Extended fertility and longevity: the genetic and epigenetic link

Is it possible that menopause is associated with telomere length? Findings of an integrative review

OBJECTIVE

Knowing the important repercussions of menopause for women's health and that female longevity can be better understood through studies based on aging biomarkers, studies on the relationship between menopause and telomere shortening may help to better understand this stage of life. This study aimed to analyze what research has been produced regarding the relationship between menopause and telomere length.

METHODS

This integrative literature review included searches in PubMed, CINAHL, LILACS, Web of Science and Scopus databases. Four studies were selected for the final sample.

RESULTS

The findings of these studies indicate that older age for menopause and longer reproductive life (difference between age at menopause and menarche) are associated with longer telomeres, that is, with longevity.

CONCLUSION

The relationship between menopause and telomere length is uncertain. The small number of studies included in this review, and the fact that the results indicate that the relationship between menopause and telomere length may be dependent on the stage of the menopause and race/ethnicity, suggest that additional research focusing on these variables should be carried out.

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.

Circular RNA expression profiles of ovarian granulosa cells in advanced-age women explain new mechanisms of ovarian aging

Aim: We aimed to determine the role of granulosa cells (GCs) circular RNA (circRNA) in ovarian aging. Methods: Nine women were recruited, including three diminished ovarian reserve young women, three advanced-aged women and three normal ovarian reserve young women. The circRNA expression profiles of GCs were characterized by CLEAR software. Key circRNA were validated by quantitative reverse transcription PCR. Results: GCs in advanced-age group females exhibited active MHC class II-related biological processes. A total of 3575 circRNAs were found in the advanced age group. Hsa-circ-0031584 appears to be one of the important molecules regulating the mitotic process of GCs. Conclusion: The expression profiles of circRNAs exhibited obvious stage specificity with age which might contribute to ovarian aging progression.

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.

Maternal age at delivery and fertility of the next generation

BACKGROUND

While most known causes of infertility relate to the health of the woman and/or her partner, questions have been raised regarding the possible contributions of transgenerational or epigenetic factors.

OBJECTIVE

The goal of this hypothesis-generating work was to examine whether Generation 1's (G1's) age at the delivery of G2 (Generation 2) was associated with G2's fertility in later life.

METHODS

We conducted a retrospective cohort study of women (G2s) recruited online in 2016. A questionnaire queried G2s regarding demographics and fertility. The primary exposure was G1's age at G2's birth. Outcome measures included the following: 12-month infertility, time to pregnancy, and childlessness. The adjusted relative risk (RR) of G2 infertility and childlessness by G1 age at G2's birth was estimated through a modified Poisson regression approach. The fecundity odds ratio (FOR) for the association between G1's age at G2 birth and time to pregnancy for G2 was estimated by discrete-time survival models, with complementary log-log link.

RESULTS

A total of 2,854 women enrolled. We found no association between G1 age at G2's birth and G2 infertility. Being born to a G1 aged 15-19 years was associated with a longer time to pregnancy for G2 (FOR 0.84, 95% confidence interval 0.72, 0.99), relative to being born to a G1 aged 20-24 years. We observed the suggestion of a possible increased risk of childlessness among G2s born to older G1s, but the estimate was imprecise.

CONCLUSIONS

While being born to a G1 who was 15-19 years old was associated with an increase in G2 time to pregnancy, we found no association between G1 age at G2's birth and infertility and only the suggestion of a modest association with childlessness. These data suggest a possible subtle effect of G1 age at G2's birth on G2 fertility, which warrants further study.

Essential role of autophagy in resource allocation during sexual reproduction

Sexual reproduction is the most common form of reproduction among eukaryotes, which is characterized by a series of massive cellular or tissue renovations. Recent studies have revealed novel functions of autophagy during sexual reproductive processes, ranging from yeast to mammals. In mammals, autophagy is indispensable for spermatogenesis and oogenesis, and it participates in early embryonic development and maternal-fetus crosstalk to ensure the development of embryos or fetuses. Thus, autophagy provides the molecular basis for resource allocation among parents and their offspring, providing an important way to benefit the next generation.Abbreviations: ATG: autophagy-related; Becn1: beclin 1, autophagy related; CMA: chaperone-mediated autophagy; epg: ectopic PGL granules; ES: ectoplasmic specialization; EVTs: extravillous trophoblasts; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PCD: programmed cell death; PTB: preterm birth; STB: syncytiotrophoblast.

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.

Molecular mechanisms of embryonic implantation in mammals: Lessons from the gene manipulation of mice

BACKGROUND

Human infertility has become a serious and social issue all over the world, especially in developed countries. Numerous types of assisted reproductive technology have been developed and are widely used to treat infertility. However, pregnancy outcomes require further improvement. It is essential to understand the cross-talk between the uterus (mother) and the embryo (fetus) in pregnancy, which is a very complicated event.

METHODS

The mammalian uterus requires many physiological and morphological changes for pregnancy-associated events, including implantation, decidualization, placentation, and parturition, to occur. Here is discussed recent advances in the knowledge of the molecular mechanisms underlying these reproductive events - in particular, embryonic implantation and decidualization - based on original and review articles.

MAIN FINDINGS RESULTS

In mice, embryonic implantation and decidualization are regulated by two steroid hormones: estrogen and progesterone. Along with these hormones, cytokines, cell-cycle regulators, growth factors, and transcription factors have essential roles in implantation and decidualization in mice.

CONCLUSION

Recent studies using the gene manipulation of mice have given considerable insight into the molecular mechanisms underlying embryonic implantation and decidualization. However, as most of the findings are based on mice, comparative research using different mammalian species will be useful for a better understanding of the species-dependent differences that are associated with reproductive events, including embryonic implantation.

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.

Genetic variants determining survival and fertility in an adverse African environment: a population-based large-scale candidate gene association study

Human survival probability and fertility decline strongly with age. These life history traits have been shaped by evolution. However, research has failed to uncover a consistent genetic determination of variation in survival and fertility. As an explanation, such genetic determinants have been selected in adverse environments, in which humans have lived during most of their history, but are almost exclusively studied in populations in modern affluent environments. Here, we present a large-scale candidate gene association study in a rural African population living in an adverse environment. In 4387 individuals, we studied 4052 SNPs in 148 genes that have previously been identified as possible determinants of survival or fertility in animals or humans. We studied their associations with survival comparing newborns, middle-age adults, and old individuals. In women, we assessed their associations with reported and observed numbers of children. We found no statistically significant associations of these SNPs with survival between the three age groups nor with women's reported and observed fertility. Population stratification was unlikely to explain these results. Apart from a lack of power, we hypothesise that genetic heterogeneity of complex phenotypes and gene-environment interactions prevent the identification of genetic variants explaining variation in survival and fertility in humans.

Circular RNA expression profiling of human granulosa cells during maternal aging reveals novel transcripts associated with assisted reproductive technology outcomes

Circular RNAs (circRNAs) are a unique class of endogenous RNAs which could be used as potential diagnostic and prognostic biomarkers of many diseases. Our study aimed to investigate circRNA profiles in human granulosa cells (GCs) during maternal aging and to uncover age-related circRNA variations that potentially reflect decreased oocyte competence. CircRNAs in GCs from in vitro fertilization (IVF) patients with young age (YA, ≤ 30 years) and advanced age (AA, ≥ 38 years) were profiled by microarray, and validated in 20 paired samples. The correlation between circRNAs expression and clinical characteristics was analyzed in additional 80 samples. Chip-based analysis revealed 46 up-regulated and 11 down-regulated circRNAs in AA samples (fold change > 2.0). Specifically, circRNA_103829, circRNA_103827 and circRNA_104816 were validated to be up-regulated, while circRNA_101889 was down-regulated in AA samples. After adjustment for gonadotropin treatment, only circRNA_103827 and circRNA_104816 levels were positively associated with maternal age (partial r = 0.332, P = 0.045; partial r = 0.473, P = 0.003; respectively). Moreover, circRNA_103827 and circRNA_104816 expressions in GCs were negatively correlated with the number of top quality embryos (r = -0.235, P = 0.036; r = -0.221, P = 0.049; respectively). Receiver operating characteristic (ROC) curve analysis indicated that the performance of circRNA_103827 for live birth prediction reached 0.698 [0.570–0.825], with 77.2% sensitivity and 60.9% specificity (P = 0.006), and that of circRNA_104816 was 0.645 [0.507–0.783] (P = 0.043). Bioinformatics analysis revealed that both circRNAs were potentially involved in glucose metabolism, mitotic cell cycle, and ovarian steroidogenesis. Therefore, age-related up-regulation of circRNA_103827 and circRNA_104816 might be potential indicators of compromised follicular micro-environment which could be used to predict IVF prognosis, and improve female infertility management.

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.