Effect of Female Body Mass Index on Oocyte Quantity in Fertility Treatments (IVF): Treatment Cycle Number Is a Possible Effect Modifier. A Register-Based Cohort Study

Single-cell transcriptomic profiling unveils insights into ovarian fibrosis in obese mice

BACKGROUND

Adiposity profoundly impacts reproductive health in both humans and animals. However, the precise subpopulations contributing to infertility under obese conditions remain elusive.

RESULTS

In this study, we established an obese mouse model through an eighteen-week high-fat diet regimen in adult female mice. Employing single-cell RNA sequencing (scRNA-seq), we constructed a comprehensive single-cell atlas of ovarian tissues from these mice to scrutinize the impact of obesity on the ovarian microenvironment. ScRNA-seq revealed notable alterations in the microenvironment of ovarian tissues in obese mice. Granulosa cells, stromal cells, T cells, and macrophages exhibited functional imbalances compared to the control group. We observed heightened interaction strength in the SPP1-CD44 pairing within lgfbp7+ granulosa cell subtypes and Il1bhigh monocyte subtypes in the ovarian tissues of obese mice. Moreover, the interaction strength between Il1bhigh monocyte subtypes and Pdgfrb+ stromal cell subtypes in the form of TNF - TNFrsf1α interaction was also enhanced subsequently to obesity, potentially contributing to ovarian fibrosis pathogenesis.

CONCLUSIONS

We propose a model wherein granulosa cells secrete SPP1 to activate monocytes, subsequently triggering TNF-α secretion by monocytes, thereby activating stromal cells and ultimately leading to the development of ovarian fibrosis. Intervening in this process may represent a promising avenue for improving clinical outcomes in fertility treatments for obese women.

Factors associated with oocyte recovery rates during in-vitro fertilization among Nigerian women

Introduction

the availability of oocytes is fundamental to in vitro fertilization (IVF). The factors associated with optimal or suboptimal oocyte recovery rates (ORR) in low-resource settings are not well known. This study aimed to determine the factors associated with ORR by comparing demographic and IVF cycle data of women undergoing IVF in our Centre.

Methods

this was a prospective study of 110 infertile women undergoing IVF at Nisa Premier Hospital, Abuja Nigeria, from October 2020 to September 2021. All women had reached the stage of oocyte retrieval or further, after receiving ovarian stimulation with our routine protocols. Treatment was monitored by serial transvaginal ultrasonography. The oocyte retrieval procedures were performed under conscious sedation, 36 hours after the ovulatory trigger. Optimal ORR was when eggs were obtained from at least 80% of follicles punctured. Sub-optimal ORR was when it was less than 80%. Data analyses utilized SPSS statistical software and a p-value of < 0.05 was considered significant.

Results

the mean age of all women was 34.1±4.9 years. Sixty-nine women (62.7%) had sub-optimal ORR while 41 (37.3%) had optimal ORR. Six women (5.5%) had no oocytes retrieved. Significantly more women with sub-optimal ORR were obese (70.6 vs 29.4%) and had higher follicle-stimulating hormone (FSH) levels (8.11 vs 6.34 miu/ml), p-value- 0.039. Women with sub-optimal ORR had higher mean prolactin levels (17.10 ± 13.93 miu/ml) than women with optimal ORR 11.43 ± 6.65 miu/ml), p-value- 0.019). Significantly more oocytes (5.99 vs 10.37, p-value 0.001), and MII oocytes (5.78 vs 7.56, p-value 0.035) were retrieved in women with optimal than sub-optimal ORR. The duration of stimulation, total amounts of gonadotropins administered, and fertilized oocytes were not significantly different among both groups (p-value >0.05).

Conclusion

this study has shown the factors associated with ORR in our setting to be basal FSH, prolactin, and obesity.

Planned Oocyte Cryopreservation: A Review of Current Evidence on Outcomes, Safety and Risks

Although oocyte cryopreservation was initially used as a fertility preservation strategy for medical indications, it is now is increasingly used to circumvent age-related infertility. Outcomes following planned oocyte vitrification, also known as elective egg freezing, are limited. Current studies show higher success rates for individuals undergoing fertility preservation treatment under age 35. Additionally, while freezing 20 oocytes is optimal to achieve pregnancy, freezing at least 8-10 oocytes is recommended. While fertility is not guaranteed, current evidence demonstrates that planned oocyte vitrification is an overall safe, low risk method of fertility preservation to reduce the risk for age-related infertility.

Maternal obesity: A potential disruptor of female fertility and current interventions to reduce associated risks

Currently, obesity has achieved epidemic levels in reproductive-aged women with a myriad of consequences. Obesity is susceptible to several reproductive complications that eventually affect fertility rates. These complications originate from the deteriorated quality of oocytes from mothers with obesity, which increases the probability of chromosomal aneuploidy, elevated reactive oxygen species production, compromised embryonic developmental competency, and eventually reduced fertility. Maternal obesity is linked to pregnancy complications such as implantation error, abortion, miscarriage, and early pregnancy loss. This review highlights the adverse effects of maternal obesity on female fertility, with a focus on the mechanistic link between maternal obesity and oocyte quality and discusses possible measures to reduce its associated risks.

Periconceptional biomarkers for maternal obesity: a systematic review

Periconceptional maternal obesity is linked to adverse maternal and neonatal outcomes. Identifying periconceptional biomarkers of pathways affected by maternal obesity can unravel pathophysiologic mechanisms and identify individuals at risk of adverse clinical outcomes. The literature was systematically reviewed to identify periconceptional biomarkers of the endocrine, inflammatory and one-carbon metabolic pathways influenced by maternal obesity. A search was conducted in Embase, Ovid Medline All, Web of Science Core Collection and Cochrane Central Register of Controlled Trials databases, complemented by manual search in PubMed until December 31^st, 2020. Eligible studies were those that measured biomarker(s) in relation to maternal obesity, overweight/obesity or body mass index (BMI) during the periconceptional period (14 weeks preconception until 14 weeks post conception). The ErasmusAGE score was used to assess the quality of included studies. Fifty-one articles were included that evaluated over 40 biomarkers. Endocrine biomarkers associated with maternal obesity included leptin, insulin, thyroid stimulating hormone, adiponectin, progesterone, free T4 and human chorionic gonadotropin. C-reactive protein was associated with obesity as part of the inflammatory pathway, while the associated one-carbon metabolism biomarkers were folate and vitamin B12. BMI was positively associated with leptin, C-reactive protein and insulin resistance, and negatively associated with Free T4, progesterone and human chorionic gonadotropin. Concerning the remaining studied biomarkers, strong conclusions could not be established due to limited or contradictory data. Future research should focus on determining the predictive value of the optimal set of biomarkers for their use in clinical settings. The most promising biomarkers include leptin, adiponectin, human chorionic gonadotropin, insulin, progesterone and CRP.

Comparison of two gonadotropin-releasing hormone agonist suppression protocols for in vitro fertilization in young patients with low body mass index

OBJECTIVE

To evaluate two different gonadotropin-releasing (pituitary downregulating) hormones used in in vitro fertilization (IVF) on the live birth rate in young patients with low body mass index (BMI) undergoing their first IVF cycle.

METHODS

In a retrospective study in a single public medical center, 555 long gonadotropin-releasing hormone agonist (GnRH-a) protocols were compared with 431 prolonged GnRH-a protocols between 2016 and 2018. All analyses were performed using the SPSS version 22.0. The primary measured outcome was live birth rate.

RESULTS

Compared with the long protocol, the prolonged protocol required more doses of gonadotropin and a longer duration of ovarian stimulation. Lower levels of serum luteinizing hormone and serum estrogen were detected on the day of chorionic gonadotropin administration, and a lower fertilization rate was found in the prolonged protocol. Although more oocytes were retrieved and more frozen embryos were recorded in the prolonged protocol, the live birth rate per fresh cycle was comparable between the two protocols (P = 0.057). The incidence of ovarian hyperstimulation syndrome was higher in the prolonged protocol group. In the subgroup of women with antral follicle count (AFC) of 12 or less, there was no difference in the live birth rate between the two protocols (P = 0.688). However, for women with AFC > greater than 12, the prolonged protocol was still a positive predictor of live birth rate. The odds ratio was 1.73 (95% confidence interval 1.04-2.89).

CONCLUSION

The prolonged protocol might not increase the live birth rate in women with low BMI who are undergoing their first IVF cycle. However, for women with AFC greater than 12, a prolonged protocol could be a good choice to improve the live birth rate.

The fatty acid composition in follicles is related to the developmental potential of oocytes up to the blastocyst stage: a single-centre cohort study

BACKGROUND

Advanced maternal age and obesity are associated with impaired female fertility. Moreover, fatty acids (FA) in follicular fluid (FF) play important roles in oocyte maturation and embryo development. However, the effects of body mass index (BMI), age, and FF FA composition on embryo development between days 3 and 5 and blastocyst stage on day 5 are still unclear.

METHODS

This study included 138 patients undergoing assisted reproductive technology (ART), which were divided into three BMI groups (18.5-24.9 kg/m² vs. 25.0-29.9 kg/m² vs. ≥ 30.0 kg/m²) and three age-related groups (20-30 years vs. 31-34 years vs. ≥ 35 years) which were compared for ART outcomes. Further, observations were divided into quartiles based on either of three parameters related to embryo outcome, i.e. (i) embryos developing between days 3 and 5 (ED3-5) and (ii) expanded blastocysts on day 5 (EB5), both expressed proportionally to the number of oocytes with two pronuclei (2PN), as well as (iii) the embryo utilization rate (EUR). Proportions of FF FA were then compared between Q1 and Q4, representing the quartile with the worst vs. the best embryo outcome, respectively. Finally, regression models were created to assess the relationships between BMI, age, FF total FA (TFA) concentration, relative proportions of specific FA and embryo outcome.

RESULTS

Patients of Q1 had higher proportions of FF C20:5n-3, C22:6n-3 and total n-3 PUFA than Q4 patients. Furthermore, Q4 patients tended to be younger than Q1 patients. Within the whole cohort, the proportion of C20:5n-3 negatively correlated with ED3-5/2PN and EUR, while EB5/2PN tended to be negatively correlated with age. Regression models within the overweight and obese group confirmed the negative relation between C20:5n-3 and ED3-5/2PN, but also indicated additional associations: C18:1n-9 and C20:4n-6 were positively associated with ED3-5/2PN and EUR, respectively while the proportion of C18:0 was negatively associated with EUR.

CONCLUSION

The proportions of n-3 PUFA, particularly C20:5n-3 and C22:6n-3 were reduced in the patients' quartile with the best embryo outcome. This group of patients was also younger. However, the embryo quality parameters of overweight/obese patients were not associated with age but were positively associated with FF C18:1n-9 and negatively with the proportions of C18:0 or C20:5n-3.

TRIAL REGISTRATION

This study' registration number was B670201627735.

General infertility workup in times of high assisted reproductive technology efficacy

The assessments of oocyte quality and quantity and endocrine profile have traditionally been the cornerstone of the general workup of couples with infertility. Over the years, several clinical, hormonal, and functional biomarkers have been adopted to assess ovarian function and identify endocrine disorders before assisted reproductive technology. Furthermore, the genetic workup of patients has drastically changed, introducing novel markers. This not only allowed the prediction of response to ovarian stimulation but also contributed toward the development of a safer and more efficient management of women undergoing assisted reproductive technology. The scope of this review is to provide an overview of the current and novel strategies adopted for the assessment of ovarian function and ovulatory and endocrine disorders in women planning to conceive. Furthermore, it aims to provide an insight in the role of novel genetic biomarkers and use of expanded carrier screening as part of preliminary workup of women with infertility.

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.

Association between maternal prepregnancy body mass index and pregnancy outcomes following assisted reproductive technology: A systematic review and dose-response meta-analysis

This systematic review investigated dose-response relationship between maternal prepregnancy body mass index (BMI) and pregnancy outcomes following assisted reproductive technology, including clinical pregnancy rate (CPR), miscarriage rate (MR), and live birth rate (LBR). We searched four major databases and finally included 105 studies involving more than 271,632 pregnant women. We performed linear or nonlinear dose-response meta-analyses using random effects models. At per-woman level, pooling of unadjusted estimates shown an inverted J-shaped relationship between maternal BMI and CPR; pooling of adjusted estimates showed a linear association, suggesting statistical association between higher maternal BMI and lower CPR (adjusted OR [aOR] for 5-unit increase in BMI: 0.96, 95%CI: 0.94-0.98). At per-cycle level, linear dose-response relationship was found between maternal BMI and CPR (crude relative risk, RR, [cRR] for 5-unit increase in BMI 0.97, 0.96-0.98; aOR 0.96, 0.94-0.99). Linear dose-response relationship was established between maternal BMI and the outcomes of MR or LBR (higher BMI associated with higher MR [cRR 1.15, 1.08-1.22] and lower LBR [cRR 0.91, 0.88-0.94] at per-woman level). Sensitivity analyses showed no significant changes. In conclusion, there is dose-response relationship between maternal BMI and pregnancy outcomes following assisted reproductive technology. Higher BMI values may suggest suboptimal pregnancy outcomes.

A non-linear dose-response relation of female body mass index and in vitro fertilization outcomes

PURPOSE

Obesity, measured by body mass index (BMI), is implicated in adverse pregnancy outcomes for women seeking in vitro fertilization (IVF) care. However, the shape of the dose-response relationship between BMI and IVF outcomes remains unclear.

METHODS

We therefore conducted a dose-response meta-analysis using a random effects model to estimate summary relative risk (RR) for clinical pregnancy (CPR), live birth (LBR), and miscarriage risk (MR) after IVF.

RESULTS

A total of 18 cohort-based studies involving 975,889 cycles were included. For each 5-unit increase in BMI, the summary RR was 0.95 (95% CI: 0.94-0.97) for CPR, 0.93 (95% CI: 0.92-0.95) for LBR, and 1.09 (95% CI: 1.05-1.12) for MR. There was evidence of a non-linear association between BMI and CPR (Pnon-linearity < 10-5) with CPR decreasing sharply among obese women (BMI > 30). Non-linear dose-response meta-analysis showed a relatively flat curve over a broad range of BMI from 16 to 30 for LBR (Pnon-linearity = 0.0009). In addition, we observed a J-shaped association between BMI and MR (Pnon-linearity = 0.006) with the lowest miscarriage risk observed with a BMI of 22-25.

CONCLUSIONS

In conclusion, obesity contributed to increased risk of adverse IVF outcomes in a non-linear dose-response manner. More prospective trials in evaluating the effect of body weight control are necessary.

Body fat distribution influences ART outcomes

Body mass index (BMI) is the widely used method to evaluate obesity, but it cannot differentiate lean from fat mass neither mass distribution. Other methods have been proposed for this evaluation, as waist and hip circumferences (WC, HC) and ratio (WHR) and body fat analysis by bioimpedance (BF%), but they have not been applied to evaluate assisted reproduction (ART) outcomes. The present study aims at determining whether body composition and adipose tissue distribution are better than BMI on ART outcomes. Analysis was performed through five anthropometric measurements of 788 women submitted to controlled ovarian hyperstimulation and in vitro fertilization techniques. The increase of body fat, independently of the measurement method, was associated to worse reproductive results. However, a surprising finding was that eutrophic women with WC lower than 80 cm showed gestation rates two times superior (38.9% versus 14.3%) when compared to eutrophic women with WC larger than 80 cm (p = .002). Furthermore, obese women with WHR higher than 0.85 showed worse ART results, considering oocytes retrieved, mature oocytes and fertilization when compared to those with WHR lower than 0.85. As a conclusion, it was observed that the body fat distribution, especially WC, was more relevant than BMI to predict ART outcomes.

Investigating the effect of lifestyle risk factors upon number of aspirated and mature oocytes in in vitro fertilization cycles: Interaction with antral follicle count

INTRODUCTION

There is evidence demonstrating that certain lifestyle factors have a detrimental effect on fertility. Since such factors often coexist, possible synergistic effects merit further investigation. Thus we aimed to examine the cumulative impact of lifestyle factors on in vitro fertilization (IVF) early reproductive treatment outcomes and their interaction with measures of ovarian reserve.

MATERIALS AND METHODS

By following women who were starting their first fresh IVF cycle in 2 cohorts, the "Lifestyle study cohort" (hypothesis generating cohort, n = 242) and the "UppSTART study" (validation cohort, n = 432) in Sweden, we identified two significant risk factors acting independently, smoking and BMI, and then further assessed their cumulative effects.

RESULTS

Women with both these risk factors had an Incidence Rate Ratio (IRR) of 0.75 [(95% CI 0.61-0.94)] regarding the number of aspirated oocytes compared to women without these risk factors. Concerning the proportion of mature oocytes in relation to the total number of aspirated oocytes, the interaction between BMI and Antral Follicle Count (AFC) was significant (p-value 0.045): the lower the value of AFC, the more harmful the effect of BMI with the outcome.

CONCLUSIONS

Data shows that there is an individual as well as a cumulative effect of smoking and BMI on the number of aspirated and mature oocytes in fresh IVF treatment cycles. AFC might modify associations between BMI and the proportion of mature oocytes in relation to the total number of aspirated oocytes. These results highlight the importance of lifestyle factors on IVF early reproductive outcomes and provide additional evidence for the importance of preconception guidance for the optimization of IVF cycle outcome.

Influence of body mass index in anti-Müllerian hormone levels in 951 non-polycystic ovarian syndrome women followed at a reproductive medicine unit

PURPOSE

Anti-Müllerian hormone (AMH) is a useful marker of ovarian reserve. Obesity/overweight are increasing and may affect the reproductive health. Previous studies regarding the effect of body mass index (BMI) on AMH levels are discordant. Our main goal was to evaluate the influence of BMI on AMH levels in women without polycystic ovarian syndrome.

METHODS

Revision of medical records of 951 women who performed AMH determinations as part of their fertility workup, between 2011 and 2016.

RESULTS

Median AMH concentration was 1.75 [interquartile range (IQR) 2] ng/mL (12.9 pmol/mL) and median age at AMH determination was 35 (IQR 6) years. These women evidenced a median BMI of 23 (IQR 5) kg/m². Caucasian women were more represented [889(89.3%)]. Smoking habits (present/past) were present in 359(36.1%), and 147(14.8%) harboured a history of ovarian surgery. On univariable analysis AMH was not correlated with BMI (r = 0.048/p = 0.135); the only factors influencing AMH were age (p < 0.001), ethnicity (p = 0.004), and previous ovarian surgery (p < 0.001). On multivariable analysis, age was the only variable significantly associated with AMH, evidencing a reduction of 6.2% for each additional year (p < 0.0001). Furthermore, we verified a trend suggesting an AMH reduction of 22% (p = 0.08) in black patients comparing with the caucasian ones, when controlling for the other variables.

CONCLUSION

We report one of the largest series evaluating the influence of BMI on AMH levels and, consequently, on ovarian reserve. BMI does not seem to affect AMH levels. The reported concerns on infertility in overweight and obese women may be related to follicular development/oocyte maturation or endometrial disorders, rather than decreased ovarian reserve.

The correlation between raised body mass index and assisted reproductive treatment outcomes: a systematic review and meta-analysis of the evidence

Background

Public funding for fertility services within the United Kingdom is limited, and therefore, strict guidance exists regarding who can be offered treatment under the National Health Service (NHS). Body mass index (BMI) is a universal criteria adopted by both the public and private sector.

This study addresses an important aspect of the impact of a raised BMI on fertility treatment outcomes. We standardise the analysis of the data by only including studies incorporating the WHO BMI criteria; the current reference point for clinicians and clinical commissioning groups in ascertaining which group of patients should receive treatment. This study is an update of the previous systematic review performed in 2010, with the inclusion of a larger number of cycles from central databases such as the Society for Assisted Reproductive Technology (SART).

Methods

An electronic literature search was conducted through the Cochrane, Medline and Embase libraries. Data extraction for each outcome measure was pooled and expressed as an odds ratio with 95% confidence intervals. Where clinical heterogeneity was evident, the random effects model was used to calculate the risk ratio and a fixed effects model was used for the remaining studies. A p value < 0.05 was considered statistically significant.

Results

A total of 49 studies have been identified and included in this systematic review. Overweight and obese (BMI ≥ 25 kg/m²) women have a statistically significant lower live birth rate (OR 0.81, 95% CI 0.74–0.89, p < 0.00001) following Assisted Reproductive Technology (ART) when comparisons are drawn to women with a normal BMI. An increase is also demonstrated in the number of miscarriages experienced by women with a BMI ≥ 30 kg/m² (OR 1.52, 95% CI 1.28–1.81, p < 0.00001).

Conclusion

Although this review concludes that a clear impact of BMI on ART outcomes is demonstrated, there remains questions as to the pathophysiology underlying these differences. This review supports the government’s stringent criteria regarding BMI categories under which NHS funding is made available for ART, through a clear description of poor reproductive outcomes in women with a BMI ≥ 30 kg/m².