Elevated body mass index (BMI) does not adversely affect in vitro fertilization outcome in young women

Prediction of Fertilization Disorders in the In Vitro Fertilization/Intracytoplasmic Sperm Injection: A Retrospective Study of 106,728 Treatment Cycles

Purpose

This study aimed to develop a risk prediction of fertilization disorders during the in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI).

Methods

A retrospective study was performed with 106,728 fresh embryo IVF/ICSI cycles from 2009 to 2019. Basic characteristics of patients, clinical treatment data, and laboratory parameters were involved. The associations between the selected variables and risks for low fertilization rate (LFR) and total fertilization failure (TFF) were investigated. Ordinal logistic regression and the receiver operating characteristic curves (ROCs) were used to construct and evaluate the prediction models.

Results

A total of 97,181 controls, 4,343 LFR and 5,204 TFF cases were involved in this study. The model based on clinical characteristics (the ages of the couples, women's BMI, types of infertility, ART failure history, the diminished ovarian reserve, sperm quality, insemination method, and the number of oocytes retrieved) had an AUC of 0.743 for TFF. The laboratory model showed that primary infertility, ART failure history, minimal-stimulation cycle/natural cycle, numbers of oocyte retrieved < 5, IVF, and Anti-Mullerian hormone (AMH) level < 1.1ng/ml are predictors of TFF, with an AUC of 0.742.

Conclusion

We established a clinical and a laboratory prediction model for LFR/TFF. Both of the models showed relatively high AUCs.

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.

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.

TMT-based proteomic and bioinformatic analyses of human granulosa cells from obese and normal-weight female subjects

BACKGROUND

Increasing evidence supports a relationship between obesity and either infertility or subfertility in women. Most previous omics studies were focused on determining if the serum and follicular fluid expression profiles of subjects afflicted with both obesity-related infertility and polycystic ovary syndrome (PCOS) are different than those in normal healthy controls. As granulosa cells (GCs) are essential for oocyte development and fertility, we determined here if the protein expression profiles in the GCs from obese subjects are different than those in their normal-weight counterpart.

METHODS

GC samples were collected from obese female subjects (n = 14) and normal-weight female subjects (n = 12) who were infertile and underwent in vitro fertilization (IVF) treatment due to tubal pathology. A quantitative approach including tandem mass tag labeling and liquid chromatography tandem mass spectrometry (TMT) was employed to identify differentially expressed proteins. Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were then conducted to interrogate the functions and pathways of identified proteins. Clinical, hormonal, and biochemical parameters were also analyzed in both groups.

RESULTS

A total of 228 differentially expressed proteins were noted, including 138 that were upregulated whereas 90 others were downregulated. Significant pathways and GO terms associated with protein expression changes were also identified, especially within the mitochondrial electron transport chain. The levels of free fatty acids in both the serum and follicular fluid of obese subjects were significantly higher than those in matched normal-weight subjects.

CONCLUSIONS

In GCs obtained from obese subjects, their mitochondria were damaged and the endoplasmic reticulum stress response was accompanied by dysregulated hormonal synthesis whereas none of these changes occurred in normal-weight subjects. These alterations may be related to the high FFA and TG levels detected in human follicular fluid.

Adverse effects of pre-pregnancy maternal underweight on pregnancy and perinatal outcomes in a freeze-all policy

BACKGROUND

Underweight and overweight may affect reproduction and interfere with treatment of infertility. In the present retrospective analysis, we sought to evaluate the effect of low body mass index (BMI) on pregnancy and perinatal outcomes in frozen-thawed embryo transfer (FET) cycles.

METHODS

This study involved 8755 FET cycles in a single IVF center during the period from January 2009 to December 2018. Both pregnancy and perinatal outcomes were assessed in women who were underweight, normal weight, and overweight as defined based on a respective BMI < 18.5 kg/m², ≥ 18.5 BMI < 24.9 kg/m², and BMI ≥ 25 kg/m².

RESULTS

Being underweight was linked to reduced implantation rates as compared to a normal weight (33.56% vs. 37.26%). Similarly, when comparing outcomes in underweight women to those in normal weight women, rates of clinical pregnancy (48.14% vs. 53.85%) and ongoing pregnancy (43.04% vs. 50.47%) were reduced. Rates of miscarriage were markedly reduced in the normal weight group relative to the overweight group (10.73% vs. 13.37%). Perinatal outcomes were largely comparable for all groups, with the exception of very low birth weight rates (normal weight:0.58% vs. overweight: 2.03%), very small for gestational age rates (normal weight:1.31% vs. overweight:3.55%) and very preterm delivery rates (normal weight:0.82% vs. overweight: 2.03%), which were significantly elevated for overweight mothers.

CONCLUSIONS

These results indicate that being underweight is linked to negative pregnancy outcomes when undergoing FET-based IVF.

Impact of Women Obesity and Obesity Severity on Live Birth Rate after In Vitro Fertilization

Access to in vitro fertilization (IVF) for obese women varies across centers, and the impact of obesity on IVF outcomes is widely discussed. We assessed the impact of obesity and its severity on live birth rate (LBR) after IVF. We included women treated for IVF in our center. Data were prospectively collected in the BabySentry^TM software. LBR per cycle and cumulative LBR including all attempts of the couple were calculated, considering transfer of both fresh and frozen embryos. Of 1588 included women (2379 controlled ovarian stimulations), 70.2%, 19.5%, 7.9%, and 2.4% were normal-weight, overweight, class I obesity, and class II/III obesity, respectively. For each cycle, LBR did not differ according to BMI category. Adjusted odds ratios (95% confidence intervals) for obtaining a live birth at the first cycle were 1.11 (0.78–1.58) for overweight, 1.17 (0.70–1.95) for class I obese, and 1.05 (0.48–2.31) for class II/III obese women, as compared with normal-weight women. Similarly, no significant associations were found at cycles 2, 3, and 4. Cumulative LBR increased with the number of cycles, independently of the BMI class (p log-rank = 0.91). After adjustment, obesity status did not impact significantly the miscarriage rate, regardless of the cycle. In conclusion, neither women obesity nor its severity impacted the cumulative LBR after IVF.

Effect of BMI on blood value of patients on HCG day with IUI treatment

BACKGROUND

This study aims to analyze the effect of the body mass index (BMI) on E₂, P and LH values in females who received intrauterine insemination (IUI) treatment on human chorionic gonadotropin (HCG) day.

METHODS

A total of 2319 cycles of IUI-assisted pregnancy treatment were selected in our hospital. Based on the BMI, female infertility patients are divided into three groups: normal weight group, overweight and obese group.

RESULTS

For patients with natural cycles and ≤ 35 years old, there were 440, 178 and 197 cases in the three groups, respectively. For patients with natural cycles and > 35 years old, there were 90, 83 and 81 cycles in the three groups, respectively. For patients with induced ovulation cycle and ≤ 35 years old, there were 425, 203 and 516 cases in the three groups, respectively. For patients with induced ovulation cycle and > 35 years old, there were 26, 26 and 54 cases in the three groups, respectively.

CONCLUSION

When a patient is ≤35 years old, the BMI affects the E₂, LH and P values on the day of artificial insemination. However, the BMI is negatively correlated with E₂, LH and P in IUI on HCG day. After controlling for age and assisted pregnancy, the correlation analysis revealed that the BMI is negatively correlated with hormone E₂ and LH. The higher the BMI was, the lower the levels of hormones E₂, LH and P became. However, in the present study, the BMI did not significantly improve the clinical pregnancy rate of patients who received IUI.

A systematic review and meta-analysis of lifestyle and body mass index predictors of successful assisted reproductive technologies

OBJECTIVE

Lifestyle (smoking, drinking alcohol) and body mass index (BMI) predictors of successful outcomes in assisted reproductive technology (ART) treatments were examined in this meta-analysis.

METHOD

A bibliographic search was undertaken using six databases. The review was informed by PRISMA/MOOSE guidelines. Meta-analytic data were analysed using random effects models.

RESULTS

We included 77 studies examining effects of BMI, smoking and drinking alcohol. Patients with a BMI< =24.9 were significantly more likely to achieve LB/pregnancy than with BMI> =25 OR = 1.219 (95% CI:1.128-1.319, z = 4.971, p < .001; I² = 53.779%, p = .001). Non-smokers were significantly more likely to achieve a LB or pregnancy than smokers OR = 1.457 (95% CI:1.228-1.727, z = 4.324, p < .001; I² = 51.883; p = .001). Meta-regression revealed the number of embryos transferred significantly moderated the effects of smoking on ART outcomes, and there was a trend indicating primary infertility and high BMI were also significant moderators. The evidence for drinking alcohol was inconclusive due to the small number of studies.

CONCLUSIONS

This meta-analysis confirms that ART treatment success can be predicted with lifestyle factors. Further, non-smokers' relative odds of pregnancy/live birth increase as more embryos were transferred but there was a trend that the odds of pregnancy/live birth decrease with primary infertility and high BMI.

Obesity and Outcome of Assisted Reproduction in Patients With Polycystic Ovary Syndrome

Assisted reproduction, including in vitro fertilization and intracytoplasmic sperm injection, is increasingly being used for the management of infertility in patients with polycystic ovary syndrome (PCOS). However, there are limited data regarding the association between obesity and the outcome of assisted reproduction in this specific population as well as on the effects of weight loss. The aim of the present review is to summarize the existing evidence on the association between obesity and the outcome of assisted reproduction in patients with PCOS. Accumulating data suggest that obesity is associated with lower pregnancy and live birth rates in patients with PCOS who are undergoing assisted reproduction therapy. However, it remains unclear whether weight loss improves the outcome of this therapy. Notably, recent guidelines state that the health benefits of postponing pregnancy to achieve weight loss must be balanced against the risk of declining fertility with advancing age. Therefore, if weight loss is not achieved within a reasonable time period, assisted reproduction therapy should be offered in adequately selected patients with PCOS, regardless of the presence of obesity.

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.

Overweight negatively affects outcome of superovulation treatment in female mice

Superovulatory response is characterized by a high degree of variability and unpredictability. The aim of the present experimental study was to examine whether the amount of maternal body fat can influence the efficiency of ovarian stimulation with gonadotropins. Female mice of two body condition types, normal and obese, produced in a standardized two-generation model, were subjected to ovarian stimulation using eCG and hCG followed by natural mating. Produced ova and embryos were recovered on day 1 and day 4 of pregnancy respectively, and several quantitative, qualitative and developmental parameters were evaluated in them. The overall response of mouse females with normal and elevated amounts of body fat to superovulation was similar: They produced almost the same numbers of ova and embryos on average. Conversely, a higher number of immature oocytes, non-fertilized mature oocytes and lower-stage zygotes were collected from fat females. In both groups, the majority of fertilized oocytes was able to cleave and reach the higher stages of development. However, in the group of fat mice, a lower number of blastocysts was collected, and these blastocysts showed increased incidence of apoptotic cell death. In conclusion, although the response of normal and fat mice to superovulatory treatment was similar, the quality and developmental capacities of produced ova were lower in the group of fat donors.

Should high BMI be a reason for IVF treatment denial?

Our aim was to examine the influence of BMI on the live-birth rate following IVF/ICSI and evaluate its specific contribution among other factors thus enabling accurate reproductive policy development. All patients that underwent IVF/ICSI at our center during January 2012-July 2015 were included in this retrospective study. A total of 1654 ICSI cycles were divided into four groups according to the patient's BMI (kg/m²): group I (normal weight): <25 (943 cycles); group II (overweight): 25-30 (403 cycles); group III (obese): 30-35 (212 cycles); group IV (morbid obesity): >35 (96 cycles). Comparing the four groups of BMI, mean age and number of previous ART cycles was significantly lower in group I compared to groups II, III and IV. Length of treatment was significantly shorter in group I compared to groups II, III and IV. Ovarian response to COH was comparable in terms of mean estradiol and progesterone levels on the day of hCG administration mean number of oocytes retrieved, fertilized and number of embryos transferred. Endometrial thickness was significantly lower in group IV. Outcome measures, such as implantation rate, clinical pregnancy rate (CPR) per cycle and per ET, as well as live-birth rates did not differ significantly between the groups, although in group IV LBR per cycle and per ET was lower. Multivariate logistic regression stepwise analysis found a significant correlation between age and BMI but did not find correlation between BMI and clinical pregnancy (p = 0.436) or LB (p = 0.206). The results of our relatively large retrospective study did not demonstrate a significant impact of BMI on the ART cycle outcome. Therefore, BMI should not be a basis for IVF treatment denial.

Systematic review and meta-analysis on the association of prepregnancy underweight and miscarriage

BACKGROUND

Maternal underweight, overweight and obesity have been associated with a higher risk of miscarriage. Most individual reports and all meta-analyses have addressed high body mass index.

OBJECTIVES

To review the literature and summarize the risk of miscarriage in underweight women vs those with normal weight.

METHODS

A Medline Search (1st January 1990-20th November 2015, human, in English, French, Italian, Spanish or Portuguese) was conducted. Both spontaneous pregnancies and pregnancies after assisted reproduction techniques were considered. Cohort and case control studies were included if they reported data on the outcome of interest (clinical miscarriage), in underweight and normal weight women. Information on clinical miscarriage in other body mass index categories was collected when available. Two investigators reviewed the abstracts, full text papers and extracted data. Review Manager 5.1 software was used to summarize the results.

RESULTS

32 studies (30 cohort, 2 case control) and a total of 265,760 women were included. In cohort studies, the relative risk (RR) of clinical miscarriage in underweight women was 1.08, 95% CI 1.05-1.11; p<0.0001). The corresponding figures were RR 1.09, 95% CI 1.04-1.13; p<0.0001 for overweight women and RR 1.21, 95% CI 1.15-1.27; p<0.00001 for obese women. In case control studies, the odds ratio (OR) of clinical miscarriage in underweight women was 1.02, 95% CI 0.46-2.30; p=0.95). The corresponding figures were OR 1.01, 95% CI 0.88-1.16; p=0.89 for overweight women and OR 1.26, 95% CI 1.01-1.57; p=0.04 for obese women. The limitations of this study are that it is restricted to studies with information on underweight women and that I² ranges from 0 to 91% in different subgroups.

CONCLUSION

We conclude that maternal underweight is associated with a slightly increased risk of clinical miscarriage, similar to that of overweight women and lower than the risk observed in obesity. The heterogeneity displayed in some subgroups limits the strength of the conclusion.

The Role of Overweight and Obesity in In Vitro Fertilization Outcomes of Poor Ovarian Responders

Objective. Obesity is a worldwide concern with detrimental health effects including decreased fecundity. However, obesity's impact on in vitro fertilization (IVF) is inconclusive and there is little data concerning poor ovarian responders (POR). This study explored the effects of overweight and obesity on IVF outcomes of POR. Design. We retrospectively evaluated 188 POR undergoing IVF cycles. Methods. Patients were categorized into three groups. Group 1 was normal weight POR (18.5–24.9 kg/m², n = 96); Group 2 was overweight POR (25.0–29.9 kg/m², n = 52); and Group 3 was obese POR (≥30.0 kg/m², n = 40). Main measured outcomes included IVF outcomes. Results. The oocyte maturity, total gonadotropin dose-duration, and cycle cancellation rates were similar. Obese women had significantly decreased LH levels. LH < 4 mIU/mL had a sensitivity (62%) and a specificity (86%) for IVF failure (AUC: 0.71). Fertilization rates of obese subjects were significantly lower than normal and overweight subjects (p = 0.04). Obese women's clinical pregnancy rates were significantly lower (15%) than normal weight women (33.3%, p = 0.01). Conclusions. Despite similar counts of recruited mature oocytes, obese POR women had decreased fertilization and clinical pregnancy rates. Obesity rather than overweight significantly decreased IVF outcomes in POR.

Impact of obesity on endometrial blood flow in women without polycystic ovarian syndrome during intracytoplasmic sperm injection

BACKGROUND

Obesity may exert a negative effect on in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) treatment. However, the effect of obesity on the endometrium remains unknown. This study was designed to assess the effect of isolated body mass index (BMI) on endometrial blood supply in non-polycystic ovary syndrome (PCOS) women during ICSI by power Doppler Ultrasound.

METHODS

An observational prospective study was carried out. A total of 206 patients without PCOS were divided into 4 groups based on Chinese BMI classification (kg/m(2): underweight (BMI < 18.5), normal weight (18.5 less than or equal to BMI < 24), overweight (24 less than or equal to BMI < 28), and obese (BMI greater than or equal to 28). Endometrial thickness, endometrial pattern, endometrial spiral arterial resistance index (RI) and pulsatility index (PI) values and systolic/diastolic ratio (S/D) were assessed on the day of human chorionic gonadotropin administration.

RESULTS

Obese patients required more doses of gonadotrophin and longer stimulation duration than the normal weight patients (P < 0.05). Endometrial thickness and pattern were not statistically different between the 4 BMI subgroups (P > 0.05). Subendometrial blood flow was detected in 165 (80.1%) patients and spiral arterial PI was significantly higher in the obese group than in the normal weight and underweight groups (P < 0.05). All parameters of ICSI outcome were comparable, including pregnancy and miscarriage rates.

CONCLUSIONS

Obesity (BMI greater than or equal to 28 kg/m(2)) appears to exert a negative effect on endometrial and subendometrial blood flow based on the Chinese standard of obesity; however, it seems to have no significant effect on ICSI outcomes in non-PCOS women.

Dietary lipid and cholesterol induce ovarian dysfunction and abnormal LH response to stimulation in rabbits

BACKGROUND/AIM

Excess of fat intake is dramatically increasing in women of childbearing age and results in numerous health complications, including reproductive disorders. Using rabbit does as a biomedical model, the aim of this study was to evaluate onset of puberty, endocrine responses to stimulation and ovarian follicular maturation in females fed a high fat high cholesterol diet (HH diet) from 10 weeks of age (i.e., 2 weeks before normal onset of puberty) or a control diet (C diet).

METHODOLOGY/PRINCIPAL FINDINGS

Three experiments were performed, each including 8 treated (HH group) and 8 control (C group) does. In experiment 1, the endocrine response to Gonadotropin releasing hormone (GnRH) was evaluated at 13, 18 and 22 weeks of age. In experiment 2, the follicular population was counted in ovaries of adult females (18 weeks of age). In experiment 3, the LH response to mating and steroid profiles throughout gestation were evaluated at 18 weeks of age. Fetal growth was monitored by ultrasound and offspring birth weight was recorded. Data showed a significantly higher Luteinizing hormone (LH) response after induction of ovulation at 13 weeks of age in the HH group. There was no difference at 18 weeks, but at 22 weeks, the LH response to GnRH was significantly reduced in the HH group. The number of atretic follicles was significantly increased and the number of antral follicles significantly reduced in HH does vs. controls. During gestation, the HH diet induced intra-uterine growth retardation (IUGR).

CONCLUSION

The HH diet administered from before puberty onwards affected onset of puberty, follicular growth, hormonal responses to breeding and GnRH stimulation in relation to age and lead to fetal IUGR.

Ovarian stimulation in women with high and normal body mass index: GnRH agonist versus GnRH antagonist

In modern society, obesity has become a major health problem and has been associated with impaired fertility. The aim of this study is to assess the role of obesity in women undergoing controlled ovarian hyperstimulation (COH) stimulated either with GnRH agonists or with GnRH antagonists. Records of 463 women undergoing in vitro fertilization (IVF) treatment were reviewed. The influence of body mass index (BMI) on treatment outcome was examined, after accounting for differences in stimulation protocols. In the agonist group (286 patients), the total amount of gonadotropins used was significantly higher in patients with a BMI ≥ 25 kg/m², when compared to those with a normal BMI. The same result was found in the antagonist group (177 patients). No significant differences were found in length of stimulation, number of oocytes retrieved or number of embryos transferred. In both the antagonist and the agonist group, the number of clinical pregnancies was found to be higher in patients with normal BMI, suggesting that obesity could impair the ovarian response to exogenous gonadotropins. Considering the results obtained and the many theoretical advantages of GnRH antagonists, ovarian stimulation with GnRH antagonists is an efficient treatment for both women with normal and high BMI.

BMI-related metabolic composition of the follicular fluid of women undergoing assisted reproductive treatment and the consequences for oocyte and embryo quality

STUDY QUESTION

Is the metabolic composition of the follicular fluid of women undergoing assisted reproductive treatment (ART) related to serum composition and BMI and is it associated with oocyte and embryo quality?

SUMMARY ANSWER

We showed that metabolic alterations in the serum are reflected in the follicular fluid and that some of these alterations may affect oocyte quality, irrespective of BMI.

WHAT IS KNOWN ALREADY

Many studies have focused on the effect of metabolic disorders, such as obesity and type 2 diabetes, on assisted reproduction outcomes. There are, however, only few studies focusing on the importance of the correlation between serum and follicular fluid compositions and the composition of the follicular fluid as the oocyte's micro-environment, affecting its development and subsequent embryo quality.

DESIGN, PARTICIPANTS AND SETTING

In this prospective cohort study, patient information, fertility treatment outcome data, follicular fluid and serum were obtained from women undergoing ART. Patients were categorized according to their BMI (kg/m(2)) as normal (n = 60), overweight (n = 26) or obese (n = 20). Serum and follicular fluid samples were analyzed for urea, total protein, albumin, cholesterol, high-density lipoprotein cholesterol, triglycerides, non-esterified fatty acids, apolipoprotein A1, apolipoprotein B, glucose, lactate, C-reactive protein, insulin-like growth factor -1 (IGF-1), IGF-binding protein 3 (only in follicular fluid), free carnitine and total carnitine. Metabolite concentrations in serum and follicular fluid samples were correlated and were associated with BMI and fertility treatment outcome.

MAIN RESULTS

Most serum metabolite differences between patients were reflected in the follicular fluid (P < 0.05). Follicular fluid apolipoprotein A1 and follicular fluid total protein concentrations negatively affected oocyte quality parameters (P < 0.05). However, overall BMI-related associations were poor.

BIAS, CONFOUNDING AND OTHER REASONS FOR CAUTION

In this study, we included every patient willing to participate. Within this cohort, women with a BMI transcending 35 kg/m(2) were scarce (n = 2), because extremely overweight women are mostly advised to lose weight before starting ART. Furthermore, the number of patients in each BMI group was different, possibly masking associations between the metabolic composition of serum and follicular fluid and oocyte quality parameters.

GENERALIZABILITY TO OTHER POPULATIONS

There were significant associations indicating that metabolic changes in the serum are reflected in the follicular fluid, potentially affecting oocyte quality, irrespective of the patient's BMI. For ethical reasons, this study only focused on women already in need of artificial reproductive treatment. From a metabolic point of view, we consider this cohort as a representative sample of all women of reproductive age.

STUDY FUNDING

This study was funded by the special research fund, university of Antwerp (BOF UA). None of the authors has any conflict of interest to declare.

The impact of obesity on oocytes: evidence for lipotoxicity mechanisms

Obesity can have detrimental effects on pregnancy rates in natural conceptions and also in women undergoing IVF or intracytoplasmic sperm injection (ICSI). This review summarises the most recent clinical literature investigating whether obesity impacts oocyte quality and early embryo growth. In other tissues, obesity leads to lipotoxicity responses including endoplasmic reticulum stress, mitochondrial dysfunction and apoptosis. Recent reports indicate that lipotoxicity is a mechanism by which obesity may impact oocyte quality.

Complications and outcome of assisted reproduction technologies in overweight and obese women

BACKGROUND

Based on a presumed negative impact of overweight and obesity on reproductive capacity and pregnancy outcome, some national guidelines and clinicians have argued that there should be an upper limit for a woman's BMI to access assisted reproductive technologies (ART). However, evidence on the risk of complications or expected success rate of ART in obese women is scarce. We therefore performed a systematic review on the subject.

METHODS

We searched the literature for studies reporting on complications or success rates in overweight and obese women undergoing ART. Articles were scored on methodological quality. We calculated pooled odds ratios (ORs) to express the association between overweight and obesity on the one hand, and complications and success rates of ART on the other hand. We only pooled results if data were available per woman instead of per cycle or embryo transfer.

RESULTS

We detected 14 studies that reported on the association between overweight and complications during or after ART, of which 6 reported on ovarian hyperstimulation syndrome (OHSS), 7 on multiple pregnancies and 6 on ectopic pregnancies. None of the individual studies found a positive association between overweight and ART complications. The pooled ORs for overweight versus normal weight for OHSS, multiple pregnancy and ectopic pregnancy were 1.0 [95% confidence interval (CI) 0.77-1.3], 0.97 (95% CI 0.91-1.04) and 0.96 (95% CI 0.54-1.7), respectively. In 27 studies that reported on BMI and the success of ART, the pooled ORs for overweight versus normal weight on live birth, ongoing and clinical pregnancy following ART were OR 0.90 (95% CI 0.82-1.0), 1.01 (95% CI 0.75-1.4) and OR 0.94 (95% CI 0.69-1.3), respectively.

CONCLUSIONS

Data on complications following ART are scarce and therefore a registration system should be implemented in order to gain more insight into this subject. In the available literature, there is no evidence of overweight or obesity increasing the risk of complications following ART. Furthermore, they only marginally reduce the success rates. Based on the currently available data, overweight and obesity in itself should not be a reason to withhold ART.

Body mass index and fertility: is there a correlation with human reproduction outcomes?

Considering the existing conflicts about how an elevated body mass index (BMI) affects fertility, this study had the objective of evaluating the impact of overweight and obesity on the results of IVF/ICSI (in-vitro fertilisation/intracytoplasmatic sperm injection) performed at the Human Reproduction Centre of Faculdade de Medicina do ABC. Retrospective data from 208 IVF cycles of 191 women, performed at our laboratory from February through June, 2008, were used to calculate their BMI. On the basis of the results, the patients were divided into two groups: Group 1: BMI <25 kg/m(2) and Group 2: BMI  ≥ 25 kg/m(2). Of the 208 cycles, 137 were from patients with BMI <25 kg/m(2) and 71 cycles from patients with BMI  ≥ 25 kg/m(2). Patients' ages and the number of cycles with gonadotrophin-releasing hormone agonist and antagonist were similar in both groups. The doses of follicle-stimulating hormone used for ovarian induction per cycle, the number of retrieved oocytes, fertilisation rate, embryo quality and number of transferred and frozen embryos, the hyperstimulation, pregnancy rates, miscarriage rate and live birth rates showed no statistically significant differences. BMI does not appear to be a good parameter for the definition of IVF success. The association with other methodologies may produce more consistent data about body composition and its impact on fertility.

Impact of female and male obesity on IVF/ICSI: results of 700,000 ART-cycles in Germany

To our knowledge, this is the first analysis in which male and female weights have been combined. The registry dataset covering a 12-year period was analysed for all treatment cycles where an embryo transfer was reported. In all, 706,360 cycles were analysed. Treatments include IVF, ICSI, IVF/ICSI and CPE. The highest success rate in IVF cycles was found in couples, with an obese male partner. In the group of obese women, the pregnancy rate decreased to 27.2%. Similar to IVF treatment, the highest success rate in ICSI cycles was found in couples, where either the male or the female partner was obese. The highest success rate in cycles with a cryopreserved embryo transfer was observed in couples where both partner were obese. The lowest success rate was seen where the female partner was obese. Our data analysis suggests that the combination of an obese male and a normal-weight female is positively related to better implantation rates in IVF as well as ICSI-cycles. This combination is more likely to be found in couples with a higher social status. Therefore, the increased pregnancy rate in this group might as well be related to other lifestyle factors associated with higher social status.

The adverse effects of obesity on conception and implantation

Whilst many multiparous women are obese (body mass index >30 kg/m(2)), obesity has been associated with impaired fecundity; however, the mechanism which links obesity to reduced fertility remains to be fully elucidated. Obese women, particularly those with central obesity, are less likely to conceive per cycle. Obese women suffer perturbations to the hypothalamic-pituitary-ovarian axis, menstrual cycle disturbance and are up to three times more likely to suffer oligo-/anovulation. A fine hormonal balance regulates follicular development and oocyte maturation, and it has been observed that obesity can alter the hormonal milieu. Leptin, a hormone produced by adipocytes, is elevated in obese women, and raised leptin has been associated with impaired fecundity. Obesity impairs ovulation but has also been observed to detrimentally affect endometrial development and implantation. The expression of polycystic ovary syndrome (PCOS) is regulated, in part, by weight, and so obese women with PCOS often have a more severe phenotype and experience more subfertility. Obesity also impairs the response of women to assisted conception treatments. Weight loss through lifestyle modification or bariatric surgery has been demonstrated to restore menstrual cyclicity and ovulation and improve the likelihood of conception. In this article, we will discuss the effect of obesity upon key reproductive mechanisms and its relation to fertility treatments.

The impact of body mass index on assisted reproduction

PURPOSE OF REVIEW

Obesity is a worldwide problem. The effect of obesity on the outcome of assisted reproductive techniques is quite controversial.

RECENT FINDINGS

Although there is not an absolute consensus based on evidence, obesity may lengthen the duration of ovulation induction, increase the gonadotrophin dose, decrease the peak estradiol levels, number of mature follicles and number of oocytes retrieved, and increase the cycle cancellation rate. Moreover, obesity may have a negative impact on oocyte and embryo quality. Thus, fertilization, embryo transfer, implantation and pregnancy rates have been usually found to be low in many studies. In addition, oocyte retrieval and embryo transfer procedures can be difficult due to obesity itself. Finally, miscarriage rate is found to be high. None of the studies related with obesity and assisted reproduction has been designed as a randomized controlled trial, yet. Definition of obesity, cause of infertility, protocols used for ovulation induction, starting dose for gonadotrophins, oocyte and embryo-grading systems are not standardized among the studies. Some confounding factors, such as polycystic ovary syndrome status and age, are not taken into consideration.

SUMMARY

Obesity has a negative impact on the outcomes of assisted reproductive techniques.

Bibliography. Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 February 2008 and 31 January 2009 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.