Obesity results with smaller oocyte in in vitro fertilization/intracytoplasmic sperm injection cycles-a prospective study

Pre-pubertal obesity compromises ovarian oxidative stress, DNA repair and chemical biotransformation

Obesity in adult females impairs fertility by altering oxidative stress, DNA repair and chemical biotransformation. Whether prepubertal obesity results in similar ovarian impacts is under-explored. The objective of this study was to induce obesity in prepubertal female mice and assess puberty onset, follicle number, and abundance of oxidative stress, DNA repair and chemical biotransformation proteins basally and in response to 7,12-dimethylbenz(a)anthracene (DMBA) exposure. DMBA is a polycyclic aromatic hydrocarbon that has been shown to be ovotoxic. Lactating dams (C57BL6J) were fed either a normal rodent containing 3.5% kCal from fat (lean), or a high fat diet comprised of 60% kCal from fat, and 9% kCal from sucrose. The offspring were weaned onto the diet of their dam and exposed at postnatal day 35 to either corn oil or DMBA (1 mg/kg) for 7 d via intraperitoneal injection. Mice on the HFD had reduced (P < 0.05) age at puberty onset as measured by vaginal opening but DMBA did not impact puberty onset. Heart, spleen, kidney, uterus and ovary weight were increased (P < 0.05) by obesity and liver weight was increased (P < 0.05) by DMBA exposure in obese mice. Follicle number was largely unaffected by obesity or DMBA exposure, with the exception of primary follicle number, which were higher (P < 0.05) in lean DMBA exposed and obese control relative to lean control mice. There were also greater numbers (P < 0.05) of corpora lutea in obese relative to lean mice. In lean mice, DMBA exposure reduced (P < 0.05) the level of CYP2E1, EPHX1, GSTP1, BRCA1, and CAT but this DMBA-induced reduction was absent in obese mice. Basally, obesity reduced (P < 0.05) the abundance of CYP2E1, EPHX1, GSTP1, BRCA1, SOD1 and CAT. There was greater (P < 0.05) fibrotic staining in obese DMBA-exposed ovaries and PPP2CA was decreased (P < 0.05) in growing follicles by both obesity and DMBA exposure. Thus, prepubertal obesity alters the capacity of the ovary to respond to DNA damage, ovotoxicant exposure and oxidative stress.

Association between fine particulate matter and fecundability in Henan, China: A prospective cohort study

OBJECTIVE

To investigate the relationship between ambient fine particulate matter (PM2.5) exposure and fecundability.

METHODS

This study included 751,270 female residents from Henan Province who participated in the National Free Pre-conception Check-up Projects during 2015-2017. Ambient cycle-specific PM2.5 exposure was assessed at the county level for each participant using satellite-based PM2.5 concentration data at 1-km resolution. Cox proportional hazards models with time-varying exposure were used to estimate the association between fecundability and PM2.5 exposure, adjusted for potential individual risk factors.

RESULTS

During the study period, 568,713 participants were pregnant, monthly mean PM2.5 concentrations varied from 25.5 to 114.0 µg/m3 across study areas. For each 10 µg/m3 increase in cycle-specific PM2.5, the hazard ratio for fecundability was 0.951 (95 % confidence interval: 0.950-0.953). The association was more pronounced in women who were older, with urban household registration, history of pregnancy, higher body mass index (BMI), hypertension, without exposure to tobacco, or whose male partners were older, with higher BMI, or hypertension.

CONCLUSION

In this population-based prospective cohort, ambient cycle-specific PM2.5 exposure was associated with reduced fecundability. These findings may support the adverse implications of severe air pollution on reproductive health.

Comparison of IVF/ICSI outcomes in advanced reproductive age patients with polycystic ovary syndrome and advanced reproductive age normal controls: a retrospective cohort study

BACKGROUND

At present, there are few studies on whether there is reproductive advantage in advanced polycystic ovary syndrome (PCOS) patients, and the existing research results are also controversial. Some research results show that the reproductive window of advanced reproductive age patients with polycystic ovary syndrome is longer than that of the normal control group, and the clinical pregnancy rate and cumulative live birth rate of in vitro fertilization / intracytoplasmic sperm injection(IVF/ICSI)are higher. However, some studies have contradicted the results, and believed that the clinical pregnancy rate and cumulative live birth rate in IVF/ICSI in advanced PCOS patients and normal control groups were roughly similar. This retrospective study aimed to compare IVF/ICSI outcomes in advanced reproductive age patients with PCOS and in advanced reproductive age patients with tubal factor infertility alone.

METHODS

A retrospective analysis was performed on advanced reproductive age (age ≥ 35 years) patients who received their first IVF/ICSI cycle between January 1, 2018 and December 31, 2020. This study was divided into two groups, one group was PCOS group, the other group was control group, namely tubal factor infertility group, a total of 312 patients and 462 cycles were enrolled. Compare the differences in outcomes such as cumulative live birth rate and clinical pregnancy rate between the two groups.

RESULTS

In fresh embryo transfer cycles(ET), there was no statistically significant difference in live birth rate [19/62 (30.6%) vs. 34/117 (29.1%), P = 0.825] and clinical pregnancy rate [24/62 (38.7%) vs. 43/117 (36.8%), P = 0.797] between the PCOS and control groups.In the frozen embryo transfer (FET) cycle, the difference in cumulative live birth rate [63/217 (29.0%) vs. 14/66 (21.2%), P = 0.211] and clinical pregnancy rate [74/217 (34.1%) vs. 18/66 (27.3%), P = 0.300] were not statistically significant between the two groups.

CONCLUSIONS

The IVF/ICSI outcomes of advanced reproductive age patients with PCOS are similar to those of advanced reproductive age patients with tubal factor infertility alone, and the clinical pregnancy rate and live birth rate are roughly the same. Age is an important factor that affects clinical pregnancy rate. It is recommended that patients with PCOS complicated by infertility seek medical treatment as soon as possible to obtain better pregnancy outcomes.

High-fat diet induced obesity alters Dnmt1 and Dnmt3a levels and global DNA methylation in mouse ovary and testis

Obesity impairs reproductive capacity, and the link between imprinting disorders and obesity has been discussed in many studies. Recent studies indicate that a high-fat diet may cause epigenetic changes in maternal and paternal genes, which may be transmitted to offspring and negatively affect their development. On this basis, our study aims to reveal the changes in DNA methylation and DNA methyltransferase enzymes in the ovaries and testes of C57BL/6 mice fed a high-fat diet and created a model of obesity, by comparing them with the control group. For this purpose, we demonstrated the presence and quantitative differences of DNA methyltransferase 1 and DNA methyltransferase 3a enzymes as well as global DNA methylation in ovaries and testis of C57BL/6 mice fed a high-fat diet by using immunohistochemistry and western blot methods. We found that a high-fat diet induces the levels of Dnmt1 and Dnmt3a proteins (p < 0.05). We observed increased global DNA methylation in testes but, interestingly, decreased global DNA methylation in ovaries. We think that our outcomes have significant value to demonstrate the effects of obesity on ovarian follicle development and testicular spermatogenesis and may bring a new perspective to obesity-induced infertility treatments. Additionally, to the best of our knowledge, this is the first study to document dynamic alteration of Dnmt1 and Dnmt3a as well as global DNA methylation patterns during follicle development in healthy mouse ovaries.

Oocyte diameter predicts the maturation rate of human immature oocytes collected ex vivo

Purpose

To study the impact of oocyte diameter and cumulus cell mass on the potential for final maturation of immature human oocytes in vitro.

Methods

Immature oocytes (n = 1563) from 75 women undergoing fertility preservation by ovarian tissue cryopreservation (14–41 years) were collected. After preparation of the ovarian cortex for freezing, immature oocytes were collected from the surplus medulla. After collection, IVM was performed according to standard published methods. The mass of cumulus cell surrounding the immature oocyte was grouped according to size. After IVM, each oocyte was photographed, measured, and the diameter was calculated as a mean of two perpendicular measurements.

Results

The diameter of the oocytes ranged from 60 to 171 µm with a mean of 115 µm (SD:12.1) and an interquartile range from 107 to 124 µm. The oocyte diameter was positively associated with a higher incidence of MII (p < 0.001). MII oocytes had a significantly larger mean diameter than MI, GV, and degenerated oocytes. The size of the cumulus cell mass was significantly associated with the MII stage (p < 0.001) and larger oocyte diameter (p < 0.001). The results further confirm that the diameter of the fully grown oocyte is reached relatively early in human follicular development and that the factors governing oocyte maturation in vitro are connected to the surrounding cell mass and the oocyte.

Conclusion

The diameter of the oocyte is a highly determining factor in the nuclear maturation of the human oocyte during in vitro maturation, and the size of the cumulus cell mass is closely positively associated with a larger diameter.

Preconception Dietary Patterns and Associations With IVF Outcomes: An Ongoing Prospective Cohort Study

There is a lack of research on preconception diet and reproductive outcomes conducted in the Chinese population using individual assessment. Between April 2017 and April 2020, 2,796 couples undergoing in vitro fertilization treatment were recruited in this ongoing prospective cohort, and 1,500 eligible couples were included in the final analysis. A validated semi-quantitative food frequency questionnaire was used to evaluate the maternal preconception diet. Other lifestyle factors, including smoking status, psycho-mental status, sleep quality, and physical activity, were also assessed. Five dietary patterns were identified using principal component analysis, namely "Fruits-Vegetables-Dairy-Eggs," "Fish/Seafood-Animal blood," "Tubers-Beans-Cereals," "Puffed food-Candy-Bakery," and "Dried Fruits-Organs-Rice." After adjusting for multiple confounders, we detected that the women who are more inclined to the "Fruits-Vegetables-Dairy-Eggs" pattern and less adherent to the "Tubers-Beans-Cereals" were more likely to achieve normally fertilized eggs and transferable embryos. Regarding pregnancy outcomes, we observed that a lower "Puffed food-Candy-Bakery" score and a higher "Dried fruits-Organs-Rice" score were related to a higher likelihood to achieve biochemical pregnancy. In terms of pregnancy complications, an inverse association between "Fish/Seafood-Animal blood" and hypertensive disorders was observed. We further clustered the dietary patterns based on the proportion of food groups consumed and found that dairy intake was beneficial to embryo quality, while frequent rice consumption was associated with a higher risk of macrosomia. Notably, in the stratified analysis, we observed that the positive relationship between the "Fruit-Dairy-Vegetables-Eggs" score and normal fertilization and the inverse association of the "Fish/Seafood-Animal blood" score with hypertensive disorders during pregnancy were exhibited only among women with body mass index ≥25 kg/m2. In conclusion, pre-treatment diets might be an important target for intervention to achieve a better reproductive outcome.

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.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

NAD+ Repletion Rescues Female Fertility during Reproductive Aging

Reproductive aging in female mammals is an irreversible process associated with declining oocyte quality, which is the rate-limiting factor to fertility. Here, we show that this loss of oocyte quality with age accompanies declining levels of the prominent metabolic cofactor nicotinamide adenine dinucleotide (NAD⁺). Treatment with the NAD⁺ metabolic precursor nicotinamide mononucleotide (NMN) rejuvenates oocyte quality in aged animals, leading to restoration in fertility, and this can be recapitulated by transgenic overexpression of the NAD⁺-dependent deacylase SIRT2, though deletion of this enzyme does not impair oocyte quality. These benefits of NMN extend to the developing embryo, where supplementation reverses the adverse effect of maternal age on developmental milestones. These findings suggest that late-life restoration of NAD⁺ levels represents an opportunity to rescue female reproductive function in mammals.

Declining oocyte quality is considered an irreversible feature of aging and is rate limiting for human fertility. Bertoldo et al. show that reversing an age-dependent decline in NAD(P)H restores oocyte quality, embryo development, and functional fertility in aged mice. These findings may be relevant to reproductive medicine.

Mitochondrial Ca2+ Overload Leads to Mitochondrial Oxidative Stress and Delayed Meiotic Resumption in Mouse Oocytes

Overweight or obese women seeking pregnancy is becoming increasingly common. Human maternal obesity gives rise to detrimental effects during reproduction. Emerging evidence has shown that these abnormities are likely attributed to oocyte quality. Oxidative stress induces poor oocyte conditions, but whether mitochondrial calcium homeostasis plays a key role in oocyte status remains unresolved. Here, we established a mitochondrial Ca²⁺ overload model in mouse oocytes. Knockdown gatekeepers of the mitochondrial Ca²⁺ uniporters Micu1 and Micu2 as well as the mitochondrial sodium calcium exchanger NCLX in oocytes both increased oocytes mitochondrial Ca²⁺ concentration. The overload of mitochondria Ca²⁺ in oocytes impaired mitochondrial function, leaded to oxidative stress, and changed protein kinase A (PKA) signaling associated gene expression as well as delayed meiotic resumption. Using this model, we aimed to determine the mechanism of delayed meiosis caused by mitochondrial Ca²⁺ overload, and whether oocyte-specific inhibition of mitochondrial Ca²⁺ influx could improve the reproductive abnormalities seen within obesity. Germinal vesicle breakdown stage (GVBD) and extrusion of first polar body (PB1) are two indicators of meiosis maturation. As expected, the percentage of oocytes that successfully progress to the germinal vesicle breakdown stage and extrude the first polar body during in vitro culture was increased significantly, and the expression of PKA signaling genes and mitochondrial function recovered after appropriate mitochondrial Ca²⁺ regulation. Additionally, some indicators of mitochondrial performance-such as adenosine triphosphate (ATP) and reactive oxygen species (ROS) levels and mitochondrial membrane potential-recovered to normal. These results suggest that the regulation of mitochondrial Ca²⁺ uptake in mouse oocytes has a significant role during oocyte maturation as well as PKA signaling and that proper mitochondrial Ca²⁺ reductions in obese oocytes can recover mitochondrial performance and improve obesity-associated oocyte quality.

Degenerated oocyte in the cohort adversely affects IVF outcome

The presence of Degenerated Oocyte (DEG) was mostly described after intracytoplasmic sperm injection (ICSI), with fewer reports on DEG at the time of ovum pick-up (OPU). This study aims to assess morphokinetics of embryos cultured in a time-lapse incubator and compare cohorts with and without DEG at OPU. In a retrospective cohort study from January 1, 2016 until September 31, 2017 a total of 399 IVF/ICSI cycles and 2980 embryos were evaluated. In 81 of 399 cycles at least one DEG oocyte was observed at the time of OPU. The remaining 318 cycles with no DEG oocyte were compared as a control group. In the DEG group, significantly more oocytes were collected per patient (12.9 ± 7.2 vs. 10.1 ± 6.1. P < 0.001). Fertilization rate, pregnancy and clinical pregnancy rates were comparable between the two groups, however, the morphokinetics and developmental scores of the embryos were significantly worse in the DEG group, (KID 3.4 ± 1.6 vs. 3.2 ± 1.6 P = 0.002 and ESHRE 1.5 ± 1.1 vs. 1.4 ± 1.0 P = 0.046). Significantly more patients achieved top-quality embryos in the NON DEG group (58.8% vs. 53.0%, P = 0.03), however, comparable delivery rate was achieved in both groups. In the DEG group, the frequency of DEG oocyte per cycle was negatively correlated with pregnancy rate. GnRH agonist protocol and the 17-20G needle used for OPU were significant predictors for the presence of DEG oocyte at OPU. In conclusions DEG oocyte may negatively affect IVF outcome, however, younger patients, and significantly more oocytes collected in the DEG group compensate for the IVF results.

Impact of obesity on male and female reproductive outcomes

PURPOSE OF REVIEW

The association between obesity and infertility has gained increasing provider and public awareness. The purpose of this review is to outline the recent research into the pathophysiology regarding obesity and its impact of reproductive function in both women and men.

RECENT FINDINGS

A BMI more than 25 has a detrimental impact on the hypothalamus-pituitary-gonadal (HPG) axis in both men and women, leading to alterations of HPG hormones, gametogenesis, as well as an increase in inflammation and lipotoxicity from excessive adipose tissue. Additionally, BMI likely impacts assisted reproductive technology (ART) outcomes, with a greater influence on women than men. Studies regarding weight loss interventions are heterogenous in methods and outcomes, and it is difficult to extrapolate from current data if weight loss truly leads to improved outcomes.

SUMMARY

Elevated BMI induces changes in the HPG axis, hormone levels, gametogenesis, and adverse ART outcomes. Inconsistencies regarding weight loss interventions make it difficult to assess the impact on outcomes after weight loss interventions.

Lipid droplets in granulosa cells are correlated with reduced pregnancy rates

BACKGROUND

Lipids are an important source for energy production during oocyte maturation. The accumulation of intracellular lipids binds to proteins to form lipid droplets. This may lead to cellular lipotoxicity. The impact of lipotoxicity on cumulus and granulosa cells has been reported. This pilot study evaluated their correlation to oocyte and embryo quality.

DESIGN

Prospective case-control study.

SETTING

Referral IVF unit.

PATIENTS

Women younger than age 40, undergoing IVF with intracytoplasmic sperm injection.

INTERVENTIONS

15 women with BMI > 30 (high BMI) and 26 women with BMI < 25 (low BMI) were enrolled. IVF outcomes were compared between groups based on BMI. Lipid content in cumulus and granulosa cells was evaluated using quantitative and descriptive methods. Lipid profile, hormonal profile and C-reactive protein were evaluated in blood and follicular fluid samples. Demographic and treatment data, as well as pregnancy rates were collected from electronic medical records.

RESULTS

Higher levels of LDL and CRP, slower cell division rate and lower embryo quality were found in the group with high BMI. There was no difference in pregnancy rates between groups. In light of these findings, treatment outcomes were reanalyzed according to patients who became pregnant and those who did not. We found that patients who conceived had significantly lower fat content in the granulosa cells, reflected by mean fluorescence intensity recorded by flow cytometry analysis (23,404 vs. 9370, P = 0.03).

CONCLUSIONS

BMI has no effect on lipid content in cumulus and granulosa cells, and does not affect likelihood of pregnancy. However, women who achieved pregnancy, regardless of their BMI, had lower lipid levels in their granulosa cells. This finding is important and further study is needed to evaluate lipid content in granulosa cells as a potential predictor of IVF treatment success.

Age, body weight and ovarian function affect oocyte size and morphology in non-PCOS patients undergoing intracytoplasmic sperm injection (ICSI)

The size of oocytes was previously reported to be smaller in obese women with polycystic ovary syndrome (PCOS). In the present prospective cohort study, we sought to determine whether oocyte size and morphology are associated with patient characteristics in non-PCOS women. Oocyte and oolemmal diameter were measured, enlarged perivitelline space (PVS) and ooplasmic granulation were assessed in 308 MII oocytes from 77 IVF/ICSI couples. Statistical analysis was undertaken using SAS version 9.4 (SAS institute Inc., USA). Continuous values are presented as mean ± SD and compared using a two-sample t-test or Mann-Whitney U test as appropriate. Categorical parameters are presented as proportions and compared using a Fisher exact test. Logistic and linear regression models were used to control for the effect of age for categorical and continuous variables respectively. P-value < 0.05 was considered statistically significant. Patients presented with a mean age of 40.3±5.0 years, had a BMI of 25.1±6.1 kg/m², median AMH levels of 0.6 ng/ml and produced a median of 4 oocytes. Mean total oocyte diameter was 163.2±7.4 μm (range 145.8–182.1 μm), while oolemmal diameter was 109.4±4.1 μm (range 98.5–122.3 μm). After adjusting for age and ovarian reserve increasing BMI was associated with decreased total oocyte diameter (p<0.05). Total oocyte diameter was also inversely associated with AMH levels (p = 0.03) and oocyte yield (p = 0.04). In contrast to total oocyte diameter, oolemmal diameter was not related to patient characteristics. Younger women and those with large oocyte yields demonstrated fewer oocytes with ooplasmic granulation (p<0.05 and p = 0.01). After adjustments for age, ooplasmic granulation was also less frequently observed in oocytes from women with higher AMH (p = 0.03) and increasing BMI (p<0.01). Fertilization was more likely in oocytes with larger oolemmal diameter (p = 0.008). Embryos from oocytes with larger total and ooplasmic diameters were more likely to be transferred or frozen (p = 0.004 and p = 0.01). In non-PCOS infertile women, BMI and ovarian function relate to total oocyte diameter. These results expand on previously observed associations between oocyte size and BMI in women with PCOS. They indicate the importance of detailed oocyte assessments, which may aid the currently used criteria for embryo selection and help to better understand how oocyte status is associated with later embryo development.

Obesity and recurrent miscarriage: A systematic review and meta-analysis

The aim of this study is to perform a systematic review and meta-analysis on the relationship between excess weight and risk of recurrent pregnancy loss (RPL) and to highlight the common immunological mechanisms of these two conditions. The PubMed and MEDLINE databases were searched for publications in English available as of November 2017. The search terms used were 'recurrent pregnancy loss', 'body mass index' (BMI), 'overweight' and 'obesity'. For calculation of the odds ratio (OR) and 95% confidence intervals (CI) for miscarriage in different BMI groups, RevMan software was used (Review Manager, Version 5.3.5 for Windows; The Cochrane Collaboration). In total, 100 publications including the search terms were identified. Six studies were included for qualitative analysis, and two studies were included for quantitative analysis (meta-analysis). The association between excess weight and RPL was significant (OR, 1.34; 95% CI, 1.05-1.70; P = 0.02). The isolated analyses of the groups of obese and overweight women revealed an association only between obesity and RPL (OR, 1.75; 95% CI, 1.24-2.47; P = 0.001). The data available in the current literature revealed that obese women with a history of RPL have a high risk of future pregnancy losses, a risk which was not found among overweight women.

The role of female obesity on in vitro fertilization outcomes

The aim of this review is to analyze the role of obesity on fertility outcome in women undergoing in vitro fertilization (IVF) with respect to clinical or live birth rates and pregnancy loss rates. Despite findings from several earlier and newer studies that obesity does not adversely affect pregnancy outcome in women attempting conception, numerous reports from mostly recent studies suggest that obesity undoubtedly impairs IVF outcomes. Obesity impairs ovarian responsiveness to gonadotrophin stimulation, requiring higher doses of medication, increased risk of cycle cancelation, pre-term delivery, low birth weight or miscarriage, and decreases implantation, clinical pregnancy or live birth rates compared to women of normal weight. The mechanisms underlying the adverse effects of female obesity on IVF outcome may be primarily explained by functional alterations to the hypothalamic-pituitary-ovarian axis. Additionally, obesity appears to affect deleteriously the number and quality of oocytes or embryos, and impairs endometrial decidualization which is necessary for uterine receptivity. Nevertheless, attaining normal body weight by the use of lifestyle modifications, including a healthy diet and exercise over time of several months before and during an IVF treatment, may be successful in achievement of gradual and sustainable weight loss with improvement of IVF outcome.