Potential Adverse Effects of Female and Male Obesity on Fertility: A Narrative Review

Self-assessed Physical and Mental Health and Fertility Expectations of Men and Women Across the Life Course

The fertility expectations of older women and men are becoming increasingly important for understanding fertility dynamics, given the increasing share of births after age 30. Because most health conditions deteriorate with age, understanding the relationship between health and fertility expectations is essential. We investigate whether changes in self-assessed general, physical, and mental health are linked to revised fertility expectations and how these associations vary over the life course. Drawing on a large longitudinal dataset for Australia, we demonstrate that across each health indicator, self-assessed poor health corresponds to lower fertility expectations and that a deterioration (or improvement) in self-assessed health coincides with a decrease (or increase) in men's and women's expectations of having a child. Individuals adapt their expectations more in response to physical health changes if they are older, and mental health conditions at younger ages appear relevant to men's fertility intentions. The results highlight that general, physical, and mental health are crucial drivers of changes in fertility plans, emphasizing the importance of integrating health considerations into future theoretical frameworks and empirical analyses of fertility.

Effects of pre-pregnancy BMI and gestational weight gain on pregnancy and neonatal outcomes in Poland

Overweight and obesity are significant public health concerns, affecting pregnant women and potentially leading to numerous complications for both maternal and neonatal health. The aim of this study is to estimate how pre-pregnancy overweight and obesity, as well as gestational weight gain, influence pregnancy outcomes and neonatal health in Poland. The study material consisted of data from 2878 women aged 16-46 years from hospitals in Warsaw and Krosno. The analysis included data on the course of singleton pregnancies and the biological condition of the newborns, correlated with pre-pregnancy Body Mass Index (BMI) and gestational weight gain (GWG), which were compared to the standards set by the Institute of Medicine (IOM). Factor that significantly influences pre-pregnancy BMI and GWG is the number of pregnancies. For first-born women pre-pregnancy BMI was significantly lower than that of women giving birth for the second, third and subsequent times (ANOVA p < 0.0001), at the same time, the increase in weight in this group was the greatest (ANOVA p < 0.0001). The study found that pre-pregnancy BMI correlates more strongly with the occurrence of gestational diabetes than GWG above IOM recommendations (regression: p < 0.0001, R = 0.112 vs. p < 0.0001, R = 0.104). Analogous correlations were observed for the incidence of gestational hypertension and termination of pregnancy by caesarean section. Birth weight and length are significantly affected by both pre-pregnancy BMI and GWG but the effect of weight change is stronger (birth weight - pre-pregnancy BMI regression p < 0.0001, R = 0.116; GWG p < 0.0001, R = 0.248; birth length - pre-pregnancy BMI regression p < 0.0001, R = 0.087; GWG p < 0.0001, R = 0.180). An analogous relationship was observed for the presence of macrosomia. For APGAR scores, an inverse relationship was observed; while GWG did not show a significant relationship with the first minute score, perinatal neonatal status was significantly related to the mother's pre-pregnancy BMI (regression p = 0.0006). Similarly, pre-pregnancy maternal BMI > 25 significantly increased the odds of perinatal injury and breastfeeding difficulties.

The relevance of female overweight in infertility treatment: a position statement of the Italian Society of Fertility and Sterility and Reproductive Medicine (SIFES-MR)

PURPOSE

Obesity is increasingly at the center of modern international healthcare systems. This is a position statement of the Italian Society of Fertility and Sterility and Reproductive Medicine (SIFES-MR) aimed at evaluating the impact of female overweight on infertility in order to improve fertility outcomes, including Assisted Reproductive technology (ART) treatments.

METHODS

The SIFES-MR writing group for this position statement was composed by Italian reproductive physicians, embryologists, and scientists with expertise in fertility evaluation, assisted reproduction technologies, and laboratory quality management. The positions stated are based on consensus by the authors, who met over a six-month period. The consensus emerged after thorough review of pertinent literature and standards concerning the impact of female overweight, complemented by extensive dialogue and discussion among the authors. Additionally, input from society members was considered, leading to revisions and eventual approval by the SIFES-MR governing council.

RESULTS

An increasing number of women affected by overweight and infertility accessing to ART treatments are expected in the future. A comprehensive counseling since the first access to infertility care is mandatory and should promote weight restoration, with the aim to improve the likelihood of spontaneous unassisted conception. Careful preconceptional evaluation of obese women is strongly encouraged for counseling purpose and comorbidities should be corrected by a multidisciplinary approach before spontaneous or medically assisted conception. Indeed, female obesity is responsible for high-risk pregnancies, with potential consequences in infants and during childhood. When in vitro fertilization is indicated, the risk of venous thromboembolism exacerbated by controlled ovarian stimulation should be assessed.

CONCLUSIONS

Before IVF, different therapeutic approaches and expectant management to reduce overweight could be offered, and the age-related algorithm herein proposed by SIFES may represent an interesting tool for a better personalization of infertility care in these women. The treatment of infertility cannot ignore the correct management of female overweight, given the serious consequences that this condition can have on the outcomes of pregnancies and future generations. IVF specialists should tailor access and modalities of IVF treatment to this class of high-risk women.

Correlation between uterine microbiota and pregnancy outcomes of embryo transfer in overweight and obese women

Objective

Currently, it has been reported that uterine microbiota affected pregnancy outcomes in assisted reproductive technology, but little was known in obese women. Thus, this study aims to explore how body weight affects pregnancy outcomes by comparing the differences in uterine microbiota between women of normal weight and those with obesity or overweight.

Methods

The study included 45 embryo transfer cycles. Patients were divided into two groups based on body mass index (BMI): normal-weight group, BMI ≤23.9 kg/m² (Con group, n=31) and obesity/overweight group, BMI >23.9 kg/m² (OwOb group, n=14). Microbial samples were collected from the catheter tips and analyzed using RNA Ribosomal 16S.

Results

In 45 women, the β-human chorionic gonadotropin (β-hCG) positivity rate and clinical pregnancy rate 10-12 days after embryo transfer were higher in the Con group. At the genus level, the relative abundance of Lactobacillus in the Con group was 2.2 times higher than that in the OwOb group. The Alpha diversity in the OwOb group was significantly higher than in the Con group (p=0.028). After regrouping based on β-hCG results 10-12 days post-transfer, in the Con-negative group (the group with negative β-hCG in the Con group, n=16) the relative abundances of pathogenic bacteria such as Klebsiella (p<0.001), Parasutterella (p=0.004), Dialister (p=0.01), and Gardnerella (p=0.029) were significantly higher than in the Con-positive group (the group with positive β-hCG in the Con group, n=15).

Conclusion

Overweight and obese women possess a distinct uterine microbiota, characterized by a lower relative abundance of Lactobacillus and an increased relative abundance of pathogenic bacteria, along with specific genera strongly associated with obesity. In individuals with higher BMI, pathogenic bacteria are more likely to impair endometrial receptivity, ultimately leading to adverse pregnancy outcomes. Therefore, modulating the uterine microbiota in overweight/obese women may improve assisted reproductive technology success rates.

Medical therapy to treat obesity and optimize fertility in women of reproductive age: a narrative review

BACKGROUND

Overweight and obesity-chronic illnesses in which an increase in body fat promotes adipose tissue dysfunction and abnormal fat mass resulting in adverse metabolic, biomechanical, and psychosocial health consequences-negatively impact female fertility. Adverse conception outcomes are multifactorial, ranging from poor oocyte quality and implantation issues to miscarriages and fetal health issues. However, with the advent of novel pharmacologic agents, significant weight loss can be achieved, improving the chances of healthy pregnancies, and their use should be considered during periconceptual counseling. There are currently 6 FDA-approved medications for weight loss: 2 GLP1-receptor agonists (GLP1-RAs) liraglutide and semaglutide, 1 dual GLP-1 and gastric inhibitory peptide agonist (GLP1-GIP) tirzepatide, Contrave (naltrexone/bupropion), Qsymia (phentermine/Topamax), and Xenical (orlistat). GLP1-RAs reduce food cravings, appetite, and "food noise" and improve insulin sensitivity and satiety, all of which lead to significant weight loss, ranging from 6 to 30% of starting total body weight or greater, depending on the specific agent used. Their efficacy and relative safety should make them first-line options for women seeking to lose weight in the year before trying to conceive. Contrave, the combination of naltrexone and bupropion, seems to work most significantly for weight loss by inhibiting the rewarding and reinforcing effects of food consumption. Clinical trials report ~ 6% loss of starting total body weight with use of Contrave, as well as improvement in metabolic health factors. It may also improve a woman's ability to conceive by mitigating the effects of PCOS and endometriosis and reducing the drive for alcohol and smoking. Qsymia, the combination of phentermine and topiramate, results in more weight loss than Contrave but cannot be used in the acute preconception period, as its topiramate component is a known teratogen. Orlistat is another FDA-approved medication for weight loss; however, it is currently used much less often than other anti-obesity drugs because of its relatively lower efficacy and significant side effects. Bariatric surgery, which can lead to significant weight loss (25-50%), was previously regarded as the most durable method for weight loss, before the advent of GLP1-RAs. Given the inherent risks of surgery, the development of vitamin (i.e. B12, folate, vitamin D) and mineral (i.e. iron, copper, zinc) deficiencies, that may impact the health of the mother and fetus, as well as the recommended delay of 1-2 years prior to attempting pregnancy, bariatric surgery should not be considered first-line therapy for obesity management in women of reproductive age, especially for women who are hoping to conceive quickly or are nearing advanced maternal age.

CONCLUSION

Clinically significant and meaningful weight loss is achievable with pharmacotherapy to help enhance fertility in women of reproductive age who are overweight or obese. Current research supports the use of weight loss medications for enhancing spontaneous conception and response to ovulation induction. Further research on the effects upon live birth rates are warranted. For meaningful weight loss, GLP1-RAs can be considered for use in the preconception period, as long as they are stopped at least 2 months before conception. Contrave can be considered as well, though resulting in less weight loss. Phentermine and Qsymia are teratogenic but can be used with contraception for weight loss before trying to get pregnant.

The Contribution of Precision Nutrition Intervention in Subfertile Couples

BACKGROUND/AIM

Subfertility is characterized by a decrease in reproductive efficiency, which can result in delayed pregnancy, and affects one in six individuals during their lifetime. The present narrative review aims to evaluate the contribution of precision nutrition to changes in fertility in subfertile couples.

METHODS

The literature review was carried out through bibliographic research in the PubMed, Scopus, SciELO and Google Scholar databases. The following search criteria were applied: (1) original articles and narrative, systematic or meta-analytic reviews, and (2) the individual or combined use of the following keywords: "genetic variation", "nutrigenetics", "precision nutrition", "couple's subfertility", and "couple's infertility". A preliminary reading of all the articles was carried out, and only those that best fit the themes and subthemes of the narrative review were selected.

RESULTS

Scientific evidence suggests that adherence to a healthy diet that follows the Mediterranean pattern is associated with increased fertility in women and improved semen quality in men, better metabolic health and reduced levels of inflammation and oxidative stress, as well as maintaining a healthy body weight. The integration of different tools, such as nutrigenetics, predictive biochemical analyses, intestinal microbiota tests and clinical nutrition software, used in precision nutrition interventions can contribute to providing information on how diet and genetics interact and how they can influence fertility.

CONCLUSIONS

The adoption of a multidisciplinary and precision approach allows the design of dietary and lifestyle recommendations adapted to the specific characteristics and needs of couples with subfertility, thus optimizing reproductive health outcomes and achieving successful conception.

Young adult's views on using a poster to learn about fertility: redesigning the fertility education poster

Fertility awareness should be taught to everyone. The International Reproductive Health Education Collaboration (IRHEC) designed a fertility poster in 2019 but did not have a specific target group in mind. Studies have been conducted in Denmark and Sweden to determine how the poster can be redesigned. In this study, we carried out focus groups with young adults in the UK to ask their views of the poster, with the aim of redesigning it. Six focus groups were undertaken with twenty seven, 18-25 year olds. Five questions were asked: 1. What are your thoughts, feelings, and reactions to the poster? 2. Did you learn anything from the poster? 3. How has reading the poster impacted your opinions or thoughts about having children? 4. What are your opinions about using a poster format to inform and start reflections regarding family building? 5. Reading through each point are there any changes to be made? Content analysis was performed. Themes identified revealed the information on the poster gave the participants some anxiety and apprehension, especially regarding the effect of age on fertility, perceptions of IVF, and gaps in knowledge. The fertility education poster is a good resource for education, but other resources should be developed.

Artificial Intelligence in Human Reproduction

The use of artificial intelligence (AI) in human reproduction is a rapidly evolving field with both exciting possibilities and ethical considerations. This technology has the potential to improve success rates and reduce the emotional and financial burden of infertility. However, it also raises ethical and privacy concerns. This paper presents an overview of the current and potential applications of AI in human reproduction. It explores the use of AI in various aspects of reproductive medicine, including fertility tracking, assisted reproductive technologies, management of pregnancy complications, and laboratory automation. In addition, we discuss the need for robust ethical frameworks and regulations to ensure the responsible and equitable use of AI in reproductive medicine.

Impact of bariatric surgery on infertility in obese women: a systematic review and meta-analysis

Background

The prevalence of obesity is increasing worldwide, with several consequences, including reduced fertility in both men and women. One of the ways to reduce weight is bariatric surgery. The aim of this systematic review and meta-analysis study was to evaluate the effectiveness of bariatric surgery on weight loss and subsequent improvement of fertility in obese infertile women.

Methods

Several databases were searched using MESH terms to investigate the studies that evaluated the fertility rates after bariatric surgery in infertile obese women. Related data were obtained and analyzed using Stata software with a P-value ≤0.05, which was considered as significant.

Results

Of the 283 articles related to the purpose of this study, 9 articles, including 231 obese infertile women, were included in the study. BMI before surgery was 42.2 [95% CI= 39.2-45.2] and BMI after surgery was 31.9 (95% CI= 28.9-34.8), which shows the significance of weight loss after bariatric surgery. Conception rate after bariatric surgery weight loss was increased and was 67% (95% CI= 47-87%, P-value <0.05).

Conclusions

Bariatric surgery had a significant effect on the reduction of BMI and subsequent significant improvement of fertility in obese infertile women.

Efficacy of intrauterine autologous blood cell derivatives in enhancing endometrial thickness and IVF outcomes for women with recurrent implantation failure: a retrospective cohort study

PURPOSE

The purpose of this study was to determine the effects of intrauterine infusion of autologous blood cell derivative (ABCD) on endometrial thickness and pregnancy outcomes in a group of patients who underwent IVF with recurrent implantation failure (RIF) and who had either a normal endometrium or thin endometrium.

METHODS

This retrospective study included 63 patients who experienced RIF at the Department of Reproductive Medicine and Surgery, KMC, Manipal, between January 2021 and March 2024 and who received three doses of intrauterine ABCD infusion to prepare the endometrium for frozen embryo transfer (FET).

RESULTS

We enrolled 63 RIF patients, 30 with a normal endometrium (NEM) and 33 with a thin endometrium (TEM). The endometrial thickness (EMT) significantly increased across all the groups. After 3 cycles of intrauterine ABCD infusion, the mean increases in EMT in the NEM and TEM groups were 0.77 mm and 1.36 mm, respectively, which were statistically significant. Among the 62 completed FET cycles, 40.3% were positive for beta-hCG. The clinical pregnancy rate was 33.8% (40% in the NEM group, 28.1% in the TEM group), and the live birth rate was 24.2% (30% in the NEM group, 18.8% in the TEM group). A total of 9.7% of pregnancies had spontaneous miscarriages. Moreover, the EMT did not differ between the pregnant and nonpregnant groups.

CONCLUSION

Intrauterine ABCD infusion improves the pregnancy outcomes of patients with RIF, regardless of the EMT. The results of this study revealed that endometrial receptivity improved significantly along with the EMT.

Preconception and Early-Pregnancy Body Mass Index in Women and Men, Time to Pregnancy, and Risk of Miscarriage

Importance

Obesity in women is associated with reduced fertility and an increased risk of miscarriage. These associations might also be present across the full range of body mass index (BMI) categories as well as among men.

Objective

To investigate the associations of preconception BMI in both partners with time to pregnancy and miscarriage.

Design, Setting, and Participants

This population-based prospective cohort study was conducted in Rotterdam, the Netherlands, between August 9, 2017, and July 1, 2021. A total of 3604 women and their partners were included from the preconception period onward with follow-up until birth. The date of analysis was July 12, 2024.

Exposure

Body mass index (calculated as weight in kilograms divided by height in meters squared) measured in preconception or early pregnancy.

Main Outcome and Measures

Fecundability, defined as the probability of conceiving within 1 month; subfertility, defined as time to pregnancy or duration of actively pursuing pregnancy of more than 12 months or use of assisted reproductive technology; and miscarriage, defined as pregnancy loss before 22 weeks of gestation. These measures were assessed using questionnaires and via the obstetric caregiver.

Results

The study population for time-to-pregnancy analyses consisted of 3033 episodes among women (median age, 31.6 years [IQR, 29.2-34.5 years]; median BMI, 23.5 [IQR, 21.2-26.5]) and 2288 episodes among men (median age, 33.4 years [IQR, 30.5-36.8 years]; median BMI, 24.9 [IQR, 23.0-27.4]). The study population for miscarriage analyses consisted of 2770 pregnancy episodes among women (median age, 31.5 years [IQR, 28.9-34.3 years]; median BMI, 23.5 [IQR, 21.3-26.7]) and 2189 pregnancy episodes among men (median age, 33.5 years [IQR, 30.4-36.8 years]; median BMI, 25.0 [IQR, 23.0-27.5]). Higher BMI in women and men was associated with lower fecundability: for every unit increase in BMI, fecundability decreased (fecundability ratio [FR]: women, 0.98 [95% CI, 0.97-0.99]; men, 0.99 [95% CI, 0.98-1.00]). Women with overweight (FR, 0.88 [95% CI, 0.80-0.98]) and obesity (FR, 0.72 [95% CI, 0.63-0.82]) had lower fecundability compared with women with normal weight. Compared with normal weight in women, underweight (odds ratio [OR], 1.88 [95% CI, 1.22-2.88]), overweight (OR, 1.35 [95% CI, 1.11-1.63]), and obesity (OR, 1.67 [95% CI, 1.30-2.13]) were associated with increased odds of subfertility. In men, obesity was associated with increased odds of subfertility (OR, 1.69 [95% CI, 1.24-2.31]). Compared with normal weight in women, overweight (OR, 1.49 [95% CI, 1.12-1.98]) and obesity (OR, 1.44 [95% CI, 1.00-2.08]) were associated with increased odds of miscarriage.

Conclusions and Relevance

In this cohort study, BMI outside of the normal category in women and men during the preconception or early-pregnancy periods was associated with time to pregnancy and miscarriage. Optimizing BMI in women and men from the preconception period onward might be an important strategy to improve fertility outcomes.

Genes linked to obesity-related infertility: bridging the knowledge gap

Genetic factors play a pivotal role in the complex relationship between obesity and infertility. This article delves into the genetics of obesity-related infertility, focusing on the essential genes and mechanisms in both sexes. We explored infertility factors in obese females, focusing on polycystic ovary syndrome (PCOS) and the influence of genes like insulin receptor (INSR), androgen receptor (AR), and follicle-stimulating hormone receptor (FSHR). Epigenetic changes are believed to contribute to PCOS-related infertility. The impact of adipokines and inflammation on obesity-related infertility has been discussed, with genes such as fat mass and obesity (FTO) and melanocortin-4-receptor (MC4R) playing significant roles. Genetic factors affecting sperm quality and function, including nuclear receptor subfamily 3 group C member 1 (NR3C1) and methylenetetrahydrofolate reductase (MTHFR), have been investigated in obesity-related infertility in males. Hormonal dysregulation influenced by genetic markers, such as leptin receptor (LEPR), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6), was also examined. Genetic factors play a vital role in obesity-related infertility in both sexes. Genes involved in metabolism, hormonal regulation, and inflammation contribute to the complex association between obesity and infertility. Epigenetic changes further complicate the relationship. Understanding these genetic mechanisms is essential to address obesity-related infertility and develop personalized interventions.

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.

Pathophysiology of obesity-related infertility and its prevention and treatment by potential phytotherapeutics

BACKGROUND

Obesity is a complex multifactorial disease in which the accumulation of excess body fat has adverse health effects, as it can increase the risk of several problems, including infertility, in both men and women. Obesity and infertility have risen together in recent years. Against this background, the present review aims to highlight the impact of obesity on infertility and the underlying pathophysiology of obesity-related infertility (ORI) in men and women, and to provide readers with knowledge of current trends in the effective development of phytotherapeutics for its treatment.

METHODS

We thoroughly searched in PubMed, MEDLINE, Scopus, EMBASE, and Google Scholar to find all relevant papers on ORI and the therapeutic effects of phytotherapeutics on ORI in men and women.

RESULTS

The extensive search of the available literature revealed that obesity affects reproductive function through several complex mechanisms such as hyperlipidaemia, hyperinsulinaemia, hyperandrogenism, increased body mass index, disruption of the hormonal milieu, systemic inflammation, oxidative stress, alterations in epigenetics and dysbiosis. On the other hand, several studies reported that phytotherapeutics has a broad therapeutic spectrum of action by improving sex hormone homeostasis, ovarian dysfunction, menstrual cycle and inhibiting ovarian hyperplasia, as well as down-regulating ovarian apoptosis, inflammation and oxidative stress, and controlling metabolic dysfunction in obese women. Male infertility is also addressed by phytotherapeutics by suppressing lipogenesis, increasing testosterone, 3β-HSD and 17β-HSD levels, improving sperm parameters and attenuating testicular dyslipidaemia, oxidative stress, inflammation and germ cell apoptosis.

CONCLUSIONS

In the present review, we discussed the effects of obesity on reproductive dysfunction in men and women and the underlying pathophysiology of ORI. In addition, the therapeutic effect of phytotherapeutics against ORI was highlighted.

Intra-patient analysis of individual weight gain or loss between IVF cycles: cycle now and transfer later

STUDY QUESTION

What is the impact of clinically significant weight change on outcomes related to IVF cycle performance?

SUMMARY ANSWER

While individual weight loss did not significantly impact ovarian response to stimulation or other cycle outcome parameters in our study, some positive associations were found for individual weight gain.

WHAT IS KNOWN ALREADY

The role of weight-change in patients undergoing IVF has been largely studied by comparing weight loss in different cohorts of patients stratified by a static BMI. Specifically, obesity has been extensively studied in relation to its negative effects on assisted or unassisted conception outcomes and ovulatory function. Previous research has shown conflicting results, while BMI, which is commonly used as a marker of obesity, may not accurately reflect the underlying factors affecting fertility in obese patients.

STUDY DESIGN, SIZE, DURATION

This study utilized a retrospective within-patient repeated measurement analysis design to assess the impact of weight change on IVF outcomes in cycles where all embryos were cryopreserved at the blastocyst stage for transfer at a later date.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study was conducted at an academically affiliated fertility center. The data included 961 women who underwent at least two IVF cycles between December 2014 and June 2020, with documented short-term weight gain (n = 607) or weight loss (n = 354) within 1 year from their initial IVF cycle. Multivariable generalized estimating equations (GEE) and generalized linear mixed models (GLMM) were employed to assess associations between weight change and outcomes across cycles.

MAIN RESULTS AND THE ROLE OF CHANCE

The multivariable models indicated that weight loss did not show any significant associations with the numbers of oocytes retrieved, or mature oocytes, the fertilization rate or the blastulation rate. However, weight gain demonstrated a minor positive association with the number of oocytes retrieved in both GEE models (coefficient: 0.01, 95% CI: 0.00-0.01) and GLMM models (0.01, 95% CI: 0.01-0.00). There was also a potential increase in the fertilization rate with weight gain, as indicated by a positive coefficient in both GEE models (coefficient: 0.01, 95% CI: 0.00-0.02) and GLMM models (coefficient: 0.01, 95% CI: 0.00-0.01). However, the association between weight gain and the embryo blastulation rate was not statistically significant in any model.

LIMITATIONS, REASONS FOR CAUTION

This study focused on cycle performance parameters instead of reproductive outcomes, which restricted our ability to evaluate the impact of weight change on cumulative live birth rates. Additionally, the study did not account for variables such as stimulation protocols, potentially introducing confounding factors and limiting the generalizability of the results.

WIDER IMPLICATIONS OF THE FINDINGS

Although obesity is associated with adverse obstetrical risks, there is less evidence of adverse reproductive outcomes in IVF cycles. We therefore recommend that an IVF cycle should not be delayed due to weight, so that the patient is not adversely affected by increasing age. The IVF cycle should aim to freeze all embryos, so that embryo transfer can then occur after weight loss, so as to limit the recognized obstetrical risks.

STUDY FUNDING/COMPETING INTEREST(S)

The study was not funded and there were no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Testicular fat deposition attenuates reproductive performance via decreased follicle-stimulating hormone level and sperm meiosis and testosterone synthesis in mouse

OBJECTIVE

Testicular fat deposition has been reported to affect animal reproduction. However, the underlying mechanism remains poorly understood. The present study explored whether sperm meiosis and testosterone synthesis contribute to mouse testicular fat depositioninduced reproductive performance.

METHODS

High fat diet (HFD)-induced obesity CD1 mice (DIO) were used as a testicular fat deposition model. The serum hormone test was performed by agent kit. The quality of sperm was assessed using a Sperm Class Analyzer. Testicular tissue morphology was analyzed by histochemical methods. The expression of spermatocyte marker molecules was monitored by an immuno-fluorescence microscope during meiosis. Analysis of the synthesis of testosterone was performed by real-time polymerase chain reaction and reagent kit.

RESULTS

It was found that there was a significant increase in body weight among DIO mice, however, the food intake showed no difference compared to control mice fed a normal diet (CTR). The number of offspring in DIO mice decreased, but there was no significant difference from the CTR group. The levels of follicle-stimulating hormone were lower in DIO mice and their luteinizing hormone levels were similar. The results showed a remarkable decrease in sperm density and motility among DIO mice. We also found that fat accumulation affected the meiosis process, mainly reflected in the cross-exchange of homologous chromosomes. In addition, overweight increased fat deposition in the testis and reduced the expression of testosterone synthesis-related enzymes, thereby affecting the synthesis and secretion of testosterone by testicular Leydig cells.

CONCLUSION

Fat accumulation in the testes causes testicular cell dysfunction, which affects testosterone hormone synthesis and ultimately affects sperm formation.

Impact of GLP-1 Agonists on Male Reproductive Health-A Narrative Review

Background and objective-Obesity is a prevalent health concern that notably impairs male fertility through hormonal disruptions and other pathophysiological alterations. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) can significantly reduce weight. This narrative review synthesizes the existing literature discussing the impact of glucagon-like peptide-GLP-1 RAs on the male reproductive system, particularly on the hypothalamic-pituitary-gonadal axis and spermatogenesis, highlighting their potential impact on male fertility. Material and methods-PubMed database was used for the retrieval of English-language articles published up to November 2023. This non-systematic literature review predominantly concentrates on both pre-clinical and clinical studies pertaining to GLP-1 RAs, specifically exploring their impact on male reproductive hormones and sperm parameters. Results-GLP-1 receptors have been identified within the male reproductive system according to the existing literature. While the exact mechanisms are not well understood, they appear to be involved in glucose homeostasis and energy metabolism, both vital processes in spermatogenesis. Multiple clinical trials have demonstrated the efficacy of GLP-1 RAs for promoting weight loss. Recent studies show that the use of GLP-1 RAs in obese males may enhance sperm metabolism, motility, and insulin secretion in vitro, along with positive effects on the human Sertoli cells. Recent clinical trials discussed in this review demonstrate weight loss associated with GLP-1 RAs is correlated with improvements in sperm count, concentration, and motility. However, the direct impact of GLP-1 RAs on male reproductive hormones remains unclear, necessitating further research to confirm their potential role in treating male infertility. Conclusions-This narrative review summarizes the existing literature discussing the potential impact of GLP-1 RA on the male reproductive system, emphasizing their potential therapeutic role in addressing idiopathic infertility in obese men. Despite numerous studies exploring the influence of GLP-1 and GLP-1 RAs on reproductive hormones, testicular function, and spermatogenesis, further clinical trials are crucial to validate initial evidence. Longer follow-up periods are essential to address uncertainties regarding the long-term repercussions and outcomes of GLP-1 RA use. While this holds true, the current literature suggests that GLP-1RAs show promise as a potential therapeutic approach for improving sperm parameters in obese men.

Comprehensive Review of Anesthetic Evaluation and Management in Obese Female Patients Undergoing In Vitro Fertilization

Obesity has become a global health epidemic with profound implications for various medical specialties, including reproductive medicine. This comprehensive review focuses on the anesthetic evaluation and management of obese patients undergoing in vitro fertilization (IVF) procedures. Obesity, as defined by BMI, is associated with infertility and poses unique challenges for anesthetic care. The review also addresses the timing of anesthesia concerning IVF procedures, the impact of obesity on IVF success rates, and the importance of emotional and psychological support for obese patients undergoing IVF. Challenges and future directions in the field are highlighted, focusing on ongoing research, emerging technologies, and the role of multidisciplinary teams in managing these complex cases. In conclusion, this review underscores the critical role of tailored anesthesia and perioperative care in optimizing outcomes for obese patients undergoing IVF. It provides valuable insights for anesthetic providers, reproductive specialists, and healthcare teams, emphasizing the need for a patient-centered approach to address the unique challenges posed by obesity in the context of assisted reproductive technology.

Establishing the relationships between adiposity and reproductive factors: a multivariable Mendelian randomization analysis

BACKGROUND

Few studies have investigated associations between adiposity and reproductive factors using causal methods, both of which have a number of consequences on women's health. Here we assess whether adiposity at different points in the lifecourse affects reproductive factors differently and independently, and the plausibility of the impact of reproductive factors on adiposity.

METHODS

We used genetic data from UK Biobank (273,238 women) and other consortia (EGG, GIANT, ReproGen and SSGAC) for eight reproductive factors: age at menarche, age at menopause, age at first birth, age at last birth, number of births, being parous, age first had sexual intercourse and lifetime number of sexual partners, and two adiposity traits: childhood and adulthood body size. We applied multivariable Mendelian randomization to account for genetic correlation and to estimate the causal effects of childhood and adulthood adiposity, independently of each other, on reproductive factors. Additionally, we estimated the effects of reproductive factors, independently of other relevant reproductive factors, on adulthood adiposity.

RESULTS

We found a higher childhood body size leads to an earlier age at menarche, and an earlier age at menarche leads to a higher adulthood body size. Furthermore, we find contrasting and independent effects of childhood and adulthood body size on age at first birth (beta 0.22 SD (95% confidence interval: 0.14, 0.31) vs - 2.49 (- 2.93, - 2.06) per 1 SD increase), age at last birth (0.13 (0.06,0.21) vs - 1.86 (- 2.23, - 1.48) per 1 SD increase), age at menopause (0.17 (0.09, 0.25) vs - 0.99 (- 1.39, - 0.59) per 1 SD increase), and likelihood of having children (Odds ratio 0.97 (0.95, 1.00) vs 1.20 (1.06, 1.37) per 1 SD increase).

CONCLUSIONS

Our findings demonstrate the importance of considering a lifecourse approach when investigating the inter-relationships between adiposity measures and reproductive events, as well as the use of 'age specific' genetic instruments when evaluating lifecourse hypotheses in a Mendelian randomization framework.

Patient perceptions of body mass index restrictions limiting fertility care for women with high body mass index

RESEARCH QUESTION

What is the patient experience of women with high body mass index (BMI) with BMI restrictions that limit fertility care?

DESIGN

Qualitative study using in-depth, semi-structured interview methodology. Interview transcripts were analysed for iterative themes in accordance with principles of grounded theory.

RESULTS

Forty women with a BMI of 35 kg/m2 or higher with scheduled or completed appointment at the Reproductive Endocrinology and Infertility (REI) clinic completed an interview. Most participants experienced BMI restrictions as unjust. Many perceived that BMI restrictions on fertility care may be medically justified and were in support of weight loss discussions to improve chances of pregnancy; however, several argued that they should have autonomy to commence treatment following an individualized risk assessment. Participants offered recommendations to improve discussion of BMI restrictions and weight loss, including framing the conversation as supportive of their reproductive goals and offering proactive referral to weight loss support to prevent the perception that BMI is a categorical exclusion to future fertility care.

CONCLUSIONS

Participant experiences highlight a need for enhanced strategies for communicating BMI restrictions and weight loss recommendations in ways that are perceived to be supportive of patients' fertility goals without further contributing to weight bias and stigma experienced in medical settings. Opportunities for training to mitigate experiences of weight stigma may be beneficial for clinical and non-clinical staff. Evaluation of BMI policies should be undertaken within the context of clinic policies that permit or prohibit fertility care for other high-risk groups.

Vaginal microbiome in obesity and its impact on reproduction

A number of reproductive outcomes have been increasingly found to be affected by the vaginal microbiota. Obesity has become a global epidemic, affecting increasing numbers of reproductive-age women, and has been shown to be a risk factor for a number of adverse female health outcomes. A healthy vaginal microbiome is characterized by Lactobacillus-dominance, in particular Lactobacillus crispatus; obesity has been found to be associated with higher diversity and a lower likelihood of Lactobacillus-dominance. In this review, we summarize the evidence on the vaginal microbiome in obese women and the impact on reproductive outcomes such as conception rates, early pregnancy, and preterm birth. We further explore the mechanisms by which obesity may result in an altered microbial composition and highlight future avenues for therapeutic targeting of the vaginal microbiota.

The role of apelinergic system in metabolism and reproductive system in normal and pathological conditions: an overview

Lifestyle changes have made metabolic disorders as one of the major threats to life. Growing evidence demonstrates that obesity and diabetes disrupt the reproductive system by affecting the gonads and the hypothalamus-pituitary-gonadal (HPG) axis. Apelin, an adipocytokine, and its receptor (APJ) are broadly expressed in the hypothalamus nuclei, such as paraventricular and supraoptic, where gonadotropin-releasing hormone (GnRH) is released, and all three lobes of the pituitary, indicating that apelin is involved in the control of reproductive function. Moreover, apelin affects food intake, insulin sensitivity, fluid homeostasis, and glucose and lipid metabolisms. This review outlined the physiological effects of the apelinergic system, the relationship between apelin and metabolic disorders such as diabetes and obesity, as well as the effect of apelin on the reproductive system in both gender. The apelin-APJ system can be considered a potential therapeutic target in the management of obesity-associated metabolic dysfunction and reproductive disorders.

The relationship of reproductive factors with adiposity and body shape indices changes overtime: findings from a community-based study

BACKGROUND

Studies focusing on the relationships of adiposity and body shape indices with reproductive factors have reported conflicting results. This study aimed to investigate the influence of reproductive factors on adiposity and body shape indices changes overtime.

MATERIALS AND METHODS

In this community-based prospective study, 1636 postmenopausal women were selected from Tehran Lipid and Glucose Study (TLGS). The unadjusted and adjusted Generalized Estimating Equation models (GEE) were applied to investigate secular longitudinal trends of adiposity and body shape indices.

RESULTS

According to the adjusted GEE models, mean changes in body mass index (BMI) in women with early menarche was 1.18 kg/m² higher than those with normal menarche age (P = 0.030). Moreover, the mean changes in BMI overtime were 0.11 kg/m² higher in women with premature/early menopausal age than those with normal menopausal age (P = 0.012). Mean changes of waist circumference (WC) in women with late menopause were 2.27 cm higher than those with normal menopausal age (P = 0.036). We also observed higher mean changes in a body shape index (ABSI) in women with late menopause (P = 0.037), compared to those with normal menopausal age. We found a marginal effect of parity on BMI and WC as well.

CONCLUSIONS

This study demonstrated higher BMI in females with earlier menarche age. We also showed higher values of BMI overtime in women with premature/ early menopause, whereas women with late menopausal age had higher WC and ABSI values. However, more longitudinal studies investigating body composition indices by adjusting all potential confounders are still required to confirm our study findings.

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.

The challenges of obesity for fertility: A FIGO literature review

Obesity has been linked to infertility through several mechanisms, including at a molecular level. Those living with obesity face additional barriers to accessing fertility treatments and achieving a successful pregnancy, which can contribute to their economic and psychosocial stressors. There is scope to further improve care for people living with obesity and infertility with empathy, via a multidisciplinary approach.

The impact of body mass index on laboratory, clinical outcomes and treatment costs in assisted reproduction: a retrospective cohort study

BACKGROUND

The aim of this study was to evaluate the influence of the body mass index (BMI) on laboratory, clinical outcomes and treatment costs of assisted reproduction, as there are still controversial and inconclusive studies on this subject.

METHODS

This research was retrospective cohort study, including women undergoing assisted reproduction in a Reproductive Medicine Center between 2013 and 2020. The participants were divided into groups according to BMI (kg/m2): Group 1 < 25; Group 2, 25-29.9 and Group 3, ≥ 30. A total of 1753 in vitro fertilization (IVF) fresh embryo transfer (ET) cycles were included for assisted reproduction outcomes analysis and 1869 IVF-ET plus frozen embryo transfer (FET) for cumulative pregnancy analysis.

RESULTS

As higher the BMI, higher was the proportion of canceled IVF cycles (G1 (6.9%) vs. G2 (7.8%) vs. G3 (10.4%), p = 0.002) and gonadotropin's total dose (IU) and treatment costs (G1 (1685 ± 595, U$ 683,02) vs. G2 (1779 ± 610, U$ 721,13) vs. G3 (1805 ± 563, U$ 764,09), p = 0.001). A greater number of mature oocytes was observed in G1 and G2 (6 [6.4-7.0] vs. 6 [5.6-6.6] vs. 4 [4.6-6.7], p = 0.011), which was not found in oocyte maturity rate (p = 0.877). A significant linear tendency (p = 0.042) was found in cumulative pregnancy rates, pointing to worse clinical outcomes in overweight and obese patients.

CONCLUSION

These findings highlight the importance of considering the higher treatment costs for these patients, beyond all the well-known risks regarding weight excess, fertility, and pregnancy, before starting IVF treatments.

Clinical management of pregnancy in women with polycystic ovary syndrome: An expert opinion

Polycystic ovary syndrome (PCOS) is associated with a higher risk for pregnancy and birth complications according to the specific features associated with PCOS. The features include obesity before and during pregnancy, hyperandrogenism, insulin resistance, infertility, cardiometabolic risk factors, and poor mental health. PCOS is not often recognized as a risk factor for poor pregnancy and birth outcomes in pregnancy care guidelines, while its associated features are. Pregnancy-related risk profile should ideally be assessed for modifiable risk factors (e.g., lifestyle and weight management) at preconception in women with PCOS. Hyperglycaemia should be screened using a 75-g oral glucose tolerance test at preconception or within the first 20 weeks of pregnancy if it has not been performed at preconception and should be repeated at 24-28 weeks of pregnancy. In the absence of evidence of benefit for strategies specific to women with PCOS, the international evidence-based guidelines for the assessment and management of PCOS recommend screening, optimizing, and monitoring risk profile in women with PCOS (at preconception, during and postpregnancy) consistent with the recommendations for the general population. Recommended factors include blood glucose, weight, blood pressure, smoking, alcohol, diet, exercise, sleep and mental health, emotional, and sexual health among women with PCOS. The guidelines recommend Metformin in addition to lifestyle for assisting with weight management and improving cardiometabolic risk factors, particularly in those with overweight or obesity. Letrozole is considered the first-line pharmacological treatment for anovulatory infertility in PCOS. Individualized approach should be considered in the management of pregnancy in PCOS.

Human fertility and sleep disturbances: A narrative review

INTRODUCTION

Many factors may be hidden behind the global fertility decline observed in Western countries. Alongside the progressively increased age of infertile couples, environmental and behavioural factors, including non-optimal lifestyle habits, should be considered. Among these, sleep disorders have been suggested to be linked to human fertility.

METHODS

This is a narrative review, describing first sleep physiology, its disturbances, and the tools able to quantify sleep dysfunction. Then, we consider all available studies aimed at investigating the connection between sleep disorders and human fertility, providing a comprehensive view on this topic.

RESULTS

Forty-two studies investigating the relationship between sleep habits and human reproduction were included. All the published evidence was grouped according to the aspect of human fertility considered, i.e. i) female reproductive functions, ii) male reproductive functions, iii) natural conception and iv) assisted reproduction. For each of the sub-groups considered, the connection between sleep dysregulation and human fertility was classified according to specific sleep characteristics, such as sleep duration, quality, and habits. In addition, possible physio-pathological mechanisms proposed to support the link between sleep and fertility were summarized.

CONCLUSION

This review summarizes the most relevant findings about the intricate and still largely unknown network of molecular pathways involved in the regulation of circadian homeostasis, to which sleep contributes, essential for reproductive physiology. Thus, many mechanisms seem correlate sleep disorders to reproductive health, such as adrenal activation, circadian dysregulation, and genetic influences. This review highlights the need to properly designed trials on the topic.

Association between metabolic disorders and seminal plasma miRNA levels: a pilot study

BACKGROUND

Excess weight and metabolic disorders have a negative impact on male reproductive functions. The mechanisms involved are numerous and complex and epigenetic mechanisms may also be involved, notably through the small non-coding RNAs. Among them, microRNAs (miRNAs) are of particular interest. This preliminary study aimed to identify the miRNAs differentially enriched in seminal plasma related to metabolic disorders and if some are also associated with spermatic parameters alterations. One hundred and sixty men between 18 to 45 years, partners of infertile couple, were included in this cohort. The miRNAs associated with metabolism were selected from the literature and assayed by quantitative real-time PCR using TaqMan gene expression assays. A subset of those with an interesting profile in seminal plasma were secondarily tested in blood.

RESULTS

Among the 11 selected miRNAs, seven were detected in seminal plasma (miR10b, miR19a, miR19b, miR34b, miR34c, miR133b, miRlet7c). A negative correlation was observed between seminal miR19a levels and metabolic syndrome, blood glucose and C-peptide. Seminal miR19b levels were also negatively correlated with metabolic syndrome. Seminal miR34c levels were negatively correlated with body mass index (BMI) and waist circumference. Seminal miR133b levels were positively correlated with BMI, waist circumference and leptin levels. Interestingly, modifications of miRNAs in seminal plasma seem specific since highlighted above correlations were not retrieved in the blood plasma for the miR19a, 19b, 10b, 34c.

CONCLUSION

Few metabolic and anthropometric disorders are correlated with the level of specific miRNAs in seminal plasma. Further studies will be required to decipher if other small non-coding RNAs may also be correlated with metabolic and anthropometric disorders and to assess their potential implication in the alteration of reproductive functions in men with obesity or metabolic disorders.

CLINICAL STUDY

Metabolic Syndrome and Male Infertility (Metasperme): Trial registration:  NCT01974947 . Registered 18 July 2013.

Personalized Nutrition in the Management of Female Infertility: New Insights on Chronic Low-Grade Inflammation

Increasing evidence on the significance of nutrition in reproduction is emerging from both animal and human studies, suggesting a mutual association between nutrition and female fertility. Different “fertile” dietary patterns have been studied; however, in humans, conflicting results or weak correlations are often reported, probably because of the individual variations in genome, proteome, metabolome, and microbiome and the extent of exposure to different environmental conditions. In this scenario, “precision nutrition”, namely personalized dietary patterns based on deep phenotyping and on metabolomics, microbiome, and nutrigenetics of each case, might be more efficient for infertile patients than applying a generic nutritional approach. In this review, we report on new insights into the nutritional management of infertile patients, discussing the main nutrigenetic, nutrigenomic, and microbiomic aspects that should be investigated to achieve effective personalized nutritional interventions. Specifically, we will focus on the management of low-grade chronic inflammation, which is associated with several infertility-related diseases.

Female obesity and infertility: outcomes and regulatory guidance

Obesity has been associated with reduced fertility, although the dynamics and mechanisms which link excess weight to reduced fertility are not yet fully clarified. Obese women, especially those with central obesity, are less likely to conceive per cycle. Obese women suffer from perturbations of the hypothalamus-pituitary-ovary axis, disturbances of the menstrual cycle and are up to three times more likely to suffer from oligo/anovulation. A delicate hormonal balance regulates follicular development and the maturation of oocytes and it has been observed that obesity can alter the hormonal environment: adipocytes, in fact, are responsible for the production of a hormone called leptin (present in high quantities in obese women) which has been associated with reduced fecundity. In addition to compromising ovulation, obesity negatively affects the development and implantation of the endometrium. The expression of polycystic ovary syndrome (PCOS) is regulated, in part, by weight, so obese women with PCOS often have a more severe phenotype and higher subfertility rates. Furthermore, obesity impairs women's response to medically assisted procreation (MAP) treatments. The authors have set out to delineate a broad-ranging overview of obesity's impact on female fertility, by drawing upon sources spanning the 1994-2022 period. Assisted reproductive technology (ART) procedures are also discussed as they relate to obese patients. In addition the dynamics by which maternal obesity reportedly affects fetal, neonatal and child development have also been briefly enunciated.

Body mass index and subfertility: multivariable regression and Mendelian randomization analyses in the Norwegian Mother, Father and Child Cohort Study

STUDY QUESTION

What is the association between BMI and subfertility?

SUMMARY ANSWER

We observed a J-shaped relationship between BMI and subfertility in both sexes, when using both a standard multivariable regression and Mendelian randomization (MR) analysis.

WHAT IS KNOWN ALREADY

High BMI in both women and men is associated with subfertility in observational studies and this relationship is further substantiated by a few small randomized controlled trials of weight reduction and success of assisted reproduction. Women with low BMI also have lower conception rates with assisted reproduction technologies.

STUDY DESIGN, SIZE, DURATION

Cohort study (the Norwegian Mother, Father and Child Cohort Study), 28 341 women and 26 252 men, recruited from all over Norway between 1999 and 2008.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women (average age 30, average BMI 23.1 kg/m2) and men (average age 33, average BMI 25.5 kg/m2) had available genotype data and provided self-reported information on time-to-pregnancy and BMI. A total of 10% of couples were subfertile (time-to-pregnancy ≥12 months).

MAIN RESULTS AND THE ROLE OF CHANCE

Our findings support a J-shaped association between BMI and subfertility in both sexes using multivariable logistic regression models. Non-linear MR validated this relationship. A 1 kg/m2 greater genetically predicted BMI was linked to 18% greater odds of subfertility (95% CI 5% to 31%) in obese women (≥30.0 kg/m2) and 15% lower odds of subfertility (-24% to -2%) in women with BMI <20.0 kg/m2. A 1 kg/m2 higher genetically predicted BMI was linked to 26% greater odds of subfertility (8-48%) among obese men. Low genetically predicted BMI values were also related to greater subfertility risk in men at the lower end of the BMI distribution. A genetically predicted BMI of 23 and 25 kg/m2 was linked to the lowest subfertility risk in women and men, respectively.

LIMITATIONS, REASONS FOR CAUTION

The main limitations of our study were that we did not know whether the subfertility was driven by the women, men or both; the exclusive consideration of individuals of northern European ancestry; and the limited amount of participants with obesity or BMI values <20.0 kg/m2.

WIDER IMPLICATIONS OF THE FINDINGS

Our results support a causal effect of obesity on subfertility in women and men. Our findings also expand the current evidence by indicating that individuals with BMI values <20 kg/m2 may have an increased risk of subfertility. These results suggest that BMI values between 20 and 25 kg/m2 are optimal for a minimal risk of subfertility.

STUDY FUNDING/COMPETING INTEREST(S)

The MoBa Cohort Study is supported by the Norwegian Ministry of Health and Care Services and the Norwegian Ministry of Education and Research. This project received funding from the European Research Council under the European Union's Horizon 2020 research and innovation program (grant agreement No 947684). It was also partly supported by the Research Council of Norway through its Centres of Excellence funding scheme, project number 262700. Open Access funding was provided by the Folkehelseinstituttet/Norwegian Institute of Public Health. D.A.L. is a UK National Institute for Health Research Senior Investigator (NF-SI-0611-10196) and is supported by the US National Institutes of Health (R01 DK10324) and a European Research Council Advanced Grant (DevelopObese; 669545). The funders had no role in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the article for publication. D.A.L. receives (or has received in the last 10 years) research support from National and International government and charitable bodies, Roche Diagnostics and Medtronic for research unrelated to the current work. The rest of the authors declare that no competing interests exist.

TRIAL REGISTRATION NUMBER

N/A.

Effects of bariatric surgery on the menstruation- and reproductive-related hormones of women with obesity without polycystic ovary syndrome: a systematic review and meta-analysis

BACKGROUND

Bariatric surgery is an effective treatment for severe obesity. Several studies have been conducted on the effects of bariatric surgery on the reproductive function of women with obesity who do not have polycystic ovary syndrome (PCOS).

OBJECTIVES

To evaluate the effects of bariatric surgery on the menstruation and reproductive related hormones of women of childbearing age with who do not have PCOS.

SETTING

A systematic review and meta-analysis at a university hospital.

METHODS

Online databases were searched for all studies reporting the efficacy of bariatric surgery for women with obesity until March 2021. The language of publication was limited to English and Chinese. Incidence of abnormal menstruation and reproductive-related hormone levels were the primary outcomes.

RESULTS

Fifteen studies comprising 725 patients were enrolled in this meta-analysis. Results showed a significantly lower incidence of abnormal menstruation (relative risk: .40, 95% confidence interval [CI]: .20-.79, P = .008) after bariatric surgery. Moreover, bariatric surgery led to a decrease in serum insulin levels (mean difference [MD] = -13.12 mIU/L, 95% CI: -15.03 to -11.22, P < .00001), glucose (MD = -.91 mmol/L, 95% CI: -1.26 to -.56, P < .00001), triglyceride (MD = -.61 g/L, 95% CI: -.76 to -.46, P < .00001), total testosterone (MD = -.22 ng/mL, 95% CI: -.24 to -.20, P < .00001), dehydroepiandrosterone (DHEA) (MD = -25.34 μg/dL, 95% CI: -31.19 to -19.49, P < .00001), estradiol (MD = -25.13 pg/mL, 95% CI: -34.13 to -16.13, P < .00001), and anti-Mullerian hormone (AMH) (MD = -.40 ng/mL, 95% CI: -.67 to -.13, P = .003). Serum sex hormone binding globulin (SHBG) levels increased after bariatric surgery (MD = 43.99 nmol/L, 95% CI: 34.99-52.99, P < .00001).

CONCLUSION

Bariatric surgery can lower fasting insulin, glucose, and triglyceride levels, reduce the incidence of abnormal menstruation, decrease total serum testosterone, DHEA, estradiol, and AMH levels, and increase SHBG level for women with obesity of childbearing age who do not have PCOS. This meta-analysis indicated that bariatric surgery could be effective in improving reproductive function for women with severe obesity.