Associations between epigenetic age acceleration and infertility

Epigenetic aging and fecundability: the Norwegian Mother, Father and Child Cohort Study

STUDY QUESTION

Is there an association between male or female epigenetic age acceleration (EAA) or deceleration (EAD) and fecundability?

SUMMARY ANSWER

We do not find compelling evidence of an association between EAA or EAD and fecundability.

WHAT IS KNOWN ALREADY

Prior research has shown that female accelerated epigenetic aging is associated with unfavorable clinical fecundity outcomes and use of in vitro fertilization, and that epigenetic aging in sperm cells is associated with unfavorable sperm parameters. Studies of epigenetic aging and fecundability among individuals who conceive naturally are lacking.

STUDY DESIGN, SIZE, DURATION

This study is based on the Norwegian Mother, Father and Child Cohort Study (MoBa), a population-based pregnancy cohort which recruited pregnant couples between 1999 and 2008. We used data from 1657 couples (women and men) with planned naturally conceived pregnancies and available blood samples.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Methylation levels were measured in DNA from blood samples taken recruitment (at ∼18 gestational weeks) from pregnant women and their partners using the Illumina Methylation EPIC Array. To obtain a measure of EAA/EAD, we performed a linear regression of each of seven different established epigenetic biomarkers (DNAmAge by Horvath, DNAmAge by Hannum et al., PhenoAge by Levine et al., DunedinPoAm by Belsky et al., DunedinPACE by Belsky et al., DNAmTL by Lu et al., and GrimAge by Lu et al.) against chronological age. We fitted proportional probability regression models to obtain fecundability ratios (FRs) for each standard deviation increase in epigenetic aging, and obtained crude and adjusted (for body mass index, smoking, and education level) estimates. Results were evaluated at a false discovery rate (FDR) of 5%. We evaluated all models for non-linear associations using categories of epigenetic age where appropriate.

MAIN RESULTS AND THE ROLE OF CHANCE

Although the DunedinPACE clock in males demonstrated slightly increasing fecundability with increasing EAA (adjusted FR 1.05 per one standard deviation increase in EAA, 95% CI 1.00-1.10), this was not robust when evaluated at an FDR of 5%. We found evidence of non-linearity between biological aging and fecundability in two models in females and three models in males, but non-linear associations were weak and conflicting.

LIMITATIONS, REASONS FOR CAUTION

As MoBa is a pregnancy cohort, our findings may not be generalizable to all couples attempting conception. Fecundability is a couple-level measure, and any impacts of epigenetic aging in each partner may be obscured by effects of the other partner.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings contrast with those of prior studies, which have indicated an association between EAA and unfavorable clinical fertility outcomes in populations using fertility treatments, possibly due to less important effects of epigenetic aging among couples who conceive naturally. More research is needed on the association between blood-based EAA and clinical fertility parameters in both sexes.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the Research Council of Norway through its Medical Student Research Program funding scheme (project number 271555/F20), its Centres of Excellence funding scheme (project number 262700), and a grant from the Women's Health Program (320656). Co-funding was also received from the Strategic Research Council (SRC), FLUX consortium, decision numbers 345130 and 345131; the National Institute on Aging (R01AG075208); grants to the Max Planck-University of Helsinki Center from the Max Planck Society (decision number 5714240218), Jane and Aatos Erkko Foundation, Faculty of Social Sciences at the University of Helsinki, and Cities of Helsinki, Vantaa, and Espoo; and the European Research Council; and the European Research Council (ERC Synergy, BIOSFER, grant number 101071773, and the Horizon 2020 research and innovation program, grant number 947684). The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Parental epigenetic age acceleration and risk of adverse birth outcomes: the Norwegian mother, father and child cohort study

BACKGROUND

Few studies have examined associations between maternal epigenetic age acceleration and adverse birth outcomes, and none have investigated paternal epigenetic age acceleration. Our objective was to assess the associations of parental (both maternal and paternal) epigenetic age acceleration in relation to birth outcomes.

METHODS

Parental epigenetic age was estimated using seven established epigenetic clocks in 2198 mothers and 2193 fathers from the Norwegian Mother, Father, and Child Cohort Study (MoBa). Individual epigenetic age acceleration was then calculated as residuals from linear regressions of estimates from the epigenetic clocks on chronological age. Further, linear regression was used to analyze differences in continuous outcomes (gestational length and standardized birthweight), while logistic regression was used for binary outcomes (preterm birth, post-term birth, small-for-gestational age [SGA], large-for-gestational age [LGA], and pre-eclampsia), adjusting for chronological age, parity, educational level, smoking, and BMI.

RESULTS

Increasing maternal, but not paternal, epigenetic age acceleration was associated with decreased gestational length for five out of six clocks, with adjusted estimates ranging from a mean 0.51-day decrease (95% CI - 1.00, - 0.02; p-value 0.043) for the Horvath clock to a 0.80-day decrease (95% CI - 1.29, - 0.31; p-value 0.002) for the Levine clock. An association with increasing maternal epigenetic age acceleration according to the DunedinPACE clock was also seen with greater standardized birthweight [mean difference 0.08 (95% CI 0.04, 0.12; p-value < 0.001]. These results were also reflected in an increased risk of spontaneous preterm birth and LGA. No associations were observed with post-term birth, SGA, or pre-eclampsia.

CONCLUSIONS

Maternal, but not paternal, epigenetic age acceleration is associated with shorter pregnancies and an increased risk of spontaneous preterm birth. This may suggest that women's biological age acceleration, including factors such as metabolic and physiologic state, is an additional risk factor for preterm delivery, beyond chronological age.

Mitochondria: the epigenetic regulators of ovarian aging and longevity

Ovarian aging is a major health concern for women. Ovarian aging is associated with reduced health span and longevity. Mitochondrial dysfunction is one of the hallmarks of ovarian aging. In addition to providing oocytes with optimal energy, the mitochondria provide a co-substrate that drives epigenetic processes. Studies show epigenetic alterations, both nuclear and mitochondrial contribute to ovarian aging. Both, nuclear and mitochondrial genomes cross-talk with each other, resulting in two ways orchestrated anterograde and retrograde response that involves epigenetic changes in nuclear and mitochondrial compartments. Epigenetic alterations causing changes in metabolism impact ovarian function. Key mitochondrial co-substrate includes acetyl CoA, NAD+, ATP, and α-KG. Thus, enhancing mitochondrial function in aging ovaries may preserve ovarian function and can lead to ovarian longevity and reproductive and better health outcomes in women. This article describes the role of mitochondria-led epigenetics involved in ovarian aging and discusses strategies to restore epigenetic reprogramming in oocytes by preserving, protecting, or promoting mitochondrial function.

Causal association of epigenetic age acceleration and risk of subacute thyroiditis: a bidirectional Mendelian randomization study

BACKGROUND

Epigenetic age accelerations (EAAs) are a promising new avenue of research, yet their investigation in subacute thyroiditis (SAT) remains scarce. Our study endeavors to fill this void by exploring the potential causal association between EAAs and SAT.

METHODS

Our study utilized publicly available genome-wide association study (GWAS) data of European ancestry to conduct a bidirectional Mendelian randomization (MR) study. Five MR methods were employed to measure causal association between EAAs and SAT multiple analyses were utilized to perform quality control.

RESULTS

Our study evaluated causal association between SAT and four EAAs, included GrimAge acceleration (GrimAA), Hannum age acceleration (HannumAA), PhenoAge acceleration (PhenoAA), intrinsic epigenetic age acceleration (IEAA). Results showed that there is a significant causal association between PhenoAA and SAT (OR 1.109, 95% CI 1.000-1.228, p = 0.049, by IVW method). On the contrary, SAT was associated with IEAA (OR 0.933, 95% CI 0.884-0.984, p = 0.011, by IVW method; OR 0.938, 95% CI 0.881-0.998, p = 0.043, by weighted median method). Leave-one-out sensitivity analysis, heterogeneity test, pleiotropy test, and MR-PRESSO analysis provide good quality control.

CONCLUSION

The bidirectional MR analysis concluded that an increase in PhenoAA was correlated with a higher risk of SAT, indicating a potential causal relationship between PhenoAA and risk of SAT. Conversely, SAT was found to be closely associated with IEAA, suggesting that SAT may accelerate the aging process. Slowing down biological aging has emerged as a new research direction in curbing SAT.

Psychoemotional and Financial Impact on Infertile Women in a Romanian Population

OBJECTIVES

The diagnosis of infertility affects between 8-12% of couples of childbearing age worldwide. It is difficult to manage infertility, which often generates anxiety and depression.

MATERIAL AND METHODS

We conducted a study that included women of childbearing age who were unsuccessful in getting pregnant. Our research was based on a questionnaire distributed online via social media and it was carried out over a period of two months. The questionnaire comprised 35 questions and intended to highlight the psychological impact of infertility diagnosis on the female participants in the present study.

RESULTS

A total of 486 women with a diagnosis of infertility responded to the online questionnaire. Subjects had an average age between 31 and 40 years (58.4%) and most of them (80.2%) came from urban areas. It was found that 38.1% of patients experienced a very high level of stress generated by their infertility diagnosis and 54.7% stated that their greatest fear was that they would never get pregnant; 41.4% of these patients claimed that their quality of life was affected and 31.7% indicated a negative impact even on their couple life. Of all participants to the questionnaire, 96.6% stated that the costs of treatments or even assisted reproduction procedures were an additional stress and 73.7% believed that religion played an important moral role.

CONCLUSIONS

The women who were enrolled in the current study recognized the negative impact of their infertility diagnosis on both themselves and their couple's lives. At the same time, they believed in Divine help and looked optimistically to the future in terms of achieving pregnancy.

Epigenetic age acceleration in follicular fluid and markers of ovarian response among women undergoing IVF

STUDY QUESTION

Are markers of epigenetic age acceleration in follicular fluid associated with outcomes of ovarian stimulation?

SUMMARY ANSWER

Increased epigenetic age acceleration of follicular fluid using the Horvath clock, but not other epigenetic clocks (GrimAge and Granulosa Cell), was associated with lower peak estradiol levels and decreased number of total and mature oocytes.

WHAT IS KNOWN ALREADY

In granulosa cells, there are inconsistent findings between epigenetic age acceleration and ovarian response outcomes.

STUDY DESIGN, SIZE, DURATION

Our study included 61 women undergoing IVF at an academic fertility clinic in the New England area who were part of the Environment and Reproductive Health Study (2006-2016).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants provided a follicular fluid sample during oocyte retrieval. DNA methylation of follicular fluid was assessed using a genome-wide methylation screening tool. Three established epigenetic clocks (Horvath, GrimAge, and Granulosa Cell) were used to predict DNA-methylation-based epigenetic age. To calculate the age acceleration, we regressed epigenetic age on chronological age and extracted the residuals. The association between epigenetic age acceleration and ovarian response outcomes (peak estradiol levels, follicle stimulation hormone, number of total, and mature oocytes) was assessed using linear and Poisson regression adjusted for chronological age, three surrogate variables (to account for cellular heterogeneity), race, smoking status, initial infertility diagnosis, and stimulation protocol.

MAIN RESULTS AND ROLE OF CHANCE

Compared to the median chronological age of our participants (34 years), the Horvath clock predicted, on an average, a younger epigenetic age (median: 24.2 years) while the GrimAge (median: 38.6 years) and Granulosa Cell (median: 39.0 years) clocks predicted, on an average, an older epigenetic age. Age acceleration based on the Horvath clock was associated with lower peak estradiol levels (-819.4 unit decrease in peak estradiol levels per standard deviation increase; 95% CI: -1265.7, -373.1) and fewer total (% change in total oocytes retrieved per standard deviation increase: -21.8%; 95% CI: -37.1%, -2.8%) and mature oocytes retrieved (% change in mature oocytes retrieved per standard deviation increase: -23.8%; 95% CI: -39.9%, -3.4%). The age acceleration based on the two other epigenetic clocks was not associated with markers of ovarian response.

LIMITATIONS, REASONS FOR CAUTION

Our sample size was small and we did not specifically isolate granulosa cells from follicular fluid samples so our samples could have included mixed cell types.

WIDER IMPLICATIONS OF THE FINDINGS

Our results highlight that certain epigenetic clocks may be predictive of ovarian stimulation outcomes when applied to follicular fluid; however, the inconsistent findings for specific clocks across studies indicate a need for further research to better understand the clinical utility of epigenetic clocks to improve IVF treatment.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by grants ES009718, ES022955, ES000002, and ES026648 from the National Institute of Environmental Health Sciences (NIEHS) and a pilot grant from the NIEHS-funded HERCULES Center at Emory University (P30 ES019776). RBH was supported by the Emory University NIH Training Grant (T32-ES012870).

TRIAL REGISTRATION NUMBER

N/A.

Monogram and Heat Map on Magnetic Resonance Imaging to Evaluate the Recommendation for Myomectomy in Patients with Infertility: A Pilot Study

Uterine myomas can cause infertility. Studies are attempting to determine the indications for myomectomy. However, the multiplicity and localization of myomas complicate this issue. We aimed to develop a visualization tool to aid patients with infertility in their decision-making for myomectomy. We included 191 women with uterine myoma attending an outpatient infertility clinic, of whom 124 patients underwent myomectomy. Of these, 65 (52.4%) patients became pregnant within 17.6 months after surgery, and 54 (83.1%) of them had a live birth. A logistic regression model predicting the pregnancy rate (area under the curve, 0.82; 95% confidence interval, 0.74-0.89; validation value, 74.6%) was generated using the leave-one-out cross-validation method. This model incorporated five factors: age, maximum level of infertility intervention following myomectomy, presence of submucosal myoma, maximum diameter of the myoma, and type of myomas (multiple or single). We successfully visualized the degree of involvement of each factor in the pregnancy rate by developing a nomogram based on this model. We expanded the data from the preoperative magnetic resonance images and applied machine learning using a convolutional neural network. The classification accuracy was 71.4% for sensitivity and 77.7% for specificity. Heatmap images, generated using gradient-weighted class activation mapping to show the classification results of this model, could distinguish between myomas that required enucleation and those that did not. Although a larger sample size is needed to further validate our findings, this innovative pilot study demonstrates the potential of machine learning to refine assessment criteria and improve patient decision-making.

The risk of perinatal and cardiometabolic complications in pregnancies conceived by medically assisted reproduction

PURPOSE

To examine the impact of medically assisted fertility treatments on the risk of developing perinatal and cardiometabolic complications during pregnancy and in-hospital deliveries.

METHODS

We conducted a retrospective cohort study using medical health records of deliveries occurring in 2016-2022 at a women's specialty hospital in a southern state of the Unites States (US). Pregnancies achieved using medically assisted reproductive (MAR) techniques were compared with unassisted pregnancies using propensity score matching (PSM), based on demographic, preexisting health, and reproductive factors. Study outcomes included cesarean delivery, gestational diabetes mellitus (GDM), hypertensive disorders of pregnancy (HDP), delivery complications, and postpartum readmission. We used Poisson regression with robust standard errors to generate risk ratios (RRs) and 95% confidence intervals (CIs) for all study outcomes.

RESULTS

Among 57,354 deliveries, 586 (1.02%) pregnancies were achieved using MAR and 56,768 (98.98%) were unassisted ("non-MAR"). Compared to the non-MAR group, MAR pregnancies had significantly higher prevalence of all study outcomes, including GDM (15.9% vs. 11.2%, p < 0.001), HDP (28.2% vs. 21.1%, p < 0.001), cesarean delivery (56.1% vs. 34.6%, p < 0.001), delivery complications (10.9% vs. 6.8%, p = 0.03), and postpartum readmission (4.3% vs. 2.7%, p = 0.02). In a PSM sample of 584 MAR and 1,727 unassisted pregnancies, MAR was associated with an increased risk of cesarean delivery (RR = 1.11, 95% CI = 1.01-1.22); whereas IVF was associated with an increased risk of cesarean delivery (RR = 1.15, 95% CI = 1.03-1.28) and delivery complications (RR = 1.44, 95% CI = 1.04-2.01).

CONCLUSIONS

Women who conceived with MAR were at increased risk of cesarean deliveries, and those who conceived with IVF were additionally at risk of delivery complications.

Age-related decline in spermatogenic activity accompanied with endothelial cell senescence in male mice

Male fertility decreases with aging, with spermatogenic decline being one of its causes. Altered testis environment is suggested as a cause of the phenotype; however, the associated mechanisms remain unclear. Herein, we investigated the age-related changes in testicular somatic cells on spermatogenic activity. The number and proliferation of spermatogonia significantly reduced with aging in mice. Interestingly, senescence-associated β-galactosidase-positive cells appeared in testicular endothelial cell (EC) populations, but not in germ cell populations, with aging. Transcriptome analysis of ECs indicated that senescence occurred in the ECs of aged mice. Furthermore, the support capacity of ECs for spermatogonial proliferation significantly decreased with aging; however, the senolytic-induced removal of senescent cells from aged ECs restored their supporting capacity to a comparable level as that of young ECs. Our results suggest that the accumulation of senescent ECs in the testis is a potential factor contributing to the age-related decline in spermatogenic activity.

A DNA Methylation Perspective on Infertility

Infertility affects a significant number of couples worldwide and its incidence is increasing. While assisted reproductive technologies (ART) have revolutionized the treatment landscape of infertility, a significant number of couples present with an idiopathic cause for their infertility, hindering effective management. Profiling the genome and transcriptome of infertile men and women has revealed abnormal gene expression. Epigenetic modifications, which comprise dynamic processes that can transduce environmental signals into gene expression changes, may explain these findings. Indeed, aberrant DNA methylation has been widely characterized as a cause of abnormal sperm and oocyte gene expression with potentially deleterious consequences on fertilization and pregnancy outcomes. This review aims to provide a concise overview of male and female infertility through the lens of DNA methylation alterations.

Facilitation of Ovarian Response by Mechanical Force-Latest Insight on Fertility Improvement in Women with Poor Ovarian Response or Primary Ovarian Insufficiency

The decline in fertility in aging women, especially those with poor ovarian response (POR) or primary ovarian insufficiency (POI), is a major concern for modern IVF centers. Fertility treatments have traditionally relied on gonadotropin- and steroid-hormone-based IVF practices, but these methods have limitations, especially for women with aging ovaries. Researchers have been motivated to explore alternative approaches. Ovarian aging is a complicated process, and the deterioration of oocytes, follicular cells, the extracellular matrix (ECM), and the stromal compartment can all contribute to declining fertility. Adjunct interventions that involve the use of hormones, steroids, and cofactors and gamete engineering are two major research areas aimed to improve fertility in aging women. Additionally, mechanical procedures including the In Vitro Activation (IVA) procedure, which combines pharmacological activators and fragmentation of ovarian strips, and the Whole Ovary Laparoscopic Incision (WOLI) procedure that solely relies on mechanical manipulation in vivo have shown promising results in improving follicle growth and fertility in women with POR and POI. Advances in the use of mechanical procedures have brought exciting opportunities to improve fertility outcomes in aging women with POR or POI. While the lack of a comprehensive understanding of the molecular mechanisms that lead to fertility decline in aging women remains a major challenge for further improvement of mechanical-manipulation-based approaches, recent progress has provided a better view of how these procedures promote folliculogenesis in the fibrotic and avascular aging ovaries. In this review, we first provide a brief overview of the potential mechanisms that contribute to ovarian aging in POI and POR patients, followed by a discussion of measures that aim to improve ovarian folliculogenesis in aging women. At last, we discuss the likely mechanisms that contribute to the outcomes of IVA and WOLI procedures and potential future directions.

Maternal Risk of Cardiovascular Disease After Use of Assisted Reproductive Technologies

Importance

The use of assisted reproductive technologies (ARTs) is steadily increasing worldwide. The outcomes associated with treatment for an individual's long-term health, including risk of cardiovascular disease (CVD), remain largely unknown, due to the small number of studies and their limited follow-up time.

Objective

To study whether the risk of CVD is increased among individuals who have given birth after ART compared with those who have given birth without ART.

Design, Setting, and Participants

A registry-based cohort study was conducted using nationwide data from Denmark (1994-2014), Finland (1990-2014), Norway (1984-2015), and Sweden (1985-2015). Data analysis was conducted from January to August 2022. A total of 2 496 441 individuals with a registered delivery in the national birth registries during the study period were included, and 97 474 (4%) of these gave birth after ART.

Exposures

Data on ART conception were available from ART quality registries and/or medical birth registries.

Main Outcomes and Measures

Information on CVD was available from patient and cause of death registries. The risk of CVD was estimated with Cox proportional hazards regression, adjusting for age, calendar year of start of follow-up, parity, diagnosis of polycystic ovary syndrome, diabetes, chronic hypertension, and country.

Results

Median follow-up was 11 (IQR, 5-18) years. The mean (SD) age of women with no use of ART was 29.1 (4.9) years, and the age of those who used ART was 33.8 (4.7) years. The rate of any CVD was 153 per 100 000 person-years. Individuals who gave birth after using ART had no increased risk of CVD (adjusted hazard ratio [AHR], 0.97; 95% CI, 0.91-1.02), with evidence of heterogeneity between the countries (I2 = 76%; P = .01 for heterogeneity). No significant differences in the risk of ischemic heart disease, cerebrovascular disease, stroke, cardiomyopathy, heart failure, pulmonary embolism, or deep vein thrombosis were noted with use of ART. However, there was a tendency for a modest reduction in the risk of myocardial infarction (AHR, 0.80; 95% CI, 0.65-0.99), with no notable heterogeneity between countries.

Conclusions and Relevance

The findings of this study suggest that women who gave birth after ART were not at increased risk of CVD over a median follow-up of 11 years compared with those who conceived without ART. Longer-term studies are needed to further examine whether ART is associated with higher risk of CVD.

Epigenetic clocks and female fertility timeline: A new approach to an old issue?

Worldwide increase in life expectancy has boosted research on aging. Overcoming the concept of chronological age, higher attention has been addressed to biological age, which reflects a person's real health state, and which may be the resulting combination of both intrinsic and environmental factors. As epigenetics may exert a pivotal role in the biological aging, epigenetic clocks were developed. They are based on mathematical models aimed at identifying DNA methylation patterns that can define the biological age and that can be adopted for different clinical scopes (i.e., estimation of the risks of developing age-related disorders or predicting lifespan). Recently, epigenetic clocks have gained a peculiar attention in the fertility research field, in particular in the female counterpart. The insight into the possible relations between epigenetic aging and women's infertility might glean additional information about certain conditions that are still not completely understood. Moreover, they could disclose significant implications for health promotion programs in infertile women. Of relevance here is that the impact of biological age and epigenetics may not be limited to fertility status but could translate into pregnancy issues. Indeed, epigenetic alterations of the mother may transfer into the offspring, and pregnancy itself as well as related complications could contribute to epigenetic modifications in both the mother and newborn. However, even if the growing interest has culminated in the conspicuous production of studies on these topics, a global overview and the availability of validated instruments for diagnosis is still missing. The present narrative review aims to explore the possible bonds between epigenetic aging and fertility timeline. In the "infertility" section, we will discuss the advances on epigenetic clocks focusing on the different tissues examined (endometrium, peripheral blood, ovaries). In the "pregnancy" section, we will discuss the results obtained from placenta, umbilical cord and peripheral blood. The possible role of epigenetic aging on infertility mechanisms and pregnancy outcomes represents a question that may configure epigenetic clock as a bond between two apparently opposite worlds: infertility and pregnancy.