Current knowledge of obesity's effects in the pre- and periconceptional periods and avenues for future research

Key Considerations for Studying the Effects of High-Fat Diet on the Nulligravid Mouse Endometrium

The obesity epidemic continues to increase, with half of US women predicted to be obese by 2030. Women with obesity are at increased risk for not only cardiovascular and liver disease, but also reproductive disorders. Although mouse models are useful in studying the effects of obesity, there is inconsistency in obesity-induction methods, diet composition, and mouse strains, and studies using female mice are limited. In this study, we sought to compare the effects of a 45% high-fat diet (HFD) versus a 60% HFD on the uterine estrous cycle of nulligravid C57BL/6J mice. For 22 weeks, we placed a total of 20 mice on either a 60% HFD, 45% HFD, or each HFD-matched control diet (CD). Both HFDs produced significant weight gain, with 60% HFD and 45% HFD gaining significant weight after 2 weeks and 15 weeks, respectively. Additionally, both HFDs led to glucose intolerance, fatty liver, and adipocyte hypertrophy. Mice fed 60% HFD displayed hyperphagia in the first 12 weeks of HFD treatment. Moreover, 60% HFD-treated mice had a longer estrous cycle length and an increased percentage of estrus stage samplings compared to CD-treated mice. Estrous cycle stage-controlled 60% HFD-treated mice displayed an increased estrogen-to-progesterone ratio and decreased ovarian corpora lutea compared to CD-treated mice, which may underlie the observed estrous cycle differences. There was no significant difference between diets regarding endometrial morphology or the percent of endometrial CD45+ immune cells. Our results indicate that consideration is needed when selecting a HFD-induced obesity mouse model for research involving female reproductive health.

Lupus progression deteriorates oogenesis quality in MRL/lpr mice

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the activation of the immune response against self antigens. Numerous reproductive complications, including reduced birth rate and complications for the mother and the fetus during pregnancy, have been observed in women with SLE. In the present study, we aimed to investigate the effect of SLE development on oocyte meiosis in lupus-prone mice. Lupus-prone MRL/lpr mice were used for the experiments: disease-free (4 weeks of age) and sick (20 weeks of age, virgin and postpartum). The immune response was monitored by flow cytometry, ELISpot, ELISA, and histology. Oocytes were analyzed by fluorescence microscopy based on chromatin, tubulin, and actin structures. The lupus-prone MRL/lpr mice developed age-dependent symptoms of SLE with increased levels of various autoantibodies, proteinuria, and renal infiltrates and a tendency for the immune response to worsen with changes in cell populations and the cytokine profile. The number and quality of oocytes were also affected, and the successful pregnancy rate of MRL/lpr mice was limited to only 60%. Isolated oocytes showed severe structural changes in all studied groups. Systemic alterations in immune homeostasis in SLE affect the quality of developing oocytes, which is evident from a young age. The data obtained is in line with the trend of reduced fertility in lupus-prone MRL/lpr mice. The phenomenon can be explained by changes in the microenvironment of the relevant organs and close connection between ovulation and inflammatory processes.

Association between visceral adipose tissue area and infertility: a cross-sectional analysis

RESEARCH QUESTION

Is intra-abdominal fat obesity associated with infertility?

DESIGN

This study analysed data from the 2013-2018 National Health and Nutrition Examination Survey, with a total of 3013 women enrolled. The participants were divided into two groups: infertility and non-infertility. Differences between the two groups were analysed using a weighted Student's t-test or Mann-Whitney U-test for continuous variables, or a weighted chi-squared test for categorical data. Visceral adipose tissue area (VATA) was assessed by dual-energy X-ray absorptiometry. The independent association between infertility and log VATA was assessed by weighted multivariate logistic regression models. Subgroup analyses were performed to assess the strength of the results. Interaction tests were used to examine whether covariates interacted with log VATA to influence infertility.

RESULTS

Log VATA was significantly higher in the infertility group compared with the non-infertility group (P < 0.001). After adjustment for potential confounders, the results of multivariate logistic regression analysis revealed that an increase in log VATA was associated with increased prevalence of female infertility (OR = 2.453, 95% CI 1.278-4.792). Subgroup analyses showed this association in individuals aged <35 years (P = 0.002), Mexican-Americans (P = 0.033), non-hypertensive individuals (P = 0.013) and non-diabetic individuals (P = 0.003).

CONCLUSIONS

An enlarged VATA is associated with increased risk of infertility. The direct effect of VATA on female infertility needs to be clarified further to provide a basis for future prevention and treatment of female infertility.

Polycystic Ovary Syndrome and Irritable Bowel Syndrome: Is There a Common Pathway?

OBJECTIVE

Little is known about how polycystic ovary syndrome (PCOS) is linked to irritable bowel syndrome (IBS). This study aimed to review the existing literature regarding the association between PCOS or its symptoms and complications with IBS.

METHODS

In this review, studies that investigated the proposed cross-link between features of PCOS and IBS were included. This review collectively focused on recent findings on the mechanism and novel insight regarding the association between IBS and PCOS in future clinical practice. An electronic search of PubMed, Scopus, Epistemonikos, Cochrane Library and Google Scholar was performed. We did not restrict the study setting and publication date.

RESULTS

The existing evidence has not completely answered the question of whether there is an association between PCOS and IBS and vice versa. Six case-control studies (793 women with PCOS and 547 women in the control group) directly assessed the association between PCOS and IBS. The prevalence of IBS among women with PCOS in these studies has ranged from 10% to 52% compared with 5%-50% in control groups. Evidence suggested the common pathways may have contributed to the interaction between IBS and PCOS, including metabolic syndrome, sex hormone fluctuation, dysregulation of neurotransmitters, psychological problems and environmental and lifestyle factors. To date, it is still ambiguous which of the mentioned components largely contributes to the pathogenesis of both.

CONCLUSION

Although limited evidence has shown a higher prevalence of IBS in women with PCOS, there are several potential, direct and common indirect pathways contributing to the development of both IBS and PCOS.

Normal weight obesity is associated with lower AFC and adverse IVF outcomes

Background

Body weight could be classified into underweight, normal weight and overweight according to percentage of body fat (%BF), and normal weight obesity (NWO) is defined as a normal BMI but a high %BF. While the impact of NWO in women fecundity remain unknow. Therefore, this study aimed to investigate the associations between %BF and reproductive outcomes among in vitro fertilization (IVF) women with normal BMI.

Methods

A total of 469 women were included in this study and were classified into low %BF, normal %BF and high %BF according to previous study. Multivariate generalized regression models were employed to evaluate the associations of %BF with ovarian reserve parameters, IVF outcomes and early pregnancy outcomes. We further run sensitivity analyses by restricted the analysis to young women and those only with tubal factor, respectively.

Results

About 32.2% of normal BMI women were misclassified according %BF, with 16.4% of them were low %BF and 15.8% were high %BF. The high %BF group had significantly lower antral follicle count (AFC) than normal %BF groups, and the AFC showed a tendency of decrease as %BF increased. In sensitivity analysis in young women, high %BF group also had significantly lower number of good-quality embryos when compared to normal %BF groups. The results expanded to all IVF outcomes when analysis restricted to tubal factor women.

Conclusion

In summary, misclassifications of body weight status based on BMI are common according to %BF, and NWO is associated with adverse reproductive outcomes.

Preconception Diet Interventions in Obese Outbred Mice and the Impact on Female Offspring Metabolic Health and Oocyte Quality

Obese individuals often suffer from metabolic health disorders and reduced oocyte quality. Preconception diet interventions in obese outbred mice restore metabolic health and oocyte quality and mitochondrial ultrastructure. Also, studies in inbred mice have shown that maternal obesity induces metabolic alterations and reduces oocyte quality in offspring (F1). Until now, the effect of maternal high-fat diet on F1 metabolic health and oocyte quality and the potential beneficial effects of preconception dietary interventions have not been studied together in outbred mice. Therefore, we fed female mice a high-fat/high-sugar (HF/HS) diet for 7 weeks and switched them to a control (CONT) or caloric-restriction (CR) diet or maintained them on the HF/HS diet for 4 weeks before mating, resulting in three treatment groups: diet normalization (DN), CR, and HF/HS. In the fourth group, mice were fed CONT diet for 11 weeks (CONT). HF/HS mice were fed an HF/HS diet from conception until weaning, while all other groups were then fed a CONT diet. After weaning, offspring were kept on chow diet and sacrificed at 11 weeks. We observed significantly elevated serum insulin concentrations in female HF/HS offspring and a slightly increased percentage of mitochondrial ultrastructural abnormalities, mitochondrial size, and mitochondrial mean gray intensity in HF/HS F1 oocytes. Also, global DNA methylation was increased and cellular stress-related proteins were downregulated in HF/HS F1 oocytes. Mostly, these alterations were prevented in the DN group, while, in CR, this was only the case for a few parameters. In conclusion, this research has demonstrated for the first time that a maternal high-fat diet in outbred mice has a moderate impact on female F1 metabolic health and oocyte quality and that preconception DN is a better strategy to alleviate this compared to CR.

Association between waist circumference and female infertility in the United States

BACKGROUND

Obesity has significant implications for fertility and reproductive health. However, evidences linking abdominal obesity to female infertility were limited and inconclusive. Our objective was to figure out the potential relationship between waist circumference (WC) and infertility among women of childbearing age in the United States using data from the National Health and Nutrition Examination Survey (NHANES).

METHODS

Our cross-sectional study included 3239 female participants aged 18-45 years. To explore the independent relationship between WC and female infertility, the weighted multivariable logistic regression and smoothed curve fitting were performed. Interaction and subgroup analyzes were then conducted for secondary analysis.

RESULTS

WC was positively associated with female infertility independent of BMI after adjusting for BMI and other potential confounders. In fully adjusted model, for every 1cm increase in waist circumference, the risk of infertility increased by 3% (OR = 1.03, 95% CI: 1.01-1.06). When WC was divided into five equal groups, women in the highest quintile had 2.64 times risk of infertility than that in the lowest quintile (OR = 2.64, 95% CI: 1.31-5.30). Smooth curve fitting revealed a non-linear but positively dose-dependent relationship between WC and female infertility. Furthermore, we found an inverted U-shaped relationship (turning point: 113.5 cm) between WC and female infertility in participants who had moderate recreational activities and a J-shaped relationship (turning point: 103 cm) between WC and female infertility in participants who had deficient recreational activities.

CONCLUSIONS

Waist circumference is a positive predictor of female infertility, independent of BMI. Moderate recreational activities can lower the risk of female infertility associated with abdominal obesity.

Associations between weight-adjusted-waist index and infertility: Results from NHANES 2013 to 2020

Female infertility is a significant problem for women of reproductive age worldwide. Obesity has been proven to pose a danger for infertility in women. Weight-adjusted waist circumference index (WWI) is a recently created biomarker of obesity, and this research aims to explore the relationship between female infertility and WWI. Data for this investigation were gathered from National Health and Nutrition Examination Survey. We used weighted multivariate logistic regression, subgroup analysis, interaction testing, and smoothed curve fitting to investigate the relationship between infertility and WWI. A total of 6333 women were included and 708 (11.18%) had infertility. It was discovered that women with higher WWI had increased probabilities of infertility (OR = 1.92, 95% CI: 1.42-2.59) adjusting for confounders. In addition, WWI was linked to increased chances of infertility in women aged 28 to 36 years (OR = 1.59, 95% CI: 1.28-1.97). According to the results of this cross-sectional survey, WWI is positively associated with infertility among adult females in the U.S. And it can help identify infertile women and may help reduce the risk of infertility.

The Impact of Obesity on Reproductive Health and Pregnancy Outcomes

Women carry the majority of the burden of our obesogenic surroundings, with a larger prevalence of obesity than males, a greater impact on fertility and treatment success, and increased maternal and perinatal morbidity and death. Obesity and its associated morbidity are now among our most pressing global health concerns. Women are more susceptible to gaining weight, which has reproductive, coronary, and emotional consequences. The current data on the negative consequences of obesity before conception (fertility issues, assisted reproductive treatment, polycystic ovary disease, overweight and obesity preventative measures, and emotional well-being), pregnancy (preventing excess gestational body weight, gestational diabetes, and preeclampsia, as well as labor and newborn health), and following delivery (the lactation process and breastfeeding, postnatal weight retention, and depressive symptoms) health is summarized. in this review. Along with this, underlying factors, consequences, and solutions to the obesity pandemic are investigated, as well as the mechanisms of obesity's effect on women and men, the epigenetic consequences of masculine obesity, its significant effects on reproductive results, and the implications of the loss of weight preceding to pregnancy as well as during pregnancy. This review suggests study methodologies that might assist in guiding attempts to enhance reproductive health and neonatal health in obese or overweight women.

Obesity and In Vitro Fertilization

Obesity is a highly prevalent chronic disease with a significant effect on reproductive-age women. The clinical implications of obesity on fertility and pregnancy are well studied citing ovulatory dysfunction, hormonal imbalances, higher miscarriage rates, and increased maternal and neonatal risks. For this reason, many patients with obesity seek reproductive specialists to help build their families. Despite this literature base, the effect of weight loss interventions prior to assisted reproductive technology (ART) is lacking. This review aims to outline the impact of obesity on ART, specifically in vitro fertilization (IVF). Response differences to treatment protocols compared with normal weight counterparts, limitations of access to care, and the mixed results of weight-reduction strategies prior to fertility treatment will be addressed. The known data surrounding benefits of lifestyle modification, pharmacologic therapies, and surgical interventions for obesity prior to IVF are outlined and found to emphasize a need for further research to determine the optimal approach for infertility patients with obesity.

Obesity and Miscarriage

Obesity affects nearly 40% of reproductive-aged women and has serious implications for women's overall and reproductive health. Women with an elevated body mass index (BMI) have higher rates of anovulation and irregular menses, lower success with fertility treatment, and significantly higher rates of pregnancy complications, such as hypertension/preeclampsia, gestational diabetes, and preterm delivery. Many studies have also shown an association between obesity and early pregnancy loss. However, the causal association between BMI and miscarriage has not been elucidated, likely due to the multifactorial effects that BMI may have on early pregnancy development. In addition, BMI as an isolated variable fails to capture other relevant confounding health risk factors, such as nutrition, physical activity, and insulin resistance. In this review, we will summarize the current literature demonstrating the association between BMI and miscarriage, highlight the research that attempts to explain the association, and finally provide data on therapeutic interventions to improve reproductive outcomes in women suffering from obesity and early pregnancy loss.

Neighborhood disadvantage is associated with decreased ovarian reserve in women with overweight and obesity

OBJECTIVE(S)

To evaluate the association between neighborhood disadvantage and ovarian reserve stratified by body mass index (BMI).

DESIGN

Cross-sectional cohort study.

SETTING

Single academic medical center.

PATIENT(S)

A total of 193 healthy reproductive-age women with regular menstrual cycles in the St. Louis, Missouri metropolitan area.

INTERVENTION(S)

Residence in a disadvantaged neighborhood.

MAIN OUTCOME MEASURE(S)

Ovarian reserve as assessed by ovarian antral follicle count (AFC) and serum anti-Müllerian hormone (AMH) concentration.

RESULT(S)

Women (n = 193) ranged from 20 to 44 years. The majority had overweight or obesity (59%, n = 117) with mean BMI of 28±7 kg/m2. Forty-eight women lived in the most disadvantaged neighborhood quartile, of which 75% had overweight or obesity, compared with 54% of the 145 women living in the 3 less disadvantaged neighborhood quartiles. When controlling for age, race, and smoking status, women with overweight or obesity living in the most disadvantaged neighborhoods had significantly lower AMH compared with those living in the less disadvantaged neighborhoods. Antral follicle count did not differ among women with overweight or obesity by neighborhood of residence. Neighborhood disadvantage was not associated with ovarian reserve by AFC or AMH in women with normal weight or underweight status.

CONCLUSION(S)

Living in a socioeconomically deprived area is associated with lower markers of ovarian reserve among women with an elevated BMI.

The predictive value of preoperative luteinizing hormone to follicle stimulating hormone ratio for ovulation abnormalities recovery after laparoscopic sleeve gastrectomy: A prospective cohort study

Introduction

Obesity-related ovulation abnormalities (OA) affect fertility. LSG is the most frequent bariatric operation. However, no research has identified a reliable indicator for predicting OA recovery after LSG. The purpose of this research was to examine the prognostic usefulness of preoperative the luteinizing hormone (LH) to follicle-stimulating hormone (FSH) ratio (LFR).

Methods

Our department conducted a prospective study from 2016 to 2021. Venous blood was typically tested 3 days before surgery to get the preoperative LFR. Descriptive data, preoperative and postoperative variables were also collected. Binary logistic regression related preoperative LFR with OA recovery. The receiver operating characteristic (ROC) curve evulated preoperative LFR's predictive capability.

Results

A total of 157 women with a complete follow-up of one year were included. LFR was the only factor linked with OA (P < 0.001). AUC (area under the ROC curve) = 0.915, cutoff = 1.782, sensitivity = 0.93, and specificity = 0.82.

Discussion

Overall, LSG has a favorable surgical result, with a %TWL of 66.082 ± 12.012 at 12 months postoperatively. Preoperative sexual hormone levels, as expressed by LFR, has the potential to predict the fate of OA following LSG at one year post-operatively.

Role of Obesity in Female Reproduction

Contemporary scientists need no "p value" and "relative risk" statistics to be exquisitely aware of the increasing prevalence of obesity and complications posed by obesity. It is now well recognized that obesity is strongly associated with type 2 diabetes, hypertension, vascular disease, tumors and reproductive disorders. Obese women show lower levels of gonadotropin hormones, reduced fecundity, higher miscarriage rates and poorer outcomes of in vitro fertilization, revealing that obesity affects female reproduction. In addition, adipose tissue contains special immune cells and obesity-induced inflammation is a chronic, low-grade inflammatory response. Herein, we mainly review detrimental influences of obesity in the complete process of female reproduction, including hypothalamic-pituitary-ovarian axis, oocyte maturation, embryo and fetal development. In the latter part, we view obesity-induced inflammation and discuss related epigenetic impact on female reproduction.

Free Fatty Acids from Type 2 Diabetes Mellitus Serum Remodel Mesenchymal Stem Cell Lipids, Hindering Differentiation into Primordial Germ Cells

Type 2 diabetes mellitus (T2DM) adversely affects the essential characteristics of adipose tissue-derived mesenchymal stem cells (AdMSCs). Given that T2DM is associated with an altered serum free fatty acid (FFA) profile, we examined whether diabetic serum FFAs influence the viability, differentiation, and fatty acid composition of the major lipid fractions of human AdMSCs in vitro. Serum FFAs were isolated from 7 diabetic and 10 healthy nondiabetic female individuals. AdMSCs were cultured and differentiated into primordial germ cell-like cells (PGCLCs) in the presence of either diabetic or nondiabetic FFAs. Cell viability was assessed using trypan blue staining. Cell differentiation was evaluated by measuring the PGCLC transcriptional markers Blimp1 and Stella. Lipid fractionation and fatty acid quantification were performed using thin-layer chromatography and gas-liquid chromatography, respectively. Both diabetic and nondiabetic FFAs significantly reduced the viability of PGCLCs. The gene expression of both differentiation markers was significantly lower in cells exposed to diabetic FFAs than in those treated with nondiabetic FFAs. Saturated fatty acids were significantly increased and linoleic acid was significantly decreased in the cellular phospholipid fraction after exposure to diabetic FFAs. In contrast, monounsaturated fatty acids were reduced and linoleic acid was elevated in the cellular triglyceride fraction in response to diabetic FFAs. Such an altered serum FFA profile in patients with T2DM reduces the proliferation and differentiation potential of AdMSCs, presumably due to the aberrant distribution of fatty acids into cell phospholipids and triglycerides.

Maternal metabolic health and fertility: we should not only care about but also for the oocyte!

Metabolic disorders due to obesity and unhealthy lifestyle directly alter the oocyte's microenvironment and impact oocyte quality. Oxidative stress and mitochondrial dysfunction play key roles in the pathogenesis. Acute effects on the fully grown oocytes are evident, but early follicular stages are also sensitive to metabolic stress leading to a long-term impact on follicular cells and oocytes. Improving the preconception health is therefore of capital importance but research in animal models has demonstrated that oocyte quality is not fully recovered. In the in vitro fertilisation clinic, maternal metabolic disorders are linked with disappointing assisted reproductive technology results. Embryos derived from metabolically compromised oocytes exhibit persistently high intracellular stress levels due to weak cellular homeostatic mechanisms. The assisted reproductive technology procedures themselves form an extra burden for these defective embryos. Minimising cellular stress during culture using mitochondrial-targeted therapy could rescue compromised embryos in a bovine model. However, translating such applications to human in vitro fertilisation clinics is not simple. It is crucial to consider the sensitive epigenetic programming during early development. Research in humans and relevant animal models should result in preconception care interventions and in vitro strategies not only aiming at improving fertility but also safeguarding offspring health.

Obese outbred mice only partially benefit from diet normalization or calorie restriction as preconception care interventions to improve metabolic health and oocyte quality

STUDY QUESTION

Can diet normalization or a calorie-restricted diet for 2 or 4 weeks be used as a preconception care intervention (PCCI) in Western-type diet-induced obese Swiss mice to restore metabolic health and oocyte quality?

SUMMARY ANSWER

Metabolic health and oocyte developmental competence was already significantly improved in the calorie-restricted group after 2 weeks, while obese mice that underwent diet normalization showed improved metabolic health after 2 weeks and improved oocyte quality after 4 weeks.

WHAT IS KNOWN ALREADY

Maternal obesity is linked with reduced metabolic health and oocyte quality; therefore, infertile obese women are advised to lose weight before conception to increase pregnancy chances. However, as there are no univocal guidelines and the specific impact on oocyte quality is not known, strategically designed studies are needed to provide fundamental insights in the importance of the type and duration of the dietary weight loss strategy for preconception metabolic health and oocyte quality.

STUDY DESIGN, SIZE, DURATION

Outbred female Swiss mice were fed a control (CTRL) or high-fat/high-sugar (HF/HS) diet. After 7 weeks, some of the HF mice were put on two different PCCIs, resulting in four treatment groups: (i) only control diet for up to 11 weeks (CTRL_CTRL), (ii) only HF diet for up to 11 weeks (HF_HF), (iii) switch at 7 weeks from an HF to an ad libitum control diet (HF_CTRL) and (iv) switch at 7 weeks from an HF to a 30% calorie-restricted control diet (HF_CR) for 2 or 4 weeks. Metabolic health and oocyte quality were assessed at 2 and 4 weeks after the start of the intervention (n = 8 mice/treatment/time point).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Changes in body weight were recorded. To study the impact on metabolic health, serum insulin, glucose, triglycerides, total cholesterol and alanine aminotransferase concentrations were measured, and glucose tolerance and insulin sensitivity were analyzed at PCCI Weeks 2 and 4. The quality of in vivo matured oocytes was evaluated by assessing intracellular lipid droplet content, mitochondrial activity and localization of active mitochondria, mitochondrial ultrastructure, cumulus cell targeted gene expression and oocyte in vitro developmental competence.

MAIN RESULTS AND THE ROLE OF CHANCE

Significant negative effects of an HF/HS diet on metabolic health and oocyte quality were confirmed (P < 0.05). HF_CTRL mice already showed restored body weight, serum lipid profile and glucose tolerance, similar to the CTRL_CTRL group after only 2 weeks of PCCI (P < 0.05 compared with HF_HF) while insulin sensitivity was not improved. Oocyte lipid droplet volume was reduced at PCCI Week 2 (P < 0.05 compared with HF_HF), while mitochondrial localization and activity were still aberrant. At PCCI Week 4, oocytes from HF_CTRL mice displayed significantly fewer mitochondrial ultrastructural abnormalities and improved mitochondrial activity (P < 0.05), while lipid content was again elevated. The in vitro developmental capacity of the oocytes was improved but did not reach the levels of the CTRL_CTRL mice. HF_CR mice completely restored cholesterol concentrations and insulin sensitivity already after 2 weeks. Other metabolic health parameters were only restored after 4 weeks of intervention with clear signs of fasting hypoglycemia. Although all mitochondrial parameters in HF_CR oocytes stayed aberrant, oocyte developmental competence in vitro was completely restored already after 2 weeks of intervention.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

In this study, we applied a relevant HF/HS Western-type diet to induce obesity in an outbred mouse model. Nevertheless, physiological differences should be considered when translating these results to the human setting. However, the in-depth study and follow-up of the metabolic health changes together with the strategic implementation of specific PCCI intervals (2 and 4 weeks) related to the duration of the mouse folliculogenesis (3 weeks), should aid in the extrapolation of our findings to the human setting.

WIDER IMPLICATIONS OF THE FINDINGS

Our study results with a specific focus on oocyte quality provide important fundamental insights to be considered when developing preconception care guidelines for obese metabolically compromised women wishing to become pregnant.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Flemish Research Fund (FWO-SB grant 1S25020N and FWO project G038619N). The authors declare there are no conflicts of interest.

Obesity: A Doorway to a Molecular Path Leading to Infertility

The dramatic rise in obesity has recently made it a global health issue. About 1.9 billion were overweight, and 650 million global populations were obese in 2016. Obese women suffer longer conception time, lowered fertility rates, and greater rates of miscarriage. Obesity alters hormones such as adiponectin and leptin, affecting all levels within the hypothalamic-pituitary-gonadal axis. Advanced glycation end products (AGEs) and monocyte chemotactic protein-1 (MCP-1) are inflammatory cytokines that may play an important role in the pathophysiology of ovarian dysfunction in obesity. In obese males, there are altered sperm parameters, reduced testosterone, increased estradiol, hypogonadism, and epigenetic modifications transmitted to offspring. The focus of this article is on the possible adverse effects on reproductive health resulting from obesity and sheds light on different molecular pathways linking obesity with infertility in both female and male subjects. Electronic databases such as Google Scholar, Embase, Science Direct, PubMed, and Google Search Engine were utilized to find obesity and infertility-related papers. The search strategy is detailed in the method section. Even though multiple research work has shown that obesity impacts fertility in both male and female negatively, it is significant to perform extensive research on the molecular mechanisms that link obesity to infertility. This is to find therapeutics that may be developed aiming at these mechanisms to manage and prevent the negative effects of obesity on the reproductive system.

Effects of an obesogenic diet on the oviduct depend on the duration of feeding

Research question

How long does it take for an obesogenic (high-fat/high-sugar, HF/HS) diet to influence the oviductal microenvironment? What are the affected cellular pathways and are they dependent on the genetic background of the mouse model?

Design

Female Swiss (outbred) and C57BL/6N (B6, inbred) mice were fed either a control (10% fat) or HF/HS (60% fat, 20% fructose) diet. Body weight was measured weekly. Mice were sacrificed at 3 days (3d), 1 week (1w), 4w, 8w, 12w and 16w on the diet (n = 5 per treatment per time point). Total cholesterol concentrations and inflammatory cytokines were measured in serum. Oviductal epithelial cells (OECs) were used to study the expression of genes involved in (mitochondrial) oxidative stress (OS), endoplasmic reticulum (ER) stress and inflammation using qPCR.

Results

Body weight and blood cholesterol increased significantly in the HF/HS mice in both strains compared to controls. In Swiss mice, HF/HS diet acutely increased ER-stress and OS-related genes in the OECs already after 3d. Subsequently, mitochondrial and cytoplasmic antioxidants were upregulated and ER-stress was alleviated at 1w. After 4-8w (mid-phase), the expression of ER-stress and OS-related genes was increased again and persisted throughout the late-phase (12-16w). Serum inflammatory cytokines and inflammatory marker-gene expression in the OECs were increased only in the late-phase. Some of the OEC stress responses were stronger or earlier in the B6.

Conclusions

OECs are sensitive to an obesogenic diet and may exhibit acute stress responses already after a few days of feeding. This may impact the oviductal microenvironment and contribute to diet-induced subfertility.

The Role of Glp-1 Receptor Agonists in Insulin Resistance with Concomitant Obesity Treatment in Polycystic Ovary Syndrome

Insulin resistance is documented in clamp studies in 75% of women with polycystic ovary syndrome (PCOS). Although it is not included in the diagnostic criteria of PCOS, there is a crucial role of this metabolic impairment, which along with hormonal abnormalities, increase each other in a vicious circle of PCOS pathogenesis. Insulin resistance in this group of patients results from defects at the molecular level, including impaired insulin receptor-related signaling pathways enhanced by obesity and its features: Excess visceral fat, chronic inflammation, and reactive oxygen species. While lifestyle intervention has a first-line role in the prevention and management of excess weight in PCOS, the role of anti-obesity pharmacological agents in achieving and maintaining weight loss is being increasingly recognized. Glucagon-like peptide-1 receptor agonists (GLP1-RAs) not only act by reducing body weight but also can affect the mechanisms involved in insulin resistance, like an increasing expression of glucose transporters in insulin-dependent tissues, decreasing inflammation, reducing oxidative stress, and modulating lipid metabolism. They also tend to improve fertility either by increasing LH surge in hypothalamus-pituitary inhibition due to estrogen excess connected with obesity or decreasing too high LH levels accompanying hyperinsulinemia. GLP1-RAs seem promising for effective treatment of obese PCOS patients, acting on one of the primary causes of PCOS at the molecular level.

Elevated Body Mass Index in Donor Oocyte Recipients Does Not Affect Implantation of Euploid Embryos

Background: Obesity is a worldwide epidemic that has been shown to have serious implications on health outcomes. Regarding reproductive health, increased body mass index (BMI) reduces fertility and increases the time to conceive. It is unclear how excess weight in females affects the development of oocytes and embryos or the impact of implantation. Materials and Methods: This retrospective single-center study aimed to determine if overweight and obese oocyte recipients had similar pregnancy outcomes compared with healthy weight controls after the transfer of a single euploid frozen-thawed embryo transfer (FET). Five hundred twenty-eight patients who underwent a transfer from 2016 to 2021 were included. The primary outcome studied was the clinical pregnancy (CP) rate. Secondary outcomes included live birth (LB) rate, biochemical pregnancy loss (BPL) rate, and clinical pregnancy loss (CPL) rate. Results: The overall CP rate was 54.9% and did not differ significantly among normal weight (n = 318), overweight (n = 129), and obese (n = 81) BMI categories (0.56 vs. 0.56 vs. 0.49, p = 0.56). There were no significant differences in LB rate (0.47 vs. 0.43 vs. 0.38, p = 0.33), BPL rate (0.14 vs. 0.09 vs. 0.11, p = 0.59), and CPL rate (0.15 vs. 0.21 vs. 0.18, p = 0.38) among BMI groups. Conclusions: Our findings provide support that BMI alone does not adversely alter endometrial receptivity and is not the cause of poor in vitro fertilization (IVF) outcomes in patients with increased BMI. These deleterious IVF outcomes might be to the result of diminished oocyte and/or embryo quality or other factors that have not yet been elucidated.

Effect of Female and Male Body Mass Index on Cumulative Live Birth Rates in the Freeze-all Strategy

CONTEXT

The impact of parental overweight/obese on cumulative live birth rate in in vitro fertilization/intracytoplasmic sperm injection using a freeze-all strategy is still unknown.

OBJECTIVE

To explore the effect of parental body mass index (BMI) on cumulative live birth rate (CLBR) in a freeze-all strategy over 1.5 years.

METHODS

This was a retrospective study in a tertiary care academic medical center; 23 482 patients (35 289 frozen-thawed embryo transfer cycles) were divided into 4 groups according to Asian BMI classification. The main outcome measure was CLBR.

RESULTS

Female overweight/obesity had a lower tendency in CLBR (groups 1-4: optimistic: 69.4%, 67.9%, 62.3%, and 65.7%; conservative: 62.9%, 61.1%, 55.4%, and 57.6%) and prolonged time (groups 1-4: 11.0, 12.2, 15.9, and 13.8 months for 60% CLBR in the optimistic method; 8.7, 9.5, 11.7, 11.0 months for 50% CLBR in the conservative method). The same trend to a lesser extent was also observed in male BMI groups. When combining parental BMI, "parental overweight/obesity" had lower CLBR and longer time for reaching CLBR >50% (optimistic: 4.5 months for 60% CLBR; conservative: 3 months for 50% CLBR), followed by "only female high BMI" (optimistic: 2.1 months for 60% CLBR; conservative: 1.7 months for 50% CLBR), while "only male high BMI" had no influence.

CONCLUSION

Our results showed the importance of parental BMI, female BMI, and male BMI on the 1.5-year CLBR using a freeze-all strategy; the time to reach the CLBR (60% in optimistic, 50% in conservative) for overweight and obese patients was several months, but it is not as long as losing weight.

Metabolic risk factors and fertility disorders: A narrative review of the female perspective

Metabolic risk factors such as obesity are considered major obstacles to female fertility. Chronic infertility imposes psychological and social burdens on women because infertility violates societal gender roles. Although the prevalence of obesity among women is expected to increase in the future, the relevance of metabolic status for fertility is still underestimated. However, the assessment of metabolic risk factors is highly relevant for understanding fertility disorders and improving infertility treatment. This narrative review discusses the associations of metabolic risk factors (e.g. obesity, female athlete triad, oxidative stress) with significant infertility. An electronic search was conducted for studies published between 2006 and 2020 in Cumulative Index to Nursing and Allied Health Literature, ScienceDirect, PubMed, Scopus, Google Scholar and related databases. In total, this search identified 19,309 results for polycystic ovary syndrome, 28,969 results for endometriosis, and only 1611 results for idiopathic and/or unknown infertility. For the present narrative review, 50 relevant studies were included: 19 studies were on obesity, 24 studies investigated the female athlete triad, and seven studies addressed other risk factors, including reactive oxygen species. This narrative review confirms the direct impact of obesity on female infertility, while the effect of other risk factors needs to be confirmed by large-scale population studies.

Abnormal BMI in Male and/or Female Partners Are Deleterious for Embryonic Development and Pregnancy Outcome During ART Process: A Retrospective Study

OBJECTIVE

To investigate the effect of BMI in male and/or female partners on embryo development and clinical pregnancy outcome during ART.

METHODS

Data of 11,130 cycles between January 2018 and December 2020 were retrospectively analyzed. They were divided into Group A, B, C, and D based on couples' BMI values, also were divided into Group I, II, III and IV in IVF cycles and Group i, ii, iii, and iv in ICSI cycles. After grouping, inter-group indicators comparisons and logistic regression analysis were performed.

RESULTS

In IVF cycles, CPR in Group I and Group III were higher than Group IV. In Group III, it was higher than Group II. The AR in Group IV was higher, but the LBR was lower than Group I, Group II, and Group III. Logistic regression analysis results suggested that AR in Group IV was higher than that in Group I in IVF cycles, whereas LBR was lower.In ICSI cycles, high-quality embryo rate in Group i and Group ii were both higher than that in Group iii and Group iv. The CPR in Group i was higher than Group ii and Group iv, and in Group iii was higher than Group ii and Group iv. The AR in Group i was lower than Group iii and Group iv, and AR in Group ii was lower than Group iv. LBR, in Group I it was higher than Group ii, Group iii, and Group iv. Logistic regression analysis results suggested CPR in Group ii was significantly lower than that in Group i. AR in Group iii was considerably higher than that in Group i. LBR in Group ii and Group iv were significantly lower than that in Group i.

CONCLUSION

Female higher BMI was not conducive to the formation of high-quality embryos in ICSI cycle. Female and/or male BMI affected AR and LBR more than CPR not only in IVF cycles, but also in ICSI cycles.

Essentiality of Trace Elements in Pregnancy, Fertility, and Gynecologic Cancers-A State-of-the-Art Review

Gynecological neoplasms pose a serious threat to women's health. It is estimated that in 2020, there were nearly 1.3 million new cases worldwide, from which almost 50% ended in death. The most commonly diagnosed are cervical and endometrial cancers; when it comes to infertility, it affects ~48.5 million couples worldwide and the number is continually rising. Ageing of the population, environmental factors such as dietary habits, environmental pollutants and increasing prevalence of risk factors may affect the reproductive potential in women. Therefore, in order to identify potential risk factors for these issues, attention has been drawn to trace elements. Trace mineral imbalances can be caused by a variety of causes, starting with hereditary diseases, finishing with an incorrect diet or exposure to polluted air or water. In this review, we aimed to summarize the current knowledge regarding trace elements imbalances in the case of gynecologic cancers as well as female fertility and during pregnancy.

Obesity and oocyte quality: Significant implications for ART and Emerging mechanistic insights

The prevalence of obesity in adults worldwide, and specifically in women of reproductive age, is concerning given the risks to fertility posed by the increased risk of type 2 diabetes, metabolic syndrome and other non-communicable diseases. Obesity has a multi-systemic impact in female physiology that is characterized by the presence of oxidative stress, lipotoxicity, and the activation of pro-inflammatory pathways, inducing tissue-specific insulin resistance and ultimately conducive to abnormal ovarian function. A higher body mass is linked to Polycystic Ovary Syndrome, dysregulated menstrual cycles, anovulation, and longer time to pregnancy, even in ovulatory women. In the context of ART, compared to women of normal BMI, obese women have worse outcomes in every step of their journey, resulting in reduced success measured as live birth rate. Even after pregnancy is achieved, obese women have a higher chance of miscarriage, gestational diabetes, pregnancy complications, birth defects, and most worryingly, a higher risk of stillbirth and neonatal death. The potential for compounding effects of ART on pregnancy complications and infant morbidities in obese women has not been studied. There is still much debate in the field on whether these poorer outcomes are mainly driven by defects in oocyte quality, abnormal embryo development or an unaccommodating uterine environment, however the clinical evidence to date suggests a combination of all three are responsible. Animal models of maternal obesity shed light on the mechanisms underlaying the effects of obesity on the peri-conception environment, with recent findings pointing to lipotoxicity in the ovarian environment as a key driver of defects in oocytes that have not only reduced developmental competence but long-lasting effects in offspring health.

Diet normalization or caloric restriction as a preconception care strategy to improve metabolic health and oocyte quality in obese outbred mice

BACKGROUND

Maternal metabolic disorders are linked to reduced metabolic health and oocyte quality. Obese women are advised to lose weight before conception to increase pregnancy chances. However, as human studies show no univocal guidelines, more research is necessary to provide fundamental insights in the consequences of dietary weight loss on oocyte quality. Therefore, we investigated the impact of diet normalization or calorie restricted diet for two, four or six weeks, as preconception care intervention (PCCI), in obese mice on metabolic health and oocyte quality.

METHODS

Outbred female mice were fed a control (CTRL) or high-fat (HF) diet for 7 weeks (7w). Afterwards, HF-mice were put on different PCCIs, resulting in four treatment groups: 1) control diet up to 13w, 2) HF diet up to 13w (HF_HF), switch from a HF (7w) to 3) an ad libitum control diet (HF_CTRL) or 4) 30% calorie restricted control diet (HF_CR) for two, four or six weeks. Body weight, metabolic health, oocyte quality and overall fertility results were assessed.

RESULTS

Negative effects of HF diet on metabolic health, oocyte quality and pregnancy rates were confirmed. HF_CTRL mice progressively improved insulin sensitivity, glucose tolerance, serum insulin and cholesterol from PCCI w2 to w4. No further improvements in metabolic health were present at PCCI w6. However, PCCI w6 showed best oocyte quality improvements. Mature oocytes still showed elevated lipid droplet volume and mitochondrial activity but a significant reduction in ROS levels and ROS: active mitochondria ratio compared with HF_HF mice. HF_CR mice restored overall insulin sensitivity and glucose tolerance by PCCI w4. However, serum insulin, cholesterol and ALT remained abnormal. At PCCI w6, glucose tolerance was again reduced. However, only at PCCI w6, oocytes displayed reduced ROS levels and restored mitochondrial activity compared with HF_HF mice. In addition, at PCCI w6, both PCCI groups showed decreased mitochondrial ultrastructural abnormalities compared with the HF_HF group and restored pregnancy rates.

CONCLUSIONS

Diet normalization for 4 weeks showed to be the shortest, most promising intervention to improve metabolic health. Most promising improvements in oocyte quality were seen after 6 weeks of intervention in both PCCI groups. This research provides fundamental insights to be considered in developing substantiated preconception guidelines for obese women planning for pregnancy.

The effect of short term exposure to outdoor air pollution on fertility

BACKGROUND

There is evidence to suggest that long term exposure to air pollution could be associated with decreased levels of fertility, although there is controversy as to how short term exposure may compromise fertility in IVF patients and what windows of exposure during the IVF process patients could be most vulnerable.

METHODS

This prospective cohort study aimed to evaluate the impact of acute exposure that air pollution have on reproductive outcomes in different moments of the IVF process. Women undergoing IVF living in Barcelona were recruited. Individual air pollution exposures were modelled at their home address 15 and 3 days before embryo transfer (15D and 3D, respectively), the same day of transfer (D0), and 7 days after (D7). The pollutants modelled were: PM_2.5 [particulate matter (PM) ≤2.5 μm], PM_coarse (PM between 2.5 and 10μm), PM₁₀ (PM≤10 μm), PM_2.5 abs, and NO₂ and NOx. Outcomes were analyzed using multi-level regression models, with adjustment for co-pollutants and confouding factors. Two sensitivity analyses were performed. First, the model was adjusted for subacute exposure (received 15 days before ET). The second analysis was based on the first transfer performed on each patient aiming to exclude patients who failed previous transfers.

RESULTS

One hundred ninety-four women were recruited, contributing with data for 486 embryo transfers. Acute and subacute exposure to PMs showed a tendency in increasing miscarriage rate and reducing clinical pregnancy rate, although results were not statistically significant. The first sensitivity analysis, showed a significant risk of miscarriage for PM_2.5 exposure on 3D after adjusting for subacute exposure, and an increased risk of achieving no pregnancy for PM_2.5, PM_coarse and PM₁₀ on 3D. The second sensitivity analysis showed a significant risk of miscarriage for PM_2.5 exposure on 3D, and a significant risk of achieving no pregnancy for PM2.5, PM_coarse and PM10 particularly on 3D. No association was observed for nitrogen dioxides on reproductive outcomes.

CONCLUSIONS

Exposure to particulate matter has a negative impact on reproductive outcomes in IVF patients. Subacute exposure seems to increase the harmful effect of the acute exposure on miscarriage and pregnancy rates. Nitrogen dioxides do not modify significantly the reproductive success.

The Combined Impact of Female and Male Body Mass Index on Cumulative Pregnancy Outcomes After the First Ovarian Stimulation

Objectives

To evaluate the combined impact of male and female BMI on cumulative pregnancy outcomes after the first ovarian stimulation.

Design

Retrospective cohort study.

Setting

University-affiliated reproductive medicine center.

Patients

A total of 15,972 couples undergoing their first ovarian stimulations from June 2009 to June 2016 were included. During the follow-up period between June 2009 and June 2018, 14,182 couples underwent a complete ART cycle involving fresh embryo transfer and subsequent frozen embryo transfers (FETs) after their first ovarian stimulations. Patients with a BMI <24 kg/m2 served as the reference group. Patients with a BMI ≥ 24 kg/m2 were considered to be overweight, and those with a BMI ≥28 kg/m2 were considered to be obese.

Interventions

None.

Primary Outcome Measure

The primary outcome was the cumulative live birth rate (CLBR), which defined as the delivery of at least one live birth in the fresh or in the subsequent FET cycles after the first ovarian stimulation.

Results

In the analyses of females and males separately, compared with the reference group, overweight and obese females had a reduced CLBR (aOR 0.83, 95% CI 0.7.92 and aOR 0.76, 95% CI 0.64-0.90). Similarly, overweight males had a reduced CLBR (aOR 0.91, 95% CI 0.83-0.99) compared with that of the reference group. In the analyses of couples, those in which the male was in the reference or overweight group and the female was overweight or obese had a significantly lower CLBR than those in which both the male and female had a BMI <24 kg/m2.

Conclusions

The CLBR is negatively impacted by increased BMI in the female and overweight status in the male, both individually and together.

Association between abnormal body mass index and pregnancy outcomes in patients following frozen embryo transfer: a systematic review and meta-analysis

BACKGROUND

There has been increasing interest in the relationship between body mass index(BMI) and pregnancy outcomes, especially in women undergoing frozen embryo transfer(FET). Several observational studies have been published, but so far with conflicting results.

METHODS

A systematic review and meta-analysis was conducted according to PRISMA guidelines. Pubmed, Embase, Cochrane Library, Clinicaltrails.gov and Web of Science databases were searched based on established search strategy from inception through January 2021.

RESULTS

Twelve studies were eligible. In women following FET, high BMI (BMI ≥ 23 kg/m²) was associated with an impaired live birth rate (LBR, OR: 0.89, 95% CI: 0.82-0.96, P = 0.002), but wasn't associated with the implantation rate or the clinical pregnancy rate. Subgroup analysis revealed higher LBR for women didn't complicated by polycystic ovary syndrome (PCOS, OR: 0.96, 95% CI: 0.85-1.08, P = 0.46) and women with blastocyst transferred (OR: 0.89, 95% CI: 0.68-1.16, P = 0.40). LBR did not differ between the low BMI group (BMI < 18.5 kg/m²) and the normal weight group.

CONCLUSIONS

Our study showed that high BMI in women is negatively associated with LBR in FET cycles, whereas low BMI isn't. The results of subgroup analysis implied a need for women with a high BMI to get individualized weight management and treatment. Further evidence is still required to optimize preconception health and develop Nutritional and exercise guidelines.

Overweight and obesity significantly reduce pregnancy, implantation, and live birth rates in women undergoing In Vitro Fertilization procedures

OBJECTIVE

The objective of this study was to evaluate the effects of overweight and obesity on fertility outcomes in IVF procedures.

METHODS

This was a retrospective and nonrandomized study that included 191 IVF/ICSI cycles using non-donor oocytes performed between July 2016 and December 2018 that were allocated according to Body Mass Index (BMI) in three groups: Normal group: 18.5-24.9 (n=67 women), Overweight group: 25.0-29.9 (n=86 women) and Obesity group: ≥30.0 (n=38 women). We compared fertilization rates, embryo quality at day 3, development and quality of blastocyst, pregnancy rates, implantation rates, and live birth rates.

RESULTS

Patients from all groups had similar stimulation days, but those women with overweight and obesity used more hormones compared to women with normal weight (p<0.05). Fertilization rates, zygotes that underwent cleavage and good-quality embryos at Day 3 were similar between the three evaluated groups. The groups of overweight and obesity had embryos at Day 3 with significantly less cells, compared to those from the normal group (p<0.05). The blastocyst development rate was significantly lower in women with overweight and obesity compared to women with normal BMI (p<0.05); but, the percentages of good blastocysts were similar in all studied patients. Pregnancy, implantation and live birth rates were significantly lower in the group of women with overweight and obesity, compared to those women with normal weight (p<0.05). Obese women had significantly more miscarriages compared to those in the other groups (p<0.05).

CONCLUSIONS

Our data shows that an increased BMI affects embryo development and significantly reduces the pregnancy, implantation and live birth rates.

Change in Birth Rate Before and After Bariatric Surgery in France

IMPORTANCE

Bariatric surgery worldwide has grown significantly over the past years and is performed, in a vast majority, in women of childbearing age. The impact of these procedures on birth rates remains largely unknown.

OBJECTIVE

The main objective was to study the evolution of the birth rates in these women, before and after bariatric surgery and in comparison with women from the general population. The secondary objectives were to compare the birth rates before and after surgery according to the Body Mass Index (BMI) (BMI 40-50 versus >50 kg/m²).

METHOD

Our analyses are based on a national medico-administrative database. All women of childbearing age and who had bariatric surgery between 2012 and 2016 were included, and we included all deliveries between 2012 and 2018 in this population. We compared the birth rates before and after bariatric surgery. National statistics (INSEE, Institut National de la Statistique et des Etudes Economiques) were used for comparison with women from the general population.

FINDINGS

A total of 69,932 women were included between 2012 and 2016, with a median age at surgery of 33 years [27; 39]. Among them, 9391 (13%) had a BMI over 50 kg/m² before surgery, 46,818 (67%) benefited from a sleeve gastrectomy (SG), and 23,376 (33%) from a gastric bypass (GBP). Birth rates tend to be smaller after surgery compared to before surgery for women under 27 years (OR: 0.92, CI95% [0.88; 0.96]), while being not different after 27 in both groups (OR: 1.00, CI95% [0.97; 1.03]). Birth rates of obese women who have benefited or will benefit from the bariatric surgery were higher than the general population, with a peak at a younger age, and then decline earlier than the general population. Trends were different according to BMI class. Birth rates were higher for women with BMI between 40 and 50 kg/m² compared to women with BMI greater than 50 kg/m² (OR=1.28, CI95% [1.21; 1.36]) before surgery while slightly lower after surgery (OR=0.95, CI95% [0.91; 0.99]).

CONCLUSIONS AND RELEVANCE

We showed that birth rates after bariatric surgery were not different before and after bariatric surgery except for women under 27 years old who had a smaller birth rate. Interestingly, we observed an improvement of birth rates after surgery for women with a BMI of 50 kg/m² or more.

The More Fertile, the More Creative: Changes in Women's Creative Potential across the Ovulatory Cycle

Creative thinking is a defining human feature. It provides novel solutions and as such undoubtedly has contributed to our survival. However, according to signaling theory, creativity could also have evolved through sexual selection as a potential fitness indicator. In our study, we tested one implication of this theory. Specifically, we hypothesized that if creativity can serve as a signal of women’s fitness, then we should observe an increase in creative thinking in the fertile phase of the ovulatory cycle compared to other non-fertile phases. In our study (N = 751), we tested creative potential throughout the ovulatory cycle. We found a positive correlation between the probability of conception and both creative originality and flexibility. Importantly, we also tested the mediating role of arousal in the relationship between the probability of conception and creative thinking. The results of our study are discussed in terms of signaling theory, through which women advertise their fitness with their creativity.

Trimethylamine-N-oxide is present in human follicular fluid and is a negative predictor of embryo quality

STUDY QUESTION

Are levels of trimethylamine-N-oxide (TMAO) in human follicular fluid (FF) related to IVF outcomes?

SUMMARY ANSWER

Higher levels of TMAO are a negative predictor of oocyte fertilization and embryo quality.

WHAT IS KNOWN ALREADY

TMAO is a metabolic product of dietary choline and l-carnitine produced via subsequent enzymatic modifications by the intestinal microbiota and hepatocytes. TMAO promotes inflammatory and oxidative stress pathways and has been characterized as a causative biomarker for the development of cardiometabolic disease.

STUDY DESIGN, SIZE, DURATION

For the present cross-sectional study, samples (FF and plasma) from 431 modified natural cycle (MNC)-IVF cycles of 132 patients were collected prospectively between October 2014 and March 2018 in a single academic medical center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

TMAO and its precursors (choline, l-carnitine and gamma-butyrobetaine) were measured by ultra-high-performance liquid chromatography/mass spectrometry in (i) matched FF and plasma from 63 MNC-IVF cycles, in order to compare metabolite levels in the two matrices and (ii) FF from 232 MNC-IVF cycles in which only one oocyte was retrieved at follicular puncture. The association between metabolite levels and oocyte fertilization, embryo fragmentation percentage, embryo quality and the occurrence of pregnancy was analyzed using multilevel generalized estimating equations with adjustment for patient and cycle characteristics.

MAIN RESULTS AND THE ROLE OF CHANCE

The level of choline was higher in FF as compared to matched plasma (P < 0.001). Conversely, the levels of TMAO and gamma-butyrobetaine were lower in FF as compared to plasma (P = 0.001 and P = 0.075, respectively). For all metabolites, there was a positive correlation between FF and plasma levels. Finally, levels of TMAO and its gut-derived precursor gamma-butyrobetaine were lower in FF from oocytes that underwent normal fertilization (TMAO: odds ratio [OR] 0.66 [0.49–0.90], P = 0.008 per 1.0-μmol/L increase; gamma-butyrobetaine: OR 0.77 [0.60–1.00], P = 0.047 per 0.1-μmol/L increase) and developed into top-quality embryos (TMAO: OR 0.56 [0.42–0.76], P < 0.001 per 1.0-μmol/L increase; gamma-butyrobetaine: OR 0.79 [0.62–1.00], P = 0.050 per 0.1-μmol/L increase) than in FF from oocytes of suboptimal development.

LIMITATIONS, REASONS FOR CAUTION

The individual contributions of diet, gut bacteria and liver to the metabolite pools have not been quantified in this analysis.

WIDER IMPLICATIONS OF THE FINDINGS

More research on the contribution of diet and the effect of gut bacteria on FF TMAO is warranted. Since TMAO integrates diet, microbiota and genetic setup of the person, our results indicate potential important clinical implications for its use as biomarker for lifestyle interventions to improve fertility.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was received for this project. The Department of Obstetrics and Gynecology of the University Medical Center Groningen received an unrestricted educational grant of Ferring Pharmaceutical BV, the Netherlands. The authors have no other conflicts of interest.

TRIAL REGISTRATION NUMBER

Netherlands Trial Register number NTR4409.

How to provide a structured clinical assessment of a patient with overweight or obesity

With the increasing prevalence of overweight and obesity worldwide, there is a reciprocal increase in the global economic burden and ill-health from obesity-related chronic diseases. Primary healthcare services have a role to play in ensuring early detection of weight issues and in directing patients towards evidence-based care to slow this progression. Research shows that many people with obesity are motivated to lose weight and want their clinician to initiate a conversation about weight management and treatment options. However, this conversation rarely occurs and there is a significant delay in treatment, resulting in an increased burden on the individual, healthcare system and society. In this paper, the components and rationale for the clinical assessment of adult patients with overweight or obesity, including anthropometric measurements and pathology tests, are described. Recommendations to ascertain the potential factors influencing the development of obesity in the patient, such as lifestyle factors (diet and physical activity) and mental health, are also provided. The potential sequelae of obesity that may be present and the necessary assessments for diagnosis are also addressed. These assessments are vital to ensure the patient is referred to the appropriate allied health services and/or specialists.

Development and Validation of a Clinical Pregnancy Failure Prediction Model for Poor Ovarian Responders During IVF/ICSI

BACKGROUNDS

Despite the great advances in assisted reproductive technology (ART), poor ovarian response (POR) is still one of the most challenging tasks in reproductive medicine. This predictive model we developed aims to predict the individual probability of clinical pregnancy failure for poor ovarian responders (PORs) under in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI).

METHODS

The nomogram was developed in 281 patients with POR according to the Bologna criteria from January 2016 to December 2019, with 179 in the training group and 102 in the validation group. Univariate and multivariate logistic regression analyses were used to identify characteristics that were associated with clinical pregnancy failure. The nomogram was constructed based on regression coefficients. Performance was evaluated using both calibration and discrimination.

RESULTS

Age >35 years, body mass index (BMI) >24 kg/m², basic follicle-stimulating hormone (FSH) >10 mIU/ml, basic E2 >60 pg/ml, type B or C of endometrium on human chorionic gonadotropin (hCG) day, and the number of high-quality embryos <2 were associated with pregnancy failure of POR patients. The area under the receiver operating characteristic curve (AUC) of the training set is 0.786 (95% confidence interval (CI): 0.710-0.861), and AUC in the validation set is 0.748 (95% CI: 0.668-0.827), showing a satisfactory goodness of fit and discrimination ability in this nomogram.

CONCLUSION

Our nomogram can predict the probability of clinical pregnancy failure in PORs before embryo transfer in IVF/ICSI procedure, to help practitioners make appropriate clinical decisions and to help infertile couples manage their expectations.

Risk Factors for Different Types of Pregnancy Losses: Analysis of 15,210 Pregnancies After Embryo Transfer

OBJECTIVE

To evaluate the risk factors for different types of pregnancy losses after embryo transfer (ET).

DESIGN

Retrospective cohort study.

SETTING

Reproductive medicine center.

PARTICIPANTS

A total of 15,210 pregnancies after fresh and frozen-thawed embryo transfer between January 2014 and June 2019.

MAIN OUTCOME MEASURES

The primary outcome was pregnancy loss (PL) throughout the entire pregnancy. Secondary outcomes were non-visualized PL, early miscarriage, late miscarriage, and stillbirth.

METHODS

The effect of patients' baseline characteristics and IVF/ICSI cycle-specific factors on the risk of PL after fresh and frozen-thawed ET was determined by multivariate logistic regression analysis.

RESULTS

Compared to women under 35 years old, those between 35 and 40 had an increased risk of early miscarriage [odds ratio (OR) 1.49, 95% confidence interval (CI) 1.22-1.83], while those after 40 appeared to have an increased risk of both early miscarriage (OR 3.82, 95% CI 2.65-5.51) and late miscarriage (OR 2.79, 95% CI 1.64-4.77). Overweight patients were observed to have a higher risk of late miscarriage (OR 1.38, 95% CI 1.16-1.65), while obese patients showed a higher risk of both early miscarriage (OR 1.47, 95% CI 1.14-1.91) and late miscarriage (OR 1.80, 95% CI 1.33-2.44). Polycystic ovary syndrome (PCOS) was an independent risk factor for late miscarriage (OR 1.58, 95% CI 1.28-1.96), and the detrimental effect of PCOS was independent of obesity status. Women with uterine factors had a higher risk of early miscarriage (OR 1.77 (95% CI 1.32-2.38) than women without uterine factors. A negative correlation was observed between the thickness of the endometrium and PL (OR 0.95 95% CI 0.92-0.97). There was an increased risk of PL after frozen-thawed ET versus fresh ET (OR 1.12, 95% CI 1.01-1.24). Women who transferred ≥2 embryos showed lower risk of overall PL than women who transferred a single embryo, with adjusted ORs ranged from 0.57~0.94. However, women who transferred three embryos demonstrated a higher risk of late miscarriage than women who transferred a single embryo (OR 2.23, 95% CI 1.36-3.66).

CONCLUSIONS

Patients with uterine factors demonstrated higher risk of early miscarriage and stillbirth. Being overweight, PCOS, and transferring three embryos was associated with late miscarriage. Being aged 40 and over, obese, and using frozen embryo transfer was associated with early and late miscarriage.

A 21st Century Epidemy-Obesity: And Its Impact on Pregnancy Loss

The prevalence of obesity among women of reproductive age is growing significantly over the last years. Being obese or having a high body mass index (BMI) contributes to many diseases and pregnancy complications. This is concerning as an obese woman is at increased risk for developing several complications during pregnancy and is at increased risk for pregnancy loss, stillbirth, and metabolic disorders of a live-born child in his future. The pregnant woman's body mass index has to be monitored well during the whole pregnancy, and their diet should also be monitored to avoid future complications. Better results can be achieved if every woman would watch their weight before being pregnant for better outcomes in their future pregnancies. This review article aimed to determine the relationship between being obese or having a high BMI and pregnancy loss. Additionally, we tried to find the mechanism that is involved in pregnancy loss in obese women. 

Single-cell transcriptome analysis reveals that maternal obesity affects DNA repair, histone methylation, and autophagy level in mouse embryos

Obesity causes many reproductive dysfunctions such as reduced conception, infertility, and early pregnancy loss, and this is largely due to the negative effects of obesity on oocyte and embryo quality. In the present study, we employed single-cell RNA transcriptome sequencing to investigate the potential causes for the maternal obesity effects on mouse embryos. Our results showed that the 4-cell and morula/blastocyst rates were all significantly decreased during embryo development in obese mice. Genome-wide analysis indicated that obesity altered the expression of more than 1100 genes in 2-cell embryos, including the genes which were related to the p53 signaling pathway and apoptosis. Further analysis showed that the expression of 47 genes related to DNA damage was changed, and a positive γH2A signal and the altered expression of Rad51 and Tex15 were observed in the obese embryos. Obesity also affected histone methylation, shown by the decrease of the H3K4-me2 level. Besides this, we observed the occurrence of autophagy and apoptosis in the embryos of obese mice. There were 42 genes that were related to autophagy/apoptosis that showed aberrant expression, and the positive LC3 signal and the decrease of Clec16a, Rraga, and Atg10 level were also observed. In summary, our study suggested that obesity affected early embryonic development by inducing DNA damage, aberrant histone methylation, and autophagy levels in mice.

Phycocyanin Improves Reproductive Ability in Obese Female Mice by Restoring Ovary and Oocyte Quality

Reproductive dysfunction associated with obesity is increasing among women of childbearing age. Emerging evidence indicates that maternal obesity impairs embryo development and offspring health, and these defects are linked to oxidative stress in the ovary and in oocytes. Phycocyanin (PC) is a biliprotein from Spirulina platensis that possesses antioxidant, anti-inflammatory, and radical-scavenging properties. Our previous studies have shown that PC can reduce reactive oxygen species (ROS) accumulation in oocytes in D-gal-induced aging mice. Here, at the Institute of Cancer Research (ICR) mice fed a high-fat diet (HFD) to model obesity were used to test the effect of PC on reversing the fertility decline caused by obesity. We observed a significant increase in litter size and offspring survival rates after PC administration to obese mice. Further, we found that PC not only ameliorated the level of ovarian antioxidant enzymes, but also reduced the occurrence of follicular atresia in obese female mice. In addition, the abnormal morphology of the spindle-chromosome complex (SCC), and the abnormal mitochondrial distribution pattern in oocytes both recovered. The obesity-related accumulation of ROS, increased number of early apoptotic cells, and the abnormal expression of H3K9me3 in oocytes were all partially reversed after PC administration. In summary, this is the first demonstration that PC can improve fertility by partially increasing ovarian and oocyte quality in obese female mice and provides a new strategy for clinically treating obesity-related infertility in females.

Obesity, Polycystic Ovary Syndrome, and Infertility: A New Avenue for GLP-1 Receptor Agonists

CONTEXT

Obesity is responsible for an increased risk of sub-fecundity and infertility. Obese women show poorer reproductive outcomes regardless of the mode of conception, and higher body mass index (BMI) is associated with poorer fertility prognosis. Polycystic ovary syndrome (PCOS) is one of the leading causes of infertility, and many women with PCOS are also overweight or obese.

EVIDENCE ACQUISITION

The aim of the present narrative review is to describe the mechanisms responsible for the development of infertility and PCOS in women with obesity/overweight, with a focus on the emerging role of glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) as a therapeutic option for obese women with PCOS.

EVIDENCE SYNTHESIS

Weight reduction represents the most significant factor affecting fertility and pregnancy outcomes. Current experimental and clinical evidence suggests the presence of an underlying pathophysiological link between obesity, GLP-1 kinetic alterations, and PCOS pathogenesis. Based on the positive results in patients affected by obesity, with or without diabetes, the administration of GLP-1 RA (mainly liraglutide) alone or in combination with metformin has been investigated in women with obesity and PCOS. Several studies demonstrated significant weight loss and testosterone reduction, with mixed results relative to improvements in insulin resistance parameters and menstrual patterns.

CONCLUSIONS

The weight loss effects of GLP-1 RA offer a unique opportunity to expand the treatment options available to PCOS patients.

A Shift in Glycerolipid Metabolism Defines the Follicular Fluid of IVF Patients with Unexplained Infertility

Follicular fluid (FF) constitutes the microenvironment of the developing oocyte. We recently characterized its lipid composition and found lipid signatures of positive pregnancy outcome after in vitro fertilization (IVF). In the current study, we aimed to test the hypothesis that unexplained female infertility is related to lipid metabolism, given the lipid signature of positive-outcome IVF patients we previously found. Assuming that FF samples from IVF patients with male factor infertility can represent a non-hindered metabolic microenvironment, we compared them to FF taken from women with unexplained infertility. FF from patients undergoing IVF was examined for its lipid composition. We found highly increased triacylglycerol levels, with a lower abundance of monoacylglycerols, phospholipids and sphingolipids in the FF of patients with unexplained infertility. The alterations in the lipid class accumulation were independent of the body mass index (BMI) and were altogether kept across the age groups. Potential lipid biomarkers for pregnancy outcomes showed a highly discriminative abundance in the FF of unexplained infertility patients. Lipid abundance distinguished IVF patients with unrecognized infertility and provided a potential means for the evaluation of female fertility.

The effect of excess body fat on female and male reproduction

The dramatic increase in the prevalence of obesity coincides with a decline in reproductive health indices in both sexes. Energy excess mediates changes to the regulatory mechanisms of the reproductive system. Obese individuals exhibit increased estrogen concentrations, due to the overexpression of aromatase in the adipose tissue; via a negative feedback loop, men present with symptoms of hypogonadotropic hypogonadism. These hormonal changes, along with increased oxidative stress, lipotoxicity and disturbances in the concentrations of adipokines, directly affect the gonads, peripheral reproductive organs and the embryo. Clinical evidence is somewhat contradicting, with only some studies advocating worse semen parameters, increased incidence of erectile dysfunction, increased doses of ovulation induction medications, and worse live birth rates in assisted reproductive technology (ART) cycles in obese individuals compared with those of normal weight. Similar conclusions are drawn about patients with insulin resistance syndromes, namely polycystic ovary syndrome (PCOS). As far as treatment options are concerned, lifestyle changes, medical therapy and bariatric surgery may improve the reproductive outcome, although the evidence remains inconclusive. In this review, we summarize the evidence on the association of obesity and reproductive health on both the molecular and the clinical level, and the effect of weight-loss interventions on reproductive potential.

Body mass index is not associated with donor oocyte recipient success: an ideal study using a paired analysis of sibling-oocytes

OBJECTIVE

To determine whether a higher body mass index (BMI) adversely affects endometrial receptivity.

DESIGN

Retrospective cohort study.

SETTING

Academic medical center.

PATIENTS

All donor egg recipients (DERs) who received fresh sibling-oocytes (oocytes from a donor that were retrieved from a single controlled ovarian hyperstimulation [COH] cycle and split between two recipients) at our center over a 7-year period were included.

INTERVENTIONS

COH of a donor with fresh embryo transfer to recipients of differing BMI. The two recipients of the sibling-oocytes were paired and categorized based on BMI: group A (normal weight, BMI 18.5-24.9 kg/m2) and group B (overweight/obese, BMI >25.0 kg/m2).

MAIN OUTCOME MEASURES

The primary outcome was implantation rate. Secondary outcomes were positive pregnancy rate and live birth rate.

RESULTS

A total of 408 patients had received oocytes from a split donor oocyte cycle. There were 71 pairs of patients (142 recipients) that had discrepant BMI categories and were analyzed. Implantation rates were similar for the two groups (54.5%±5.3% vs. 56.3%±4.8% for group A and B, respectively, P=0.72). The positive pregnancy rate (77.5% vs. 80.3%, P=0.28) and live birth rate (54.9% vs. 60.6%, P=0.33) for groups A and B were also found to be similar.

CONCLUSIONS

In this idealized model that controls to the greatest degree possible for factors that would impact implantation, we found that a higher BMI did not reduce implantation, positive pregnancy, or delivery rates. These findings suggest that a higher BMI does not adversely affect uterine receptivity.

Female obesity is negatively associated with live birth rate following IVF: a systematic review and meta-analysis

BACKGROUND

A worldwide increase in the prevalence of obesity has been observed in the past three decades, particularly in women of reproductive age. Female obesity has been clearly associated with impaired spontaneous fertility, as well as adverse pregnancy outcomes. Increasing evidence in the literature shows that obesity also contributes to adverse clinical outcomes following in vitro fertilization (IVF) procedures. However, the heterogeneity of the available studies in terms of populations, group definition and outcomes prevents drawing firm conclusions. A previous meta-analysis published in 2011 identified a marginal but significant negative effect of increased female body mass index (BMI) on IVF results, but numerous studies have been published since then, including large cohort studies from national registries, highlighting the need for an updated review and meta-analysis.

OBJECTIVE AND RATIONALE

Our systematic review and meta-analysis of the available literature aims to evaluate the association of female obesity with the probability of live birth following IVF. Subgroup analyses according to ovulatory status, oocyte origin, fresh or frozen-embryo transfer and cycle rank were performed.

SEARCH METHODS

A systematic review was performed using the following key words: ('obesity', 'body mass index', 'live birth', 'IVF', 'ICSI'). Searches were conducted in MEDLINE, EMBASE, Cochrane Library, Eudract and clinicaltrial.gov from 01 January 2007 to 30 November 2017. Study selection was based on title and abstract. Full texts of potentially relevant articles were retrieved and assessed for inclusion by two reviewers. Subsequently, quality was assessed using the Newcastle-Ottawa Quality Assessment Scales for patient selection, comparability and assessment of outcomes. Two independent reviewers carried out study selection and data extraction according to Cochrane methods. Random-effect meta-analysis was performed using Review Manager software on all data (overall analysis), followed by subgroup analyses.

OUTCOMES

A total of 21 studies were included in the meta-analysis. A decreased probability of live birth following IVF was observed in obese (BMI ≥ 30 kg/m2) women when compared with normal weight (BMI 18.5-24.9 kg/m2) women: risk ratio (RR) (95% CI) 0.85 (0.82-0.87). Subgroups analyses demonstrated that prognosis was poorer when obesity was associated with polycystic ovary syndrome, while the oocyte origin (donor or non-donor) did not modify the overall interpretation.

WIDER IMPLICATIONS

Our meta-analysis clearly demonstrates that female obesity negatively and significantly impacts live birth rates following IVF. Whether weight loss can reverse this deleterious effect through lifestyle modifications or bariatric surgery should be further evaluated.

Maternal obesogenic diet combined with postnatal exposure to high-fat diet induces metabolic alterations in offspring

Maternal obesity has been shown to impact the offspring health during childhood and adult life. This study aimed to evaluate whether maternal obesity combined with postnatal exposure to an obesogenic diet could induce metabolic alterations in offspring. Female CD1 mice were fed a control diet (CD, 11.1% of energy from fat) or with a high-fat diet (HFD, 44.3% of energy from fat) for 3 months. After weaning, pups born from control and obese mothers were fed with CD or HFD for 3 months. Both mothers and offspring were weighted weekly and several blood metabolic parameters levels were evaluated. Here, we present evidence that the offspring from mothers exposed to a HFD showed increased acetylation levels of histone 3 on lysine 9 (H3K9) in the liver at postnatal Day 1, whereas the levels of acetylation of H4K16, dimethylation of H3K27, and trimethylation of H3K9 showed no change. We also observed a higher perinatal weight and increased blood cholesterol levels when compared to the offspring on postnatal Day 1 born from CD-fed mothers. When mice born from obese mothers were fed with HFD, we observed that they gained more weight, presented higher blood cholesterol levels, and abdominal adipose tissue than mice born to the same mothers but fed with CD. Collectively, our results point toward maternal obesity and HFD consumption as a risk factor for epigenetic changes in the liver of the offspring, higher perinatal weight, increased weight gain, and altered blood cholesterol levels.

Update on Comparative Biology of Elephants: Factors Affecting Reproduction, Health and Welfare

Asian (Elephas maximus) and African (Loxodonta africana) elephants serve as important keystone, umbrella and flagship species. Despite that, population numbers are declining, due mainly to poaching and habitat destruction. Understanding reproductive mechanisms is vital to effective management, particularly insurance populations in captivity, and to that end, long-term biological databases are key to understanding how intrinsic and extrinsic factors affect reproductive function at individual and population levels. Through decades of hormonal and ultrasonographic monitoring, many unique aspects of zoo elephant reproduction have been identified, including differences in luteal steroidogenic activity, follicular maturation, pituitary gonadotropin secretion, fetal development and reproductive tract anatomy. Reproductive problems also hamper captive propagation efforts, particularly those related to abnormal or lack of ovarian cyclicity. Recent large-scale, multi-institutional studies and use of epidemiological approaches have identified factors important for good welfare and reproduction, which include enrichment, feeding diversity, good elephant-keeper relations, social compatibility, exercise, and not being obese. There are notable differences in reproductive mechanisms between Asian and African elephants, as well as the factors that influence reproduction and welfare, suggesting species-targeted management approaches are needed to maximize fitness. In the first edition, we discussed reproductive function in male and female elephants. Since then, a number of significant advances have been made primarily in female elephants, which will be the focus of this updated review.

The Effects of Overweight and Obesity on Assisted Reproduction Technology Outcomes

The aim of the present study was to assess the impact of professional nutrition assistance on assisted reproduction technology (ART) outcomes in overweight or obese patients with polycystic ovarian syndrome (PCOS). The study represents a retrospective analysis of fertilization rates, embryo quality and gestations after ART in seven PCOS patients, five obese and two overweight. The women attended a private Fertility Center in Brazil between the years 2010 and 2016. Out of the seven patients, the three that reached a successful gestation were the ones that underwent comprehensive lifestyle changes, taking care of their diet for a more prolonged period of time and reached an ideal weight loss during the nutrition counseling period.

Vitamin D and Obesity: Two Interacting Players in the Field of Infertility

Obesity plays an important role in human fertility in both genders. The same is true for vitamin D, for which accumulating evidence from observational human studies suggests a key role for both male and female fertility. In the latter case, however, robust data from relevant interventional studies are currently lacking. It is also not clear whether obesity and vitamin D deficiency, besides their independent effect on human infertility, act in synergy. Several pathogenetic mechanisms may be proposed as a linkage between vitamin D deficiency and obesity, with respect to infertility. In any case, the independent contribution of vitamin D deficiency in obese infertile states needs to be proven in interventional studies focusing on either vitamin D supplementation in obese or weight loss strategies in vitamin D-deficient infertile patients.