Male partners of subfertile couples in which the spouse is obese display adverse weight and lifestyle associated with reduced sperm quality

The impact of obesity and metabolic health on male fertility: a systematic review

The impact of paternal obesity and metabolic disease on semen quality and fertility outcomes is not fully appreciated. With increasing obesity rates, researchers have studied the intricate relationship between paternal body mass index, metabolic health, and male fertility. This systematic review identified 112 articles in the MEDLINE database between 2013 and 2023 that investigated the effects of body mass index, diabetes, metabolic syndrome, exercise, weight loss medication, or bariatric surgery on semen parameters, sperm quality, or fertility outcomes. This review suggests that obesity, diabetes, and metabolic syndrome have a negative impact on various parameters of male fertility, from semen quality to sperm deoxyribonucleic acid integrity. There is also mounting evidence that male obesity is correlated negatively with live births via both natural conception and assisted reproductive technologies. Lifestyle interventions, such as physical exercise, generally appear to improve male fertility markers; however, the type and intensity of exercise may play a crucial role. Pharmacologic treatments for weight loss, such as metformin and glucagon-like peptide 1 agonists, present a more complex picture, with studies suggesting both beneficial and detrimental effects on male reproductive health. Similarly, surgical interventions, such as gastric bypass surgery, show promise in improving hormonal imbalances but have mixed effects on semen parameters. Future research is needed to clarify these associations and inform clinical guidelines. In the interim, health practitioners should incorporate these insights into clinical practices, encouraging proactive lifestyle changes and providing targeted treatments to improve male reproductive health.

Sperm DNA damage: The possible link between obesity and male infertility, an update of the current literature

Obesity prevalence worldwide is increasing significantly. Whilst maternal obesity has clear detrimental impacts on fertility, pregnancy and foetal outcomes, more recently there has been an increasing focus on the role of paternal obesity in human fertility. Recent meta-analyses have indicated that obesity in men negatively affects basic sperm parameters such as sperm count, concentration and motility, increases the incidence of infertility and reduces the chances of conception. Sperm DNA damage, typically characterised by DNA strand breaks and oxidation of DNA nucleotides, is a specialised marker of sperm quality that has been independently associated with recurrent miscarriage, reduced assisted reproduction success and increased mutational loads in subsequent offspring. Whilst, there are still conflicting data in humans as to the association of obesity in men with sperm DNA damage, evidence from rodent models is clear, indicating that male obesity increases sperm DNA damage. Human data are often conflicting because of the large heterogeneity amongst studies, the use of body mass index as the indicator of obesity and the methods used for detection of sperm DNA damage. Furthermore, comorbidities of obesity (i.e., heat stress, adipokines, insulin resistance, changes in lipids, hypogonadism and obstructive sleep apnoea) are also independently associated with increased sperm DNA damage that is not always modified in men with obesity, and as such may provide a causative link to the discrepancies amongst human studies. In this review, we provide an update on the literature regarding the associations between obesity in men and fertility, basic sperm parameters and sperm DNA damage. We further discuss potential reasons for the discrepancies in the literature and outline possible direct and indirect mechanisms of increased sperm DNA damage resulting from obesity. Finally, we summarise intergenerational obesity through the paternal linage and how sperm DNA damage may contribute to the transmission.

BMI and miscarriage after IVF

PURPOSE OF REVIEW

To summarize recent findings related to the risk of miscarriage in women with elevated BMI undergoing IVF, and the mechanisms involved in said risk.

RECENT FINDINGS

Miscarriage rates are increased in overweight and obese women in both natural and assisted reproduction. Oocyte and embryo quality assessed according to classic morphological static parameters does not seem to be affected by excessive female body weight. Despite the initial lack of consensus between studies regarding embryo morphokinetics in obese women, blastocyst formation and quality have recently been shown to be similar across BMI groups, even in the case of euploid embryos. However, some metabolomic differences have been described in oocytes and embryos from obese women, thus pointing to a functional alteration. In women with elevated BMI, the percentage of aneuploid embryos is similar to that of normal weight women, and rates of miscarriage are higher, despite the transfer of euploid embryos. Therefore, the origin of the increased pregnancy loss rate after IVF in these women may be related to metabolomic, epigenetic or mitochondrial oocyte and embryo disturbances, or to the abnormal endocrine, metabolic and inflammatory uterine environment induced by obesity, which seems to be also responsible for other numerous complications during pregnancy and the in-utero fetal programming of postnatal diseases. A displacement of the window of implantation in obese women undergoing artificial endometrial preparation has recently been described and may be related to the poorer embryo implantation rates and increased risk of miscarriage observed following fresh and frozen embryo transfers with autologous oocytes, and with donated ova in recipients with extremely high BMI.

SUMMARY

Female obesity is related to poorer outcome in natural and assisted conception, including an increased risk of miscarriage. Embryo morphology, assessed by conventional methods or by morphokinetics, does not seem to be affected by excess weight, with similar blastocyst formation and quality than normal weight women reported in IVF cycles. Embryo aneuploidy is not increased, and higher miscarriages rates are seen after euploid embryo transfer in obese women. Disturbances of the uterus or its environment induced by female obesity seem to be the most likely cause of the increased risk of miscarriage, although metabolomic, epigenetic or mitochondrial oocyte and embryo dysfunction cannot be ruled out as cannot congenital anomalies. In the context of all the above, weight reduction before pregnancy should be advised in obese women trying to become pregnant.

Effect of Paternal Diet on Spermatogenesis and Offspring Health: Focus on Epigenetics and Interventions with Food Bioactive Compounds

Infertility is a growing public health problem. Consumption of antioxidant bioactive food compounds (BFCs) that include micronutrients and non-nutrients has been highlighted as a potential strategy to protect against oxidative and inflammatory damage in the male reproductive system induced by obesity, alcohol, and toxicants and, thus, improve spermatogenesis and the fertility parameters. Paternal consumption of such dietary compounds could not only benefit the fathers but their offspring as well. Studies in the new field of paternal origins of health and disease show that paternal malnutrition can alter sperm epigenome, and this can alter fetal development and program an increased risk of metabolic diseases and breast cancer in adulthood. BFCs, such as ascorbic acid, α-tocopherol, polyunsaturated fatty acids, trace elements, carnitines, N-acetylcysteine, and coenzyme Q10, have been shown to improve male gametogenesis, modulate epigenetics of germ cells, and the epigenetic signature of the offspring, restoring offspring metabolic health induced by stressors during early life. This indicates that, from a father’s perspective, preconception is a valuable window of opportunity to start potential nutritional interventions with these BFCs to maximize sperm epigenetic integrity and promote adequate fetal growth and development, thus preventing chronic disease in adulthood.

Preconception lifestyle advice for people with infertility

BACKGROUND

Infertility is a prevalent problem that has significant consequences for individuals, families, and the community. Modifiable lifestyle factors may affect the chance of people with infertility having a baby. However, no guideline is available about what preconception advice should be offered. It is important to determine what preconception advice should be given to people with infertility and to evaluate whether this advice helps them make positive behavioural changes to improve their lifestyle and their chances of conceiving.

OBJECTIVES

To assess the safety and effectiveness of preconception lifestyle advice on fertility outcomes and lifestyle behavioural changes for people with infertility.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, CENTRAL, MEDLINE, Embase, PsycINFO, AMED, CINAHL, trial registers, Google Scholar, and Epistemonikos in January 2021; we checked references and contacted field experts to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), randomised cross-over studies, and cluster-randomised studies that compared at least one form of preconception lifestyle advice with routine care or attention control for people with infertility.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Primary effectiveness outcomes were live birth and ongoing pregnancy. Primary safety outcomes were adverse events and miscarriage. Secondary outcomes included reported behavioural changes in lifestyle, birth weight, gestational age, clinical pregnancy, time to pregnancy, quality of life, and male factor infertility outcomes. We assessed the overall quality of evidence using GRADE criteria.

MAIN RESULTS

We included in the review seven RCTs involving 2130 participants. Only one RCT included male partners. Three studies compared preconception lifestyle advice on a combination of topics with routine care or attention control. Four studies compared preconception lifestyle advice on one topic (weight, alcohol intake, or smoking) with routine care for women with infertility and specific lifestyle characteristics. The evidence was of low to very low-quality. The main limitations of the included studies were serious risk of bias due to lack of blinding, serious imprecision, and poor reporting of outcome measures. Preconception lifestyle advice on a combination of topics versus routine care or attention control Preconception lifestyle advice on a combination of topics may result in little to no difference in the number of live births (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.79 to 1.10; 1 RCT, 626 participants), but the quality of evidence was low. No studies reported on adverse events or miscarriage. Due to very low-quality evidence, we are uncertain whether preconception lifestyle advice on a combination of topics affects lifestyle behavioural changes: body mass index (BMI) (mean difference (MD) -1.06 kg/m², 95% CI -2.33 to 0.21; 1 RCT, 180 participants), vegetable intake (MD 12.50 grams/d, 95% CI -8.43 to 33.43; 1 RCT, 264 participants), alcohol abstinence in men (RR 1.08, 95% CI 0.74 to 1.58; 1 RCT, 210 participants), or smoking cessation in men (RR 1.01, 95% CI 0.91 to 1.12; 1 RCT, 212 participants). Preconception lifestyle advice on a combination of topics may result in little to no difference in the number of women with adequate folic acid supplement use (RR 0.98, 95% CI 0.95 to 1.01; 2 RCTs, 850 participants; I² = 4%), alcohol abstinence (RR 1.07, 95% CI 0.99 to 1.17; 1 RCT, 607 participants), and smoking cessation (RR 1.01, 95% CI 0.98 to 1.04; 1 RCT, 606 participants), on low quality evidence. No studies reported on other behavioural changes. Preconception lifestyle advice on weight versus routine care Studies on preconception lifestyle advice on weight were identified only in women with infertility and obesity. Compared to routine care, we are uncertain whether preconception lifestyle advice on weight affects the number of live births (RR 0.94, 95% CI 0.62 to 1.43; 2 RCTs, 707 participants; I² = 68%; very low-quality evidence), adverse events including gestational diabetes (RR 0.78, 95% CI 0.48 to 1.26; 1 RCT, 317 participants; very low-quality evidence), hypertension (RR 1.07, 95% CI 0.66 to 1.75; 1 RCT, 317 participants; very low-quality evidence), or miscarriage (RR 1.50, 95% CI 0.95 to 2.37; 1 RCT, 577 participants; very low-quality evidence). Regarding lifestyle behavioural changes for women with infertility and obesity, preconception lifestyle advice on weight may slightly reduce BMI (MD -1.30 kg/m², 95% CI -1.58 to -1.02; 1 RCT, 574 participants; low-quality evidence). Due to very low-quality evidence, we are uncertain whether preconception lifestyle advice affects the percentage of weight loss, vegetable and fruit intake, alcohol abstinence, or physical activity. No studies reported on other behavioural changes. Preconception lifestyle advice on alcohol intake versus routine care Studies on preconception lifestyle advice on alcohol intake were identified only in at-risk drinking women with infertility. We are uncertain whether preconception lifestyle advice on alcohol intake affects the number of live births (RR 1.15, 95% CI 0.53 to 2.50; 1 RCT, 37 participants; very low-quality evidence) or miscarriages (RR 1.31, 95% CI 0.21 to 8.34; 1 RCT, 37 participants; very low-quality evidence). One study reported on behavioural changes for alcohol consumption but not as defined in the review methods. No studies reported on adverse events or other behavioural changes. Preconception lifestyle advice on smoking versus routine care Studies on preconception lifestyle advice on smoking were identified only in smoking women with infertility. No studies reported on live birth, ongoing pregnancy, adverse events, or miscarriage. One study reported on behavioural changes for smoking but not as defined in the review methods.

AUTHORS' CONCLUSIONS

Low-quality evidence suggests that preconception lifestyle advice on a combination of topics may result in little to no difference in the number of live births. Evidence was insufficient to allow conclusions on the effects of preconception lifestyle advice on adverse events and miscarriage and on safety, as no studies were found that looked at these outcomes, or the studies were of very low quality. This review does not provide clear guidance for clinical practice in this area. However, it does highlight the need for high-quality RCTs to investigate preconception lifestyle advice on a combination of topics and to assess relevant effectiveness and safety outcomes in men and women with infertility.

High burden of cardiometabolic risk factors in spouses of Indian women with hyperglycaemia in pregnancy

AIM

To evaluate the burden and association of cardiometabolic risk factors in the spouses of women with and without hyperglycaemia in pregnancy.

METHODS

Women with (n = 204) and without (n = 197) hyperglycaemia in pregnancy, along with their spouses, participated in this cross-sectional study. The hyperglycaemia in pregnancy group included women with gestational diabetes and diabetes in pregnancy. A detailed questionnaire was completed for all participants (men and women), documenting relevant personal and medical history, along with biochemical investigations (men).

RESULTS

A total of 401 couples were evaluated at the time point during the pregnancy of 24.7 ± 5.2 gestational weeks (mean ± sd). Dysglycaemia (prediabetes or diabetes), overweight/obesity (BMI ≥25 kg/m² ) and metabolic syndrome were detected in 120 (58.9%), 123 (60.3%) and 98 spouses (48.3%) of women with hyperglycaemia in pregnancy, respectively. In the fully adjusted model, an increased risk of dysglycaemia [odds ratio 1.43 (95% CI 0.95-2.17); P = 0.088], overweight/obesity [odds ratio 1.49 (95% CI 0.98-2.27); P = 0.064] and metabolic syndrome [odds ratio 2.00 (95% CI 1.30-3.07); P = 0.001] was seen in the spouses of women with hyperglycaemia in pregnancy. The prevalence of these metabolic conditions was higher in spouses of women with diabetes in pregnancy compared to spouses of women with gestational diabetes mellitus.

CONCLUSIONS

A high burden of cardiometabolic risk factors was observed in the spouses of women with hyperglycaemia in pregnancy. The opportunity provided by pregnancy could be used by the healthcare system not only to improve the health of the woman and her offspring, but also her spouse.