliable classification, and time-to-event was measured from that time point.

MAIN RESULTS AND THE ROLE OF CHANCE

Median follow-up time from baseline to first event was 4.9 years (10/90 percentile 0.7/11.8) and 6.4 years (1.1/13.3) in the EOA and NOA group, respectively. Women with EOA had an increased risk of ageing-related events when compared to women with a normal oocyte yield (adjusted hazard ratio 1.24, 95% CI 1.08 to 1.43). Stratifying on categories, the EOA group had a significantly increased risk for CVD (1.44, 1.19 to 1.75) and osteoporosis (2.45, 1.59 to 3.90). Charlson comorbidity index (1.15, 0.93 to 1.41) and early retirement benefit (1.21, 0.80 to 1.83) was also increased, although not reaching statistical significance.

LIMITATIONS, REASONS FOR CAUTION

Cycles never reaching oocyte aspiration were left out of account in the inclusion process and we may therefore have missed women with the most severe forms of EOA. We had no information on the total doses of gonadotrophin administered in each cycle.

WIDER IMPLICATIONS OF THE FINDINGS

These findings indicate that oocyte yield may serve as marker of later accelerated ageing when, unexpectedly, repeatedly few oocytes are harvested in young women. Counselling on life-style factors as a prophylactic effort against cardiovascular and other age-related diseases may be essential for this group of women.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was received for this study. All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Costs of reproduction and ageing in the human female

Evolutionary theories of ageing point to reproduction as a significant factor to consider when asking why ageing occurs and why there is inter-individual variation in its progression. Reproduction in human females is costly, in terms of energy, nutrients and metabolic adjustments. Thus, it is expected that women who experienced high reproductive effort resulting from multiple reproductive events will age faster. However, the evidence for long-term negative effects of reproduction is not conclusive. The lack of understanding of whether there are trade-offs between reproduction and ageing in women is partly due to methodological challenges. The costs of reproduction are often calculated based only on parity, while other elements contributing to these costs (e.g. breastfeeding, timing of reproduction) are neglected, which may significantly underestimate the total costs and obscure the all-important inter-individual variation in such costs. Costs must be evaluated in relation to individual characteristics, including developmental conditions, nutritional status and social support that a mother receives during reproduction. Furthermore, ageing and health must be assessed based on comprehensive markers rather than arbitrarily assembled variables. Finally, longitudinal rather than cross-sectional studies and new statistical approaches are needed to reveal how much of a decline in health and progressing ageing can actually be attributed to past reproductive processes. This article is part of the theme issue 'Evolution of the primate ageing process'.

CREB Non-autonomously Controls Reproductive Aging through Hedgehog/Patched Signaling

Evolutionarily conserved signaling pathways are crucial for adjusting growth, reproduction, and cell maintenance in response to altered environmental conditions or energy balance. However, we have an incomplete understanding of the signaling networks and mechanistic changes that coordinate physiological changes across tissues. We found that loss of the cAMP response element-binding protein (CREB) transcription factor significantly slows Caenorhabditis elegans' reproductive decline, an early hallmark of aging in many animals. Our results indicate that CREB acts downstream of the transforming growth factor β (TGF-β) Sma/Mab pathway in the hypodermis to control reproductive aging, and that it does so by regulating a Hedgehog-related signaling factor, WRT-10. Overexpression of hypodermal wrt-10 is sufficient to delay reproductive decline and oocyte quality deterioration, potentially acting via Patched-related receptors in the germline. This TGF-β-CREB-Hedgehog signaling axis allows a key metabolic tissue to communicate with the reproductive system to regulate oocyte quality and the rate of reproductive decline.

Female Fertility Has a Negative Relationship With Longevity in Chinese Oldest-Old Population: A Cross-Sectional Study

BACKGROUND

Despite research efforts in this field for more than a century, the relationship between female fertility and longevity is unclear. This study was designed to investigate this relationship in Chinese oldest-old population.

METHODS

The China Hainan Centenarian Cohort Study was performed in 18 cities and counties of Hainan. A total of 1,226 females, including 758 centenarian women and 468 women aged 80-99 years, were enrolled in this study. Using a standardized protocol, in-person interviews and blood analyses were conducted by a well-trained research team through home visits.

RESULTS

Centenarian women had significantly lower number of children (NOC) and higher initial childbearing age (ICA) and last childbearing age (LCA) than women aged 80-99 years (p < 0.05 for all). Multivariate logistic regression analysis showed that NOC and testosterone (T) levels were positively associated with women aged 80-99 years, when centenarian women was considered as reference (p < 0.05 for all). ICA, LCA, and estradiol (E2) levels were negatively associated with women aged 80-99 years, when centenarian women was considered as reference (p < 0.05 for all).

CONCLUSIONS

The centenarians had crucial characteristics of less and delayed childbearing, indicating a negative relationship between female fertility and longevity in Chinese oldest-old population. Serum E2 levels were positively associated and serum T levels were negatively associated with longevity. The less and late childbearing might be a significant factor of longevity, and successful aging might be promoted by reducing and delaying female childbearing.

The Differential Impact of Religion on Self-Reported Health Among Serbian Roma Women

The present paper offers an account of how self-reported health varies with religious affiliation and reproductive effort among Serbian Roma women. Data were collected in 2014-2018 in two Roma semi-urban settlements in central Serbia. The sample consisted of 177 Christian and 127 Muslim women, averaging 54 years of age. In addition to religious affiliation (Christianity/Islam), demographic data, reproductive histories, data on self-reported and children's health were collected, along with height and weight, and smoking status. Christian and Muslim Roma women differed significantly on a number of variables, with Muslim women reporting poorer health and higher reproductive effort. Among Roma women religion may be an important determinant of reproductive and fertility patterns, largely because it may have formed an important foundation upon which identity is based. This study adds to the literature on the cross-cultural relevance of the ways religion shapes reproductive behaviors for understanding the health variations of women from the same ethnic group who profess different religions.

Impact of demography and population dynamics on the genetic architecture of human longevity

The study of the genetics of longevity has been mainly addressed by GWASs that considered subjects from different populations to reach higher statistical power. The "price to pay" is that population-specific evolutionary histories and trade-offs were neglected in the investigation of gene-environment interactions. We propose a new “diachronic” approach that considers processes occurred at both evolutionary and lifespan timescales. We focused on a well-characterized population in terms of evolutionary history (i.e. Italians) and we generated genome-wide data for 333 centenarians from the peninsula and 773 geographically-matched healthy individuals. Obtained results showed that: (i) centenarian genomes are enriched for an ancestral component likely shaped by pre-Neolithic migrations; (ii) centenarians born in Northern Italy unexpectedly clustered with controls from Central/Southern Italy suggesting that Neolithic and Bronze Age gene flow did not favor longevity in this population; (iii) local past adaptive events in response to pathogens and targeting arachidonic acid metabolism became favorable for longevity; (iv) lifelong changes in the frequency of several alleles revealed pleiotropy and trade-off mechanisms crucial for longevity. Therefore, we propose that demographic history and ancient/recent population dynamics need to be properly considered to identify genes involved in longevity, which can differ in different temporal/spatial settings.

Nicotinamide and Demographic and Disease transitions: Moderation is Best

Good health and rapid progress depend on an optimal dose of nicotinamide. Too little meat triggers the neurodegenerative condition pellagra and tolerance of symbionts such as tuberculosis (TB), risking dysbioses and impaired resistance to acute infections. Nicotinamide deficiency is an overlooked diagnosis in poor cereal-dependant economies masquerading as 'environmental enteropathy' or physical and cognitive stunting. Too much meat (and supplements) may precipitate immune intolerance and autoimmune and allergic disease, with relative infertility and longevity, via the tryptophan-nicotinamide pathway. This switch favours a dearth of regulatory T (Treg) and an excess of T helper cells. High nicotinamide intake is implicated in cancer and Parkinson's disease. Pro-fertility genes, evolved to counteract high-nicotinamide-induced infertility, may now be risk factors for degenerative disease. Moderation of the dose of nicotinamide could prevent some common diseases and personalised doses at times of stress or, depending on genetic background or age, may treat some other conditions.

Parents of early-maturing girls die younger

According to the life-history theory, rates of sexual maturation have coevolved with mortality rates so that individuals who mature faster tend to die younger. We used two data sets, providing different markers for the speed of pubertal development to test whether rates of sexual maturation of women predict the age at death of their parents. In the data set of Estonian schoolgirls born between 1936 and 1961, the rate of breast development predicted lifespan of both mothers and fathers (irrespectively of their socio-economic position), so that parents of rapidly maturing girls died at younger age. This finding supports the view that fast maturation rates in humans have coevolved with short lifespans and that such trade-offs can be detected as intergenerational phenotypic correlations in modern populations. Menarcheal age of participants of Estonian Biobank (born between 1925 and 1996) did not predict the age of death of their mothers; however, it did predict survival of their fathers, but only in environment where the genetic variation is exposed (families where at least one parent had tertiary education). In such families (where girls also matured 0.2-0.4 years earlier than in poorly educated families), 1-year delay in daughter's menarche corresponded to 9% lower hazard of father's death. Heritability of menarcheal age was also highest in well-educated families. The latter findings are consistent with the idea that genetic differences in the rate of pubertal maturation may be expressed most clearly in well-off families because in such families, the contribution of environmental variance to total phenotypic variance in menarcheal age is smallest. Our findings suggest that with global improvement and equalization of growth conditions, reductions of environmental variation in the rate of maturation increasingly expose the genetic differences in menarcheal age to selection. Under such conditions, selection on menarcheal age has a potential to affect the evolution of lifespan.

Increased risk of incident chronic medical conditions in infertile women: analysis of US claims data

BACKGROUND

The risk of common chronic medical conditions among infertile women is not known.

OBJECTIVE

The objective of the study was to study the association between female infertility and the risk of incident chronic disease.

STUDY DESIGN

This was a retrospective cohort analysis using the Optum deidentified Clinformatics Datamart from 2003 through 2016. A total of 64,345 infertile women were identified by infertility diagnosis, testing, or treatment and compared with 3,128,345 noninfertile patients seeking routine gynecologic care. Women with a prior diagnosis of the relevant chronic disease or cancer or with either diagnosis within 6 months of the index event were excluded. The main outcome was a diagnosis of incident chronic disease as identified by International Classification of Diseases, ninth revision/International Classification of Diseases, 10th revision codes. Results were adjusted for age, index year, nulliparity, race, smoking, obesity, number of visits per year, and highest level of education.

RESULTS

Infertile patients were more likely to develop diabetes (adjusted hazard risk, 1.44, confidence interval, 1.38-1.49), renal disease (adjusted hazard risk, 1.22, confidence interval, 1.12-1.32), liver disease (adjusted hazard risk, 1.25, confidence interval, 1.20-1.30), cerebrovascular disease (adjusted hazard risk, 1.26, confidence interval, 1.15-1.38), ischemic heart disease (adjusted hazard risk, 1.16, confidence interval, 1.09-1.24), other heart disease (adjusted hazard risk, 1.16, confidence interval, 1.12-1.20), and drug abuse (adjusted hazard risk, 1.24, confidence interval, 1.15-1.33) compared with noninfertile patients. Infertile patients were significantly less likely to develop alcohol abuse (adjusted hazard risk, 0.86, confidence interval, 0.79-0.95) compared with noninfertile patients. Risk associations were similar after excluding women with polycystic ovarian syndrome and premature ovarian insufficiency. In subgroup analyses of women who underwent pregnancy and childbirth during enrollment, several previously noted risk associations were attenuated compared with the overall cohort.

CONCLUSION

While the absolute risk of chronic disease is low, infertility is associated with an increased risk of incident chronic disease compared with a group of noninfertile women.

Early-life environment and differences in costs of reproduction in a preindustrial human population

Reproduction is predicted to trade-off with long-term maternal survival, but the survival costs often vary between individuals, cohorts and populations, limiting our understanding of this trade-off, which is central to life-history theory. One potential factor generating variation in reproductive costs is variation in developmental conditions, but the role of early-life environment in modifying the reproduction-survival trade-off has rarely been investigated. We quantified the effect of early-life environment on the trade-off between female reproduction and survival in pre-industrial humans by analysing individual-based life-history data for >80 birth cohorts collected from Finnish church records, and between-year variation in local crop yields, annual spring temperature, and infant mortality as proxies of early-life environment. We predicted that women born during poor environmental conditions would show higher costs of reproduction in terms of survival compared to women born in better conditions. We found profound variation between the studied cohorts in the correlation between reproduction and longevity and in the early-life environment these cohorts were exposed to, but no evidence that differences in early-life environment or access to wealth affected the trade-off between reproduction and survival. Our results therefore do not support the hypothesis that differences in developmental conditions underlie the observed heterogeneity in reproduction-survival trade-off between individuals.

Mid-life fertility: Challenges & policy planning

This review highlights the challenges, priority areas of research and planning, strategies for regulation of services and the need to develop guidelines and laws for fertility treatments during mid-life. The success rate of all treatments is poor in advanced age women because of declining ovarian reserve and natural fertility. There is often a need of third-party involvement which has its own ethical, legal and medical issues. Welfare of children born to older women and early death of parents are important concerns. Most of the new techniques such as the pre-implantation genetic diagnosis, oocyte augmentation, use of stem cells or artificial gametes, ovarian tissue preservation and ovarian transplantation are directed to improve, preserve or replace the declining ovarian reserve. These techniques are costly and have limited availability, safety and efficacy data. Continued research and policies are required to keep pace with these techniques. The other important issues include the patients' personal autonomy and right of self-determination, welfare of offspring, public vs. private funding for research and development of new technologies vs. indiscriminate use of unproven technology. It is important that mid-life fertility is recognized as a distinct area of human reproduction requiring special considerations.

Selection bias in studies of human reproduction-longevity trade-offs

A shorter lifespan as a potential cost of high reproductive effort in humans has intrigued researchers for more than a century. However, the results have been inconclusive so far and despite strong theoretical expectations we do not currently have compelling evidence for the longevity costs of reproduction. Using Monte Carlo simulation, it is shown here that a common practice in human reproduction-longevity studies using historical data (the most relevant data sources for this question), the omission of women who died prior to menopausal age from the analysis, results in severe underestimation of the potential underlying trade-off between reproduction and lifespan. In other words, assuming that such a trade-off is expressed also during reproductive years, the strength of the trade-off between reproduction and lifespan is progressively weakened when women dying during reproductive ages are sequentially and non-randomly excluded from the analysis. In cases of small sample sizes (e.g. few hundreds of observations), this selection bias by reducing statistical power may even partly explain the null results commonly found in this field. Future studies in this field should thus apply statistical approaches that account for or avoid selection bias in order to recover reliable effect size estimates between reproduction and longevity.

SELF-RATED HEALTH AND TEENAGE PREGNANCIES IN ROMA WOMEN: INCREASING HEIGHT IS ASSOCIATED WITH BETTER HEALTH OUTCOMES

This paper reports on the association between early marriage, age at first reproduction and height, as an indicator of childhood environment, and maternal health outcomes among traditional Roma women in Serbia. Demographic data, marital and reproductive histories, height, weight and self-rated health were collected from 414 Roma women living in rural settlements in Serbia in 2015-2017. Data analysis showed that higher age and weight were associated with a greater risk of poor health, greater height contributed to reduced risk of poor health while reproductive variables were insignificant. The study provides evidence that the long-term effects of early childbearing may not always be associated with poorer health status. As indicated by the differences in height, it is likely that women who were capable of reproducing very early on and staying healthy in later life were probably very healthy to begin with. The results probably reflect both the biological and social differences of early childhood. Aside from height, the traditional Roma marriage pattern and social benefits may have an additional protective effect on the health of women.

Telomere length is longer in women with late maternal age

OBJECTIVE

Maternal age at birth of last child has been associated with maternal longevity. The aim of this study was to determine whether older women with a history of late maternal age at last childbirth had a longer leukocyte telomere length than those with maternal age at last childbirth of 29 years or less.

METHODS

A nested case control study was conducted using data from the Long Life Family Study. Three hundred eighty-seven women who gave birth to at least one child and lived to the top fifth percentile of their birth cohort, or died before the top fifth percentile of their birth cohort died, but were at least 70 years old, were studied. Logistic regression models using generalized estimating equations were used to determine the association between tertiles of telomere length and maternal age at last childbirth, adjusting for covariates.

RESULTS

Age at birth of the last child was significantly associated with leukocyte telomere length. Compared with women who gave birth to their last child before the age of 29, women who were past the age of 33 when they had their last child were two to three times more likely to have leukocyte telomere length in the second and third tertiles than in the first tertile.

CONCLUSIONS

These findings show an association between longer leukocyte telomere length and a later maternal age at birth of last child, suggesting that extended maternal age at last childbirth may be a marker for longevity.

Regulation of reproduction and longevity by nutrient-sensing pathways

Nutrients are necessary for life, as they are a crucial requirement for biological processes including reproduction, somatic growth, and tissue maintenance. Therefore, signaling systems involved in detecting and interpreting nutrient or energy levels-most notably, the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway, mechanistic target of rapamycin (mTOR), and adenosine monophosphate-activated protein kinase (AMPK)-play important roles in regulating physiological decisions to reproduce, grow, and age. In this review, we discuss the connections between reproductive senescence and somatic aging and give an overview of the involvement of nutrient-sensing pathways in controlling both reproductive function and lifespan. Although the molecular mechanisms that affect these processes can be influenced by distinct tissue-, temporal-, and pathway-specific signaling events, the progression of reproductive aging and somatic aging is systemically coordinated by integrated nutrient-sensing signaling pathways regulating somatic tissue maintenance in conjunction with reproductive capacity.

Accounting for measurement error in human life history trade-offs using structural equation modeling

OBJECTIVES

Revealing causal effects from correlative data is very challenging and a contemporary problem in human life history research owing to the lack of experimental approach. Problems with causal inference arising from measurement error in independent variables, whether related either to inaccurate measurement technique or validity of measurements, seem not well-known in this field. The aim of this study is to show how structural equation modeling (SEM) with latent variables can be applied to account for measurement error in independent variables when the researcher has recorded several indicators of a hypothesized latent construct.

METHODS

As a simple example of this approach, measurement error in lifetime allocation of resources to reproduction in Finnish preindustrial women is modelled in the context of the survival cost of reproduction. In humans, lifetime energetic resources allocated in reproduction are almost impossible to quantify with precision and, thus, typically used measures of lifetime reproductive effort (e.g., lifetime reproductive success and parity) are likely to be plagued by measurement error. These results are contrasted with those obtained from a traditional regression approach where the single best proxy of lifetime reproductive effort available in the data is used for inference.

RESULTS

As expected, the inability to account for measurement error in women's lifetime reproductive effort resulted in the underestimation of its underlying effect size on post-reproductive survival.

CONCLUSIONS

This article emphasizes the advantages that the SEM framework can provide in handling measurement error via multiple-indicator latent variables in human life history studies.

Reproductive Investment and Health Costs in Roma Women

In this paper, we examine whether variation in reproductive investment affects the health of Roma women using a dataset collected through original anthropological fieldwork among Roma women in Serbia. Data were collected in 2014–2016 in several Roma semi-urban settlements in central Serbia. The sample consisted of 468 Roma women, averaging 44 years of age. We collected demographic data (age, school levels, socioeconomic status), risk behaviors (smoking and alcohol consumption), marital status, and reproductive history variables (the timing of reproduction, the intensity of reproduction, reproductive effort and investment after birth), in addition to self-reported health, height, and weight. Data analyses showed that somatic, short-term costs of reproduction were revealed in this population, while evolutionary, long-term costs were unobservable—contrariwise, Roma women in poor health contributed more to the gene pool of the next generation than their healthy counterparts. Our findings appear to be consistent with simple trade-off models that suggest inverse relationships between reproductive effort and health. Thus, personal sacrifice—poor health as an outcome—seems crucial for greater reproductive success.

Health costs of reproduction are minimal despite high fertility, mortality and subsistence lifestyle

Women exhibit greater morbidity than men despite higher life expectancy. An evolutionary life history framework predicts that energy invested in reproduction trades-off against investments in maintenance and survival. Direct costs of reproduction may therefore contribute to higher morbidity, especially for women given their greater direct energetic contributions to reproduction. We explore multiple indicators of somatic condition among Tsimane forager-horticulturalist women (Total Fertility Rate = 9.1; n =  592 aged 15-44 years, n = 277 aged 45+). We test whether cumulative live births and the pace of reproduction are associated with nutritional status and immune function using longitudinal data spanning 10 years. Higher parity and faster reproductive pace are associated with lower nutritional status (indicated by weight, body mass index, body fat) in a cross-section, but longitudinal analyses show improvements in women's nutritional status with age. Biomarkers of immune function and anemia vary little with parity or pace of reproduction. Our findings demonstrate that even under energy-limited and infectious conditions, women are buffered from the potential depleting effects of rapid reproduction and compound offspring dependency characteristic of human life histories.

Evidence for the Cost of Reproduction in Humans: High Lifetime Reproductive Effort Is Associated with Greater Oxidative Stress in Post-Menopausal Women

Life history theory predicts trade-offs between reproductive effort and maternal survivorship in energy-restricted environments. However, empirical evidence for the positive association between maternal mortality and reproductive effort from energetically challenged human populations are mixed and physiological mechanisms that may underlie this association are poorly understood. We hypothesized that increases in aerobic metabolism during repeated periods of pregnancy and lactation result in increased oxidative stress that may contribute to somatic deterioration, vulnerability to illness, and accelerated aging. We therefore predicted that lifetime gravidity and parity would be related to levels of biomarkers of oxidative stress, as well as antioxidative defence enzymes in post-menopausal women. Our hypothesis was supported by positive linear associations between levels of 8-OHdG, a biomarker of DNA oxidative damage (β = 0.21, p<0.05), levels of antioxidative defence enzyme Cu-Zn SOD (β = 0.25, p<0.05), and number of lifetime pregnancies. Furthermore, independent of age and health status, post-menopausal women with higher gravidity and parity (> = 4 pregnancies per lifetime) had 20% higher levels of 8-OHdG and 60% higher levels of Cu-Zn SOD compared to women with lower gravidity and parity (<4 pregnancies per lifetime). Our results present the first evidence for oxidative stress as a possible cost of reproductive effort in humans.

An Old Mom Keeps You Young: Mother's Age at Last Birth and Offspring Longevity in Nineteenth-Century Utah

This study analyzes the intergenerational effects of late childbearing on offspring's adult longevity in a population in Utah (United States) that does not display evidence of parity-specific birth control-a so-called natural fertility population. Studies have found that for women who experience late menopause and prolonged reproduction, aging is postponed and longevity is increased. This is believed to indicate female "robustness" and the impact of biological or genetic factors. If indeed there is a genetic component involved, one would expect to also find evidence for the intergenerational transmission of longevity benefits. Our study investigates the relationship between prolonged natural fertility of mothers and their offspring's survival rates in adulthood. Gompertz regression models (N = 7,716) revealed that the offspring of mothers who were naturally fertile until a relatively advanced age lived significantly longer. This observed positive effect of late reproduction was not independent of but conditional upon survival of the mother to the end of her fecundity (defined as age 50). Offspring's relative risks at death beyond age 50 were 6-12 percent lower than those of their counterparts born to mothers who had an average age at last birth. Our results, which account for various early, adult, and later-life conditions, as well as shared frailty, suggest that there is a positive relationship between mother's age at last birth and offspring longevity, and strengthen the notion that age at menopause is a good predictor of this relationship.

Fertility History, Children's Gender, and Post-Reproductive Survival in a Longevous Population

The question of whether mothers' fertility history influences their post-reproductive survival has been addressed frequently in the scientific literature. Using data from Villagrande Strisaili, Sardinia, where longevity is higher than anywhere else in Europe, we analyzed the relationship between the fertility pattern of mothers who survived past age 50 (n = 539) and their post-reproductive lifespan. We find that, after adjustment for potential confounders (mothers' birth cohort, survival of spouse), the mothers who on average delivered their children later displayed a reduced mortality risk (‒2.9 percent for each additional year), supporting previously reported findings. We also find that a male-skewed offspring ratio was associated with decreased mortality risk of mothers, with longer survival of mothers who delivered their sons above age 35 (p = 0.005), a result not found for daughters. So far, no biological explanation has been suggested for the positive effect of delivering sons later in life. We conjecture that in our dataset stronger nonbiological factors such as gender-specific sociocultural and economic factors may have masked the negative effect reported in other populations, for which a biological explanation was proposed.

The Trade-Off between Female Fertility and Longevity during the Epidemiological Transition in the Netherlands

Several hypotheses have been put forward to explain the relationship between women's fertility and their post-reproductive longevity. In this study, we focus on the disposable soma theory, which posits that a negative relationship between women's fertility and longevity can be understood as an evolutionary trade-off between reproduction and survival. We examine the relationship between fertility and longevity during the epidemiological transition in the Netherlands. This period of rapid decline in mortality from infectious diseases offers a good opportunity to study the relationship between fertility and longevity, using registry data from 6,359 women born in The Netherlands between 1850 and 1910. We hypothesize that an initially negative relationship between women's fertility and their longevity gradually turns less negative during the epidemiological transition, because of decreasing costs of higher parities. An initially inversed U-shaped association between fertility and longevity changes to zero during the epidemiological transition. This does suggest a diminishing environmental pressure on fertility. However, we find no evidence of an initial linear trade-off between fertility and post-reproductive survival.

Patterns of longevity and fecundity at two temperatures in a set of heat-selected recombinant inbred lines of Drosophila melanogaster

Quantitative trait loci (QTL) were mapped for longevity and fecundity at two temperatures, 20 and 30 °C, in two sets of recombinant inbred lines (RIL) highly differing in thermotolerance. Early fecundity (EF) and longevity showed a negative association between temperatures. For instance, longevity was higher and fecundity was lower in the RIL panel showing higher life span at 30 °C. One X-linked QTL (7B3-12E) co-localized for longevity and EF at 20 °C, with one QTL allele showing a positive additive effect on longevity and a negative effect on EF. The across-RIL genetic correlation between longevity and EF was not significant within each temperature, and most QTL that affect life span have no effect on EF at each temperature. EF and longevity can mostly be genetically uncoupled in the thermotolerance-divergent RIL within each temperature as opposed to between temperatures. QTL were mostly temperature specific, although some trait-specific QTL showed possible antagonistic effects between temperatures.