More Prevalent Prescription of Medicine for Hypertension and Metabolic Syndrome in Males from Couples Undergoing Intracytoplasmic Sperm Injection

Prevalence of impaired renal function among childless men as compared to fathers: a population-based study

Male reproductive impairment has been linked with an increased risk of numerous non-communicable diseases. Yet, epidemiological data on renal disease among subfertile men is scarce. Therefore, by using male childlessness as a proxy for male infertility, we aimed to investigate its association with renal function. Data was sourced from a population-based cohort including 22,444 men. After exclusion of men aged < 45 years (n = 10,842), the remaining men were divided into two groups: these being childless (n = 5494) and fathers (n = 6108). Logistic regression was applied to explore the association between male childlessness and renal impairment. Childless men as compared to fathers, were more likely to have an estimated-glomerular filtration rate < 60 ml/min/1.73m2 (OR 1.36, 95 CI 1.08-1.70; p = 0.008). After adjustment for age, marital status, smoking habits, diabetes, hypertension and other components of metabolic syndrome, childless men were also more likely to have dipstick proteinuria (OR 1.85, 95 CI 1.16-2.95; p = 0.01). With the growing panorama of disease associated with male reproductive impairment, men with fertility issues may constitute a target population with potential benefit from closer follow-up of their renal function.

Causal relationship between genetically predicted type 2 diabetes mellitus and male infertility

Background

Diabetes mellitus (DM) stands as the most prevalent endocrine abnormality affecting the physiological systems and organs and impairing the male reproductive functions. Type 2 Diabetes Mellitus (T2DM), accounting for about 90-95% of DM, is closely associated with male infertility. However, the magnitude of the causal relationships between T2DM and male infertility remains unclear. The current investigation was to explore the causal relationship between T2DM and male infertility utilizing the Mendelian Randomization (MR) analysis.

Methods

A two-sample MR (2SMR) analysis was conducted to investigate the causal relationship between T2DM and male infertility in the European population from the genome-wide association study (GWAS) summary data that was publicly accessible. GWAS for T2DM and male infertility were extracted from the IEU Open GWAS Project database, with the resulting data encompassing 680 cases and 72,799 controls as the outcome data. Five MR methods were employed for the 2SMR analyses, namely the MR-Egger, weighted median estimation (WME), weighted mode (WM), inverse-variance weighted (IVW), and simple mode. The primary analytical technique utilized in this study was the IVW method, and a multivariate MR analysis was executed to examine the potential mediating influences of T2DM on male infertility.

Results

Following were the odds ratios (ORs) and associated 95% CIs derived from IVW (fixed effects), MR-Egger, WM, WME, and simple mode approaches: 0.824 (95% CI 0.703-0.966), 0.726 (95% CI 0.527-1.001), 0.827 (95% CI 0.596-1.150), 0.841 (95% CI 0.654-1.082), and 0.875 (95% CI 0.544-1.405), respectively. The outcomes of the heterogeneity tests were P=0.378 and P=0.384, respectively, implying no heterogeneity. Egger-intercept outcomes were P=0.374, highlighting the absence of pleiotropy. The stability of the results was affirmed through the leave-one-out analysis. Notably, all F-values surpassed 10, indicating the absence of weak bias attributed to instrument variables(IVs).

Conclusions

This research furnishes evidence supporting a causal association between T2DM and male infertility. These insights offer a foundation for future investigations aiming to establish the association between genetically predicted T2DM and male infertility. These outcomes suggest the significance of active monitoring and proactive measures for preventing infertility in male individuals with T2DM. Furthermore, careful consideration is required for individuals of reproductive age to prevent and treat T2DM.

Testosterone deficiency and metabolic disturbances in men who fathered a child by use of donated spermatozoa

Dose–response association between level of impairment of semen quality and risk of morbidity or premature death has been reported. Therefore, it can be presumed that men utilizing donated spermatozoa, i.e. patients with non-obstructive azoospermia, are at highest risk for adverse health outcomes. To evaluate the risks of prescription of medications for common metabolic disturbances and testosterone replacement therapy (TRT) among men who father children with donated spermatozoa—who presumably do it due to severe impairment of fertility. We used Swedish nationwide register data on all fathers who had a live-born child between 2007 and 2014 in order to compare men who fathered children with donated spermatozoa to the ones who became fathers by using own gametes. Cox regression analysis was used in order to estimate the post-conception incidence of prescription of medicines for hypertension (HT), diabetes (type 1 and 2), dyslipidaemia (DLE) or TRT. Starting the follow up at time of conception, models were adjusted for age, educational level, and previous cancer treatment. In total 410,119 childbirths were included in the analysis. Among them, for 390 fathers donated spermatozoa were utilized. Fathers to children conceived with donated spermatozoa had higher risk for having TRT prescribed (HR: 18.14; 95%CI: 11.71–28.10; p ≪ 0.001). Same was true for DLE (HR: 2.08; 95%CI: 1.27–3.39; p = 0.003) but not diabetes. Fathers to children conceived by use of donated spermatozoa are at significantly increased risk for testosterone treatment and dyslipidaemia, necessitating stringent follow up and inclusion in prevention programs.

Association between male infertility and the risk of hypertension: A meta-analysis and literature review

To explore the association between male infertility and hypertension risk, a meta-analysis and systematic review was conducted. Observational studies were sought in Medline, PubMed, EMBASE, Web of Science, and China National Knowledge Infrastructure up to April 30, 2021. Two independent reviewers selected available studies and extracted the data. The association between male infertility and hypertension risk was estimated by calculating the relative risk (RR) and 95% confidence interval (95% CI) using Stata12.0 statistical software. A total of seven studies were included in this meta-analysis, including 102,152 patients and 636,645 healthy individuals. The results demonstrated that male infertility was significantly associated with increased hypertension incidence (RR = 1.08; 95% CI 1.02-1.14; p = 0.004), with moderate-quality evidence. A subgroup analysis based on region showed that a positive association was observed in Europe but not the United States or Asia. This positive association was further confirmed in a cohort study, but not in a case-control study. After adjusting for potential confounders, male infertility was still significantly associated with hypertension risk (RR = 1.06, 95% CI 1.03-1.09). In conclusion, our findings suggest that male infertility increases the risk of hypertension incidence. However, further studies are needed to provide more conclusive evidence.

Type 2 diabetes mellitus and the risk of abnormal spermatozoa: A Mendelian randomization study

Abnormal spermatozoa can not only reduce the fertilization rate, but also prolong the natural conception time and even increase the risk of spontaneous miscarriage. Diabetes mellitus (DM) has become a major global health problem, and its incidence continues to rise, while affecting an increasing number of men in their reproductive years. Type 2 Diabetes Mellitus (T2DM), accounting for about 85-95% of DM, is closely related to the development of sperm. However, the exact association between T2DM and abnormal spermatozoa remains unclear. Herein, we designed a Two-sample Mendelian randomization (MR) study to explore the causal association between T2DM and abnormal spermatozoa risk in European population data which come from the GWAS summary datasets. We selected 9 single nucleotide polymorphisms (SNPs) of T2DM (exposure data) as instrumental variables (IVs), and then retrieved the suitable abnormal spermatozoa genome-wide association study (GWAS) data of European from Ieu Open GWAS Project database which includes 915 cases and 209,006 control as the outcome data. Our results indicate that strict T2DM might not result in a higher risk of abnormal spermatozoa genetically in Europeans (OR: 1.017, 95% confidence interval (CI): 0.771-1.342, p=0.902). Our findings demonstrate that only T2DM may not explain the relatively higher risk of abnormal spermatozoa in men with it in Europeans. In subsequent studies, more comprehensive and larger samples need to be studied to reveal the relationship and potential mechanism between T2DM and abnormal spermatozoa.

Impact of genetic risk score on the association between male childlessness and cardiovascular disease and mortality

Childless men are reported to have a higher risk of cardiovascular disease (CVD) and mortality. Information on inherited genetic risk for CVD has improved the predictive models. Presuming that childlessness is a proxy of infertility we aimed to investigate if childless men inherit more often genetic traits for CVD and if combining genetic and parenthood information improves predictive models for CVD morbidity and mortality. Data was sourced from a large prospective population-based cohort where genetic risk score (GRS) was calculated using two sets of either 27 (GRS 27) or 50 (GRS 50) single nucleotide polymorphisms (SNPs) previously found to be associated with CVD. Part of the participants (n = 2572 men) were randomly assigned to a sub-cohort with focus on CVD which served as an exploratory cohort. The obtained statistically significant results were tested in the remaining (confirmatory) part of the cohort (n = 9548 men). GRS distribution did not differ between childless men and fathers (p-values for interaction between 0.29 and 0.76). However, when using fathers with low GRS as reference high GRS was a strong predictor for CVD mortality, the HR (95% CI) increasing from 1.92 (1.10-3.36) for GRS 50 and 1.54 (0.87-2.75) for GRS 27 in fathers to 3.12 (1.39-7.04) for GRS50 and 3.73 (1.75-7.99) for GRS27 in childless men. The confirmatory analysis showed similar trend. Algorithms including paternal information and GRS were more predictive for CVD mortality at 5 and 10 years follow-ups when compared to algorithms including GRS only (AUC 0.88 (95% CI 0.84-0.92) and 0.86 (95% CI 0.84-0.90), and, AUC 0.81 (95% CI 0.75-0.87) and 0.78 (95% CI 0.73-0.82), respectively). Combining information on parental status and GRS for CVD may improve the predictive power of risk algorithms in middle-aged men. Childless men and those with severe infertility problem may be an important target group for prevention of CVD.

Metabolic Syndrome and Reproduction

Metabolic syndrome (MetS) and infertility are two afflictions with a high prevalence in the general population. MetS is a global health problem increasing worldwide, while infertility affects up to 12% of men. Despite the high prevalence of these conditions, the possible impact of MetS on male fertility has been investigated by a few authors only in the last decade. In addition, underlying mechanism(s) connecting the two conditions have been investigated in few preclinical studies. The aim of this review is to summarize and critically discuss available clinical and preclinical studies on the role of MetS (and its treatment) in male fertility. An extensive Medline search was performed identifying studies in the English language. While several studies support an association between MetS and hypogonadism, contrasting results have been reported on the relationship between MetS and semen parameters/male infertility, and the available studies considered heterogeneous MetS definitions and populations. So far, only two meta-analyses in clinical and preclinical studies, respectively, evaluated this topic, reporting a negative association between MetS and sperm parameters, testosterone and FSH levels, advocating, however, larger prospective investigations. In conclusion, a possible negative impact of MetS on male reproductive potential was reported; however, larger studies are needed.

Sperm biology and male reproductive health

Sperm are unique cells, produced through the complex and precisely orchestrated process of spermatogenesis, in which there are a number of checkpoints in place to guarantee delivery of a high-quality and high-fidelity DNA product. On the other hand, reproductive pressure in males means that to produce more is, in very general terms, to perform better. Balancing quantity and quality in sperm production is thus a delicate process, subject to specific cellular and molecular control mechanisms, and sensitive to environmental conditions, that can impact fertility and offspring health. This Collection is focused on these aspects of sperm biology, as well as their impact on reproductive performance and male infertility.

Male factor infertility and risk of death: a nationwide record-linkage study

STUDY QUESTION

What is the risk of death among men with oligospermia, unspecified male factor and azoospermia in the years following fertility treatment?

SUMMARY ANSWER

No significantly elevated risk was observed among men with oligospermia and unspecified male factor, while an increased risk was found among men with azoospermia.

WHAT IS KNOWN ALREADY

Previous studies have shown associations between male factor infertility and risk of death, but these studies have relied on internal reference groups and the risk of death according to type of male infertility is not well characterized.

STUDY DESIGN, SIZE, DURATION

In this prospective record-linkage cohort study, we identified men who had undergone medically assisted reproduction (MAR) between 1994 and 2015. Data was linked to the Danish causes of death register and sociodemographic registers through personal identification numbers assigned to all Danish citizens at birth.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Men that had undergone MAR in Denmark (MAR Cohort; n = 64 563) were identified from the Danish IVF register, which includes data on whether infertility was due to male factor. For each man in the MAR cohort, five age-matched men who became fathers without fertility treatment were selected from the general population (non-MAR fathers; n = 322 108). Men that could not adequately be tracked in the Danish CPR register (n = 1259) and those that were censored prior to study entry (n = 993) were excluded, leaving a final population of 384 419 men. Risk of death was calculated by Cox regression analysis with age as an underlying timeline and adjustments for educational attainment, civil status and year of study entry. The risk of death was compared among men with and without male factor infertility identified from the IVF register (internal comparisons) as well as to the non-MAR fathers (external comparison).

MAIN RESULTS AND THE ROLE OF CHANCE

The risk of death between the MAR cohort (all men, regardless of infertility) and the non-MAR fathers was comparable [hazard ratio (HR), 1.07; 95% CI, 0.98-1.15]. When the MAR cohort was limited to infertile men, these men were at increased risk of death [HR, 1.27; 95% CI, 1.12-1.44]. However, when stratified by type of male factor infertility, men with azoospermia had the highest risk of death, which persisted when in both the internal [HR, 2.30; 95% CI, 1.54-3.41] and external comparison [HR, 3.32; 95% CI, 2.02-5.40]. No significantly elevated risk of death was observed among men with oligospermia [HR, 1.14; 95% CI, 0.87-1.50] and unspecified male factor [HR, 1.10; 95% CI, 0.75-1.61] compared with the non-MAR fathers. The same trends were observed for the internal comparison.

LIMITATIONS, REASONS FOR CAUTION

Duration of the follow-up was limited and there is limited generalizability to infertile men who do not seek fertility treatment.

WIDER IMPLICATIONS OF THE FINDINGS

Using national health registers, we found an increased risk of death among azoospermic men while no increased risk was found among men with other types of infertility. For the azoospermic men, further insight into causal pathways is needed to identify options for monitoring and prevention.

STUDY FUNDING/COMPETING INTEREST(S)

This study is part of the ReproUnion collaborative study, co-financed by the European Union, Interreg V ÖKS. C.G.'s research stay at Stanford was funded by grants from the University of Copenhagen, Kong Christian den Tiendes Fond, Torben og Alice Frimodt Fond and Julie Von Müllen Fond. M.E. is an advisor for Sandstone and Dadi. All other authors declare no conflict of interests.

TRIAL REGISTRATION NUMBER

Not relevant.

Male childlessness as independent predictor of risk of cardiovascular and all-cause mortality: A population-based cohort study with more than 30 years follow-up

In a recent population-based study, an elevated risk of the Metabolic syndrome (MetS) and type 2 diabetes was found in childless men compared to those who have fathered one or more children. Therefore, by using a larger cohort of more than 22 000 men from the Malmo Preventive Project (MPP) we aimed to expand our observations in order to evaluate the metabolic profile of childless men and to evaluate if childlessness is an additional and independent predictor of major adverse cardiovascular events (MACE), mortality and incident diabetes when accounting for well-known biochemical, anthropometric, socio-economic and lifestyle related known risk factors. Logistic regression was used to assess risk of MACE, diabetes and MetS at baseline. Multivariate Cox regression was used to evaluate the risks of MACE and mortality following the men from baseline screening until first episode of MACE, death from other causes, emigration, or end of follow-up (31^st December 2016) adjusting for age, family history, marital status, smoking, alcohol consumption, educational status, body mass index, prevalent diabetes, high blood lipids, increased fasting glucose and hypertension. Childless men presented with a worse metabolic profile than fathers at the baseline examination, with elevated risk of high triglycerides, odds ratio (OR) 1.24 (95%CI: 1.10–1.42), high fasting glucose OR 1.23 (95%CI: 1.05–1.43) and high blood pressure, OR 1.28 (95%CI: 1.14–1.45), respectively. In the fully adjusted prospective analysis, childless men presented with elevated risk of cardiovascular mortality, HR: 1.33 (95% CI: 1.18–1.49) and all-cause mortality, HR 1.23 (95%CI: 1.14–1.33), respectively. In conclusion, these results add to previous studies showing associations between male reproductive health, morbidity and mortality. Male childlessness, independently of well-known socio-economic, behavioral and metabolic risk factors, predicts risk of cardiovascular disease and mortality. Consequently, this group of men should be considered as target population for preventive measures.

Testosterone replacement therapy in men who conceived with intracytoplasmic sperm injection: nationwide register study

OBJECTIVES

Male hypogonadism is associated with higher risk of co-morbidity and premature mortality. It is, therefore, of utmost importance to identify young men who are at the highest risk of testosterone deficiency and who may benefit from preventive measures. In this context, infertile men constitute a high-risk group. The extent of testosterone replacement therapy (TRT) among infertile men, defined as men who have to undergo assisted reproduction for fatherhood, is currently unknown. Therefore, we evaluated the pattern of prescription of TRT in the years following child conception among men who have fathered children with the help of intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF).

DESIGN

By sourcing data from national population registries, hazard ratio (HR) for subsequent TRT was assessed for IVF and ICSI-treated men and compared to those who conceived spontaneously with age Cox regression analysis adjusted for age, educational level and previous intake of medicines for metabolic diseases.

RESULTS

ICSI and IVF fathers had increased incidence of newly prescribed TRT compared to fathers conceiving spontaneously (ICSI: HR = 3.81, 95% CI = 3.09-4.69, P < 0.001; IVF: HR = 1.54, 95% CI = 1.15-2.05, P = 0.003). After adjustment for prescription of medication for one or more components of the MetS prior to TRT, the risk estimates attenuated but remained robust both for ICSI-treated (HR = 3.17 (95% CI: 2.56-3.9) and IVF-treated men (HR = 1.06 (95% CI: 1.05-1.07).

CONCLUSION

Men who have to utilise powerful techniques, such as ICSI for fathering children, may be at risk for testosterone deficiency. Routine endocrine evaluation of men seeking fertility treatment is hence warranted.

Hypertension and Reproduction

PURPOSE OF REVIEW

Many aspects of reproduction have been associated with increased blood pressure and impaired glucose metabolism that reveals a subsequent increased risk of cardiovascular disease. The aim of this review is to assess reproductive life factors associated with an increased risk of hypertension and cardiovascular disease, e.g., early life programming, sexual, and reproductive health in men and women.

RECENT FINDINGS

Impaired fetal growth, with low birth weight adjusted for gestational age, has been found associated with hypertension in adulthood. Erectile dysfunction, currently considered an early diagnostic marker of cardiovascular disease preceding the manifestation of coronary artery disease by several years, frequently coexisting with hypertension, could also be exacerbated by some antihypertensive drugs. Male hypogonadism or subfertility are associated with increased cardiovascular risk. Hypertensive disorders in pregnancy including preeclampsia represent a major cause of maternal, fetal and neonatal morbidity, and mortality. The risk of developing preeclampsia can be substantially reduced in women at its high or moderate risk with a low dose of acetylsalicylic acid initiated from 12 weeks of gestation. An increased risk of hypertension in women following invasive-assisted reproductive technologies has been newly observed. Blood pressure elevation has been noticed following contraceptive pill use, around the menopause and in postmenopausal age. Furthermore, drug treatment of hypertension has to be considered as a factor with a potential impact on reproduction (e.g., due to teratogenic drug effects). In summary, a deeper understanding of reproductive life effects on hypertension and metabolic abnormalities may improve prediction of future cardiovascular disease.