The impact of obesity on egg quality

High fat diet-induced obesity and gestational DMBA exposure alter folliculogenesis and the proteome of the maternal ovary†

Obesity and ovotoxicant exposures impair female reproductive health with greater ovotoxicity reported in obese relative to lean females. The mother and developing fetus are vulnerable to both during gestation. 7,12-dimethylbenz[a]anthracene (DMBA) is released during carbon combustion including from cigarettes, coal, fossil fuels, and forest fires. This study investigated the hypothesis that diet-induced obesity would increase sensitivity of the ovaries to DMBA-induced ovotoxicity and determined impacts of both obesity and DMBA exposure during gestation on the maternal ovary. Female C57BL/6 J mice were fed a control or a High Sugar High Fat (45% kcal from fat; 20% kcal from sucrose) diet until ~30% weight gain was attained before mating with unexposed males. From gestation Day 7, mice were exposed intraperitoneally to either vehicle control (corn oil) or DMBA (1 mg/kg diluted in corn oil) for 7 d. Thus, there were four groups: lean control (LC); lean DMBA exposed; obese control; obese DMBA exposed. Gestational obesity and DMBA exposure decreased (P < 0.05) ovarian and increased liver weights relative to LC dams, but there was no treatment impact (P > 0.05) on spleen weight or progesterone. Also, obesity exacerbated the DMBA reduction (P < 0.05) in the number of primordial, secondary follicles, and corpora lutea. In lean mice, DMBA exposure altered abundance of 21 proteins; in obese dams, DMBA exposure affected 134 proteins while obesity alone altered 81 proteins in the maternal ovary. Thus, the maternal ovary is impacted by DMBA exposure and metabolic status influences the outcome.

Trajectory of primordial follicle depletion is accelerated in obese mice in response to 7,12-dimethylbenz[a]anthracene exposure†

Both obesity and exposure to environmental genotoxicants, such as 7,12-dimethylbenz[a]anthracene, negatively impair female reproductive health. Hyperphagic lean KK.Cg-a/a (n = 8) and obese KK.Cg-Ay/J (n = 10) mice were exposed to corn oil as vehicle control (CT) or 7,12-dimethylbenz[a]anthracene (1 mg/kg/day) for 7d intraperitoneally, followed by a recovery period. Obesity increased liver and spleen weight (P < 0.05), and 7,12-dimethylbenz[a]anthracene exposure decreased uterine weight (P < 0.05) in obese mice. Primordial follicle loss (P < 0.05) caused by 7,12-dimethylbenz[a]anthracene exposure was observed in obese mice only. Primary (lean P < 0.1; obese P < 0.05) and secondary (lean P < 0.05, obese P < 0.1) follicle loss initiated by 7,12-dimethylbenz[a]anthracene exposure continued across recovery. Reduced pre-antral follicle number in lean mice (P < 0.05), regardless of 7,12-dimethylbenz[a]anthracene exposure, was evident with no effect on antral follicles or corpora lutea number. Immunofluorescence staining of DNA damage marker, γH2AX, did not indicate ongoing DNA damage but TRP53 abundance was decreased in follicles (P < 0.05) of 7,12-dimethylbenz[a]anthracene-exposed obese mice. In contrast, increased (P < 0.05) superoxide dismutase was observed in the corpora lutea of 7,12-dimethylbenz[a]anthracene-exposed obese mice and reduced (P < 0.05) TRP53 abundance was noted in preantral and antral follicles of 7,12-dimethylbenz[a]anthracene-exposed obese mice. This study indicates that obesity influences ovotoxicity caused by a genotoxicant, potentially involving accelerated primordial follicle activation and hampering normal follicular dynamics.

The impact of offspring and maternal obesogenic diets on adult offspring oocyte mitochondrial morphology in primordial and preantral follicles

Diet-induced obesity reduces oocyte quality mainly by impacting oocyte mitochondrial functions. Moreover, maternal obesity is associated with mitochondrial dysfunction in oocytes of their adult offspring. However, these effects were reported only in fully grown oocytes, mainly in the form of abnormal mitochondrial ultrastructure. It is unknown if obesogenic (OB) diets or maternal obesity already impact the primordial and preantral follicles. Considering the long duration and dynamics of folliculogenesis, determining the stage at which oocytes are affected and the extent of the damage is crucial for optimal reproductive management of obese patients and their daughters. Potential interaction between maternal and offspring diet effects are also not described, yet pivotal in our contemporary society. Therefore, here we examined the impact of OB diets on oocyte mitochondrial ultrastructure in primordial and activated preantral follicles in offspring from diet-induced obese or lean mothers. We used an outbred Swiss mouse model to increase the pathophysiological relevance to humans. Female mice were fed control or OB diets for 7 weeks, then mated with control males. Their female offspring were fed control or OB diets after weaning for 7 weeks (2-by-2 factorial design). Adult offspring ovarian sections were examined using transmission electron microscopy. We characterised and classified unique features of oocyte mitochondrial ultrastructure in the preantral follicles. An increase in mitochondrial matrix density was the most predominant change during follicle activation in secondary follicles, a feature that is linked with a higher mitochondrial activity. Maternal obesity increased mitochondrial density already in the primordial follicles suggesting an earlier increase in bioenergetic capacity. Maternal obesity did not induce abberant ultrastructure (abnormalities and defects) in primordial or preantral follicles. In contrast, offspring OB diet increased mitochondrial abnormalities in the primordial follicles. Further investigation of the consequences of these changes on oocyte metabolic regulation and stress levels during folliculogenesis is needed.

Obesity, Dietary Patterns, and Hormonal Balance Modulation: Gender-Specific Impacts

Understanding the intricate relationship between nutrition, hormonal balance, and gender-specific factors is crucial for developing targeted interventions to mitigate obesity-related endocrine disruptions and improve metabolic health. This narrative review examines the impact of various dietary patterns on hormonal regulation in both men and women, focusing on their effects on hormonal balance and metabolic health in the context of obesity. Calorie restriction, the Western diet, high-fat diets, low-CHO diets, plant-based diets, and the Mediterranean diet are analyzed in relation to their influence on obesity-related endocrine disruptions and metabolic health. Future research directions include investigating the specific mechanisms underlying dietary influences on hormonal regulation, addressing the gender-specific metabolic differences and body fat distribution, and exploring the dietary needs of individuals undergoing gender transition. Personalized dietary interventions tailored to individual metabolic and hormonal profiles are essential for optimizing health outcomes across the gender spectrum. By integrating gender-specific considerations into dietary recommendations, healthcare professionals can better support individuals in achieving optimal metabolic health and hormonal balance.

AMPK Suppression Due to Obesity Drives Oocyte mtDNA Heteroplasmy via ATF5-POLG Axis

Due to the exclusive maternal transmission, oocyte mitochondrial dysfunction reduces fertility rates, affects embryonic development, and programs offspring to metabolic diseases. However, mitochondrial DNA (mtDNA) are vulnerable to mutations during oocyte maturation, leading to mitochondrial nucleotide variations (mtSNVs) within a single oocyte, referring to mtDNA heteroplasmy. Obesity (OB) accounts for more than 40% of women at the reproductive age in the USA, but little is known about impacts of OB on mtSNVs in mature oocytes. It is found that OB reduces mtDNA content and increases mtSNVs in mature oocytes, which impairs mitochondrial energetic functions and oocyte quality. In mature oocytes, OB suppresses AMPK activity, aligned with an increased binding affinity of the ATF5-POLG protein complex to mutated mtDNA D-loop and protein-coding regions. Similarly, AMPK knockout increases the binding affinity of ATF5-POLG proteins to mutated mtDNA, leading to the replication of heteroplasmic mtDNA and impairing oocyte quality. Consistently, AMPK activation blocks the detrimental impacts of OB by preventing ATF5-POLG protein recruitment, improving oocyte maturation and mitochondrial energetics. Overall, the data uncover key features of AMPK activation in suppressing mtSNVs, and improving mitochondrial biogenesis and oocyte maturation in obese females.

Does an increase in adipose tissue 'weight' affect male fertility? A systematic review and meta-analysis based on semen analysis performed using the WHO 2010 criteria

INTRODUCTION

Obesity negatively impact on the metabolism of sex hormones, leading to reduced testosterone serum levels. However, how the obesity could negatively impact on the overall gonadal function, particularly on male fertility, remained unclear so far.

OBJECTIVE

To systematically review evidences regarding the influence of body weight excess on the sperm production.

METHODS

A meta-analysis was conducted, searching all prospective and retrospective observational studies reporting male subjects older than 18 years old, with body weight excess from overweight to severe obesity were considered. Only studies using the V edition of the World Health Organization (WHO) manual for semen analysis interpretation were considered. No specific interventions were considered. Search was focused on studies comparing overweight/obese to normal weight subjects.

RESULTS

Twenty-eight studies were considered. Total sperm count and sperm progressive motility were significantly lower in overweight compared to normal weight subjects. Meta-regression analyses demonstrated that patients' age impacted on sperm parameters. Similarly, obese men showed lower sperm concentration, total sperm number, progressive and total motilities, and normal morphology lower than normal weight subjects. Reduced sperm concentration in obese men was influenced by age, smoking habit, varicocele, and total testosterone serum levels at meta-regression analyses.

CONCLUSIONS

The male potential fertility is reduced in subjects with increased body weight, compared to normal weight men. The higher was the increased body weight, the worst was the sperm quantity/quality. This result comprehensively included obesity among non-communicable risk factor for male infertility, shedding new lights on the negative impact of increased body weight on overall gonadal function.

Assessment of Nutritional Status and Its Influence on Ovarian Reserve: A Systematic Review

BACKGROUND

Nowadays, there is a growing interest in the relationship among lifestyle, reproductive health, and fertility. Recent investigations highlight the influence of environmental and lifestyle factors such as stress, diet, and nutritional status on reproductive health. The aim of this review was to determine the influence of nutritional status on ovarian reserve in order to improve the reproductive health of women of childbearing age.

METHODS

A systematic literature review was carried out following the PRISMA method. The quality of the studies was assessed using the Cochrane Collaboration Risk of Bias tool. Data were extracted, and the results were summarized into two blocks: according to the technique used to assess ovarian reserve and nutritional status; according to the results found in the relationship between ovarian reserve and nutritional status.

RESULTS

A total of 22 articles involving 5929 women were included. In 12 of the included articles (54.5%), a relationship between nutritional status and ovarian reserve was demonstrated. In seven publications (31.8%), the increased body mass index (BMI) led to a decrease in ovarian reserve, two of them (0.9%) in patients with polycystic ovary syndrome, showing a decrease only if BMI > 25. In two articles (0.9%), there was a negative relationship between ovarian reserve and waist-to-hip ratio, and in one (0.45%), a positive relationship was shown between ovarian reserve and testosterone levels, the latter being related to body mass index. In five articles (22.7%), body mass index was used as a confounder and was negatively related to ovarian reserve, and in another four (18%), no correlation was found.

CONCLUSIONS

Ovarian reserve appears to be influenced by nutritional status. A high body mass index has a negative impact on the ovary, decreasing antral follicle count and anti-Müllerian hormone. Oocyte quality is compromised, increasing the rate of reproductive problems and the demand for assisted reproductive techniques. Further studies are needed to understand which dietary factors have the greatest effect on ovarian reserve in order to promote reproductive health.

Obesity partially potentiates dimethylbenz[a]anthracene-exposed ovotoxicity by altering the DNA damage repair response in mice†

Obesity adversely affects reproduction, impairing oocyte quality, fecundity, conception, and implantation. The ovotoxicant, dimethylbenz[a]anthracene, is biotransformed into a genotoxic metabolite to which the ovary responds by activating the ataxia telangiectasia mutated DNA repair pathway. Basal ovarian DNA damage coupled with a blunted response to genotoxicant exposure occurs in obese females, leading to the hypothesis that obesity potentiates ovotoxicity through ineffective DNA damage repair. Female KK.Cg-a/a (lean) and KK.Cg-Ay/J (obese) mice received corn oil or dimethylbenz[a]anthracene (1 mg/kg) at 9 weeks of age for 7 days via intraperitoneal injection (n = 10/treatment). Obesity increased liver weight (P < 0.001) and reduced (P < 0.05) primary, preantral, and corpora lutea number. In lean mice, dimethylbenz[a]anthracene exposure tended (P < 0.1) to increase proestrus duration and reduced (P = 0.07) primordial follicle number. Dimethylbenz[a]anthracene exposure decreased (P < 0.05) uterine weight and increased (P < 0.05) primary follicle number in obese mice. Total ovarian abundance of BRCA1, γH2AX, H3K4me, H4K5ac, H4K12ac, and H4K16ac (P > 0.05) was unchanged by obesity or dimethylbenz[a]anthracene exposure. Immunofluorescence staining demonstrated decreased (P < 0.05) abundance of γH2AX foci in antral follicles of obese mice. In primary follicle oocytes, BRCA1 protein was reduced (P < 0.05) by dimethylbenz[a]anthracene exposure in lean mice. Obesity also decreased (P < 0.05) BRCA1 protein in primary follicle oocytes. These findings support both a follicle stage-specific ovarian response to dimethylbenz[a]anthracene exposure and an impact of obesity on this ovarian response.

Obesity is associated with alterations in antral follicle dynamics in eumenorrheic women

STUDY QUESTION

Are ovarian antral follicle dynamics altered in women with obesity and regular ovulatory cycles?

SUMMARY ANSWER

Eumenorrheic women with obesity display evidence of suppressed antral follicle dynamics as judged by fewer recruitment events, selectable follicles, and anovulatory dominant follicles, as well as lower anti-Müllerian hormone (AMH) concentrations and an increased prevalence of luteal phase defects.

WHAT IS KNOWN ALREADY

Ovarian antral follicle development is a dynamic process involving distinct follicular and endocrine events that are critical for the occurrence of regular monthly ovulations. Follicle dynamics have not been prospectively evaluated in eumenorrheic women with obesity despite the known impact of obesity on gonadotropin production, ovarian steroid hormone concentrations, and fecundity.

STUDY DESIGN, SIZE, DURATION

This was a prospective, longitudinal study of 42 women conducted over one inter-ovulatory interval (IOI).

PARTICIPANTS/MATERIALS, SETTING, METHODS

A group of 21 women with obesity (total percent body fat ≥35%) and a group of 21 women without obesity (total percent body fat <35%) underwent transvaginal ultrasonography and venipuncture every-other-day for one IOI at an academic clinical research unit. Participants were aged 19-38 years and had a history of self-reported regular menstrual cycles (21-35 days). Follicle number and diameter (≥2 mm) were quantified at each visit. Individual growth profiles for all follicles that grew to ≥7 mm were assessed. Blood samples were assayed for gonadotropins, AMH, estradiol, and progesterone.

MAIN RESULTS AND THE ROLE OF CHANCE

Women with obesity exhibited fewer recruitment events (mean ± SD, 1 ± 1 vs 2 ± 1 events; P = 0.010) and fewer selectable follicles (4 ± 3 vs 8 ± 6 follicles per participant; P = 0.022) during an IOI compared to women without obesity. AMH levels were lower in women with obesity (4.40 ± 3.01 vs 5.94 ± 2.49 ng/ml; P = 0.023), while gonadotropin profiles were similar between groups, across the IOI. Of the individual follicles tracked, fewer follicles progressed to >10 mm in the cohort with obesity (30 vs 40 follicles; P = 0.04) and fewer anovulatory follicles achieved dominance (9 vs 18 follicles; P = 0.041). Ovulatory follicles were selected at smaller diameters in women with compared to those without obesity (7.5 ± 1.6 vs 9.5 ± 1.9 mm; P = 0.001). Luteal phase defects were also more common in women with compared to those without obesity, as defined by either integrated (76 vs 29%, P = 0.002) or maximum (71 vs 24%, P = 0.002) luteal progesterone.

LIMITATIONS, REASONS FOR CAUTION

This study was limited to an assessment of antral follicle dynamics and cannot inform on earlier stages of folliculogenesis. This study was observational and cannot address causation between obesity and altered antral follicle dynamics. Lastly, the data cannot be extrapolated to account for reduced fecundity and fertility in obesity.

WIDER IMPLICATIONS OF THE FINDINGS

The increasing global prevalence of obesity necessitates an understanding of the mechanisms that underlie obesity-related adverse reproductive health outcomes. Eumenorrheic women with obesity demonstrate altered ovarian antral follicle and endocrine dynamics compared to their counterparts without obesity. The degree to which abnormal granulosa cell assembly and/or activity underlie the suboptimal luteinization and subfertility requires further investigation.

STUDY FUNDING/COMPETING INTEREST(S)

Funding was provided by Cornell University, President's Council of Cornell Women, United States Department of Agriculture (grant no. 8106), and National Institutes of Health (R01-HD0937848). B.Y.J. and H.V.B. were supported by doctoral training awards from the National Institutes of Health (T32-DK007158) and Canadian Institutes of Health Research (grant no. 146182), respectively.

TRIAL REGISTRATION NUMBER

NCT01927432, NCT01785719.

Dietary and/or physical activity interventions in women with overweight or obesity prior to fertility treatment: protocol for a systematic review and individual participant data meta-analysis

INTRODUCTION

Dietary and/or physical activity interventions are often recommended for women with overweight or obesity as the first step prior to fertility treatment. However, randomised controlled trials (RCTs) so far have shown inconsistent results. Therefore, we propose this individual participant data meta-analysis (IPDMA) to evaluate the effectiveness and safety of dietary and/or physical activity interventions in women with infertility and overweight or obesity on reproductive, maternal and perinatal outcomes and to explore if there are subgroup(s) of women who benefit from each specific intervention or their combination (treatment-covariate interactions).

METHODS AND ANALYSIS

We will include RCTs with dietary and/or physical activity interventions as core interventions prior to fertility treatment in women with infertility and overweight or obesity. The primary outcome will be live birth. We will search MEDLINE, Embase, Cochrane Central Register of Controlled Trials and trial registries to identify eligible studies. We will approach authors of eligible trials to contribute individual participant data (IPD). We will perform risk of bias assessments according to the Risk of Bias 2 tool and a random-effects IPDMA. We will then explore treatment-covariate interactions for important participant-level characteristics.

ETHICS AND DISSEMINATION

Formal ethical approval for the project (Venus-IPD) was exempted by the medical ethics committee of the University Medical Center Groningen (METc code: 2021/563, date: 17 November 2021). Data transfer agreement will be obtained from each participating institute/hospital. Outcomes will be disseminated internationally through the collaborative group, conference presentations and peer-reviewed publication.

PROSPERO REGISTRATION NUMBER

CRD42021266201.

Impact of elevated body mass index on cumulative live birth rate and obstetric safety in women undergoing assisted reproductive technology

This study evaluated the impact of elevated body mass index (BMI) on short- and long-term outcomes of in-vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) treatments. A total of 7229 patients undergoing IVF/ICSI fresh cycles and subsequent frozen embryo transfer cycles from 2014 to 2020 were divided into normal (18.5-24.9 kg/m²) and high BMI (≥ 25 kg/m²) groups. Ovarian response, pregnancy outcomes, and safety of both mother and fetus were the main outcome measures. Furthermore, multivariate analysis was used to determine whether BMI was associated with cumulative live birth rate (CLBR). Results showed that for younger women (< 38 year), CLBR was significantly reduced in the high BMI group compared with the normal BMI control and was accompanied by fewer retrieved oocytes and available embryos. Additionally, the incidence of hypertensive disorders of pregnancy, fetal macrosomia, and cleft lip and palate birth defects resulting from cumulative live births was significantly higher compared with the normal BMI group. No differences were observed among older women (≥ 38 year). Multivariate analysis revealed that high BMI was a risk factor for CLBR. Our study suggested that elevated BMI has a greater adverse impact on younger women.

The association of obesity with euploidy rates in women undergoing in vitro fertilization with preimplantation genetic testing

PURPOSE

The purpose of this study was to determine the impact of body mass index (BMI) on euploidy rates for in vitro fertilization (IVF) cycles with preimplantation genetic testing (PGT) utilizing primarily next-generation sequencing (NGS).

METHODS

This retrospective cohort study included women aged ≤ 45 years who underwent IVF/PGT between September 2013 and September 2020 at a single university-affiliated fertility center. The primary outcome was euploidy rate. Secondary outcomes included peak serum estradiol (E2), number of oocytes retrieved, oocyte maturation rate, high-quality blastulation rate, clinical loss rate (CLR), clinical pregnancy rate (CPR), and ongoing pregnancy/live birth rate (OPR/LBR).

RESULTS

The study included 1335 IVF cycles that were stratified according to BMI (normal, n = 648; overweight, n = 377; obese, n = 310). The obese group was significantly older with significantly lower baseline FSH, peak E2, high-quality blastulation rate, and number of embryos biopsied than the normal group. Overall euploidy rates were not significantly different between BMI groups (normal 36.4% ± 1.3; overweight 37.3% ± 1.8; obese 32.3% ± 1.8; p = 0.11), which persisted after controlling for covariates (p = 0.82) and after stratification of euploidy rate by age group and by number of oocytes retrieved per age group. There were no significant differences in CLR, CPR, and OPR/LBR across BMI groups.

CONCLUSIONS

Despite a lower high quality blastulation rate with obesity, there is not a significant difference in euploidy rates across BMI groups in women undergoing IVF/PGT.

Serum-Derived Exosomal microRNAs in Lipid Metabolism in Polycystic Ovary Syndrome

The crosstalk between obesity and insulin resistance (IR) in polycystic ovary syndrome (PCOS) may be related to miRNA regulation secreted by exosomes. However, the underlying mechanism remains to be explored. A model of PCOS with IR was constructed in mice with dehydroepiandrosterone (DHEA) and a high-fat diet (HFD). Serum exosomes were extracted and characterized using transmission electron microscopy (TEM) and western blot analysis (for CD9, CD63, and CD81). The expression of miR-20b-5p and miR-106a-5p in serum exosomes was detected by qRT-PCR. The effects of serum exosomal miR-20b-5p and miR-106a-5p on lipid metabolism and ovary histological structure in PCOS model with IR were also explored. Serum exosomal miR-20b-5p and miR-106a-5p overexpression could inhibit adipocyte differentiation in 3T3-L1 cells with IR and PCOS mice model. Furthermore, the predicted targets of miR-20b-5p and miR-106a-5p were also analyzed with bioinformatics. In DHEA + HFD serum-derived exosomes, the miR-20b-5p and miR-106a-5p levels were markedly decreased. Overexpression of miR-20b-5p and miR-106a-5p alleviated adipocyte differentiation-related genes and triglyceride content in 3T3-L1 cells and liver steatosis in mice. Bioinformatics analysis of miR-20b-5p and miR-106a-5p predicted targets indicated that miR-20b-5p and miR-106a-5p were highly related to lipid metabolism. Serum-derived exosome miR-20b-5p and miR-106a-5p inhibited adipocyte differentiation during the process of PCOS with IR, which might be a novel therapeutic target.

Overweight and Fertility: What We Can Learn from an Intergenerational Mouse Obesity Model

The aim of this study was to evaluate the effects of being overweight on the ability to conceive, fertilization rate, and in vivo development of embryos in regularly cycling, spontaneously ovulating, and naturally mated female mice. The study was based on statistical analysis of data collected during 14 experiments with identical design, performed on 319 control and 327 obese mice, developed in an intergenerational model of obesity induction which eliminates the impact of aging and high-fat feeding. Six-week-old mice with a vaginal sperm plug were slaughtered on embryonic days 2, 3, or 4, and the flushed contents of the oviducts and uteri were assessed by stereomicroscopy. The results showed no association between being overweight and the proportion of ovulating or fertilized females. On the other hand, a strong association was found between being overweight and ovulation yield. On embryonic day 2, significantly higher numbers of eggs were recovered from the oviducts of fertilized obese mice. Maternal overweight status was also associated with higher developmental capacities of preimplantation embryos. In conclusion, contrary to studies based on the high-fat-diet model, in female mice fed regular chow, being overweight was associated with an increased ovulation quota and higher developmental rate of fertilized oocytes. Being overweight did not impact ability to conceive. On the other hand, as documented in our previous studies, the quality of oocytes and blastocysts recovered from overweight mice developed in an intergenerational model of obesity was low.

Impact of paternal body mass index on assisted reproduction treatment outcomes: An updated systematic review and meta-analysis

AIM

The aim was to provide updated evidence on the association of male body mass index (BMI) with outcomes of assisted reproduction technology (ART).

METHODS

PubMed, Embase, and Scopus databases were systematically searched. The review included observational studies in patients undergoing ART, that is, either in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) and compared rate of clinical pregnancy and live birth based on different categories of male BMI. Quality of the pooled findings was assessed using the GRADE criteria.

RESULTS

A total of 19 studies were included in the review. Among subjects undergoing IVF, there were no significant differences in the rates of clinical pregnancy among overweight (odds ratio [OR] 1.38, 95% confidence interval [CI]: 0.65, 2.96) and obese (OR 1.86, 95% CI: 0.75, 4.58) BMI, compared to normal male BMI. Similarly, there were no significant differences in the rates of live birth among overweight (OR 1.04, 95% CI: 0.97, 1.13) and obese BMI (OR 0.90, 95% CI: 0.69, 1.18) when compared to males with normal BMI. Further, among those undergoing ICSI, there were no significant differences in the odds of clinical pregnancy among overweight (OR 0.98, 95% CI: 0.73, 1.33) and obese (OR 0.89, 95% CI: 0.62, 1.29). The odds of live births among overweight (OR 0.97, 95% CI: 0.89, 1.05) and obese (OR 0.95, 95% CI: 0.84, 1.07) male BMI were statistically similar to males with normal BMI undergoing ICSI.

CONCLUSIONS

The low to very low-quality findings suggest no significant association of overweight and obese BMI with clinical pregnancy and live birth rates among couples undergoing either IVF or ICSI.

The Quiet Embryo Hypothesis: 20 years on

This article revisits the hypothesis, proposed in 2002, that the successful development of oocytes and preimplantation mammalian embryos is associated with a metabolism which is “quiet” rather than “active”, within limits which had yet to be defined. A distinction was drawn between Functional Quietness, Loss of quietness in response to stress and Inter-individual differences in embryo metabolism and here we document applications of the hypothesis to other areas of reproductive biology. In order to encompass the requirement for “limits” and replace the simple distinction between “quiet” and “active”, evidence is presented which led to a re-working of the hypothesis by proposing the existence of an optimal range of metabolic activity, termed a “Goldilocks zone”, within which oocytes and embryos with maximum developmental potential will be located. General and specific mechanisms which may underlie the Goldilocks phenomenon are proposed and the added value that may be derived by expressing data on individual embryos as distributions rather than mean values is emphasised especially in the context of the response of early embryos to stress and to the concept of the Developmental Origins of Health and Disease. The article concludes with a cautionary note that being “quietly efficient” may not always ensure optimal embryo survival.

Mitochondrial supplementation of Sus scrofa metaphase II oocytes alters DNA methylation and gene expression profiles of blastocysts

Background

Mitochondrial DNA (mtDNA) copy number in oocytes correlates with oocyte quality and fertilisation outcome. The introduction of additional copies of mtDNA through mitochondrial supplementation of mtDNA-deficient Sus scrofa oocytes resulted in: (1) improved rates of fertilisation; (2) increased mtDNA copy number in the 2-cell stage embryo; and (3) improved development of the embryo to the blastocyst stage. Furthermore, a subset of genes showed changes in gene expression. However, it is still unknown if mitochondrial supplementation alters global and local DNA methylation patterns during early development.

Results

We generated a series of embryos in a model animal, Sus scrofa, by intracytoplasmic sperm injection (ICSI) and mitochondrial supplementation in combination with ICSI (mICSI). The DNA methylation status of ICSI- and mICSI-derived blastocysts was analysed by whole genome bisulfite sequencing. At a global level, the additional copies of mtDNA did not affect nuclear DNA methylation profiles of blastocysts, though over 2000 local genomic regions exhibited differential levels of DNA methylation. In terms of the imprinted genes, DNA methylation patterns were conserved in putative imprint control regions; and the gene expression profile of these genes and genes involved in embryonic genome activation were not affected by mitochondrial supplementation. However, 52 genes showed significant differences in expression as demonstrated by RNAseq analysis. The affected gene networks involved haematological system development and function, tissue morphology and cell cycle. Furthermore, seven mtDNA-encoded t-RNAs were downregulated in mICSI-derived blastocysts suggesting that extra copies of mtDNA affected tRNA processing and/or turnover, hence protein synthesis in blastocysts. We also showed a potential association between differentially methylated regions and changes in expression for 55 genes due to mitochondrial supplementation.

Conclusions

The addition of just an extra ~ 800 copies of mtDNA into oocytes can have a significant impact on both gene expression and DNA methylation profiles in Sus scrofa blastocysts by altering the epigenetic programming established during oogenesis. Some of these changes may affect specific tissue-types later in life. Consequently, it is important to determine the longitudinal effect of these molecular changes on growth and development before considering human clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13072-022-00442-x.

Effect of orlistat intervention on in vitro fertilization/intracytoplasmic sperm injection outcome in overweight/obese infertile women

OBJECTIVE

This retrospective study sought to evaluate the effect of orlistat intervention on the outcome of in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) in overweight/obese infertile women.

METHODS

Twenty-nine overweight/obese patients undergoing IVF/ICSI for the first time were treated with orlistat intervention (orlistat group). Another 29 patients with matched age and body mass index (BMI) were included in the control group at a ratio of 1:1. Clinical data of both groups were collected, and the clinical baseline data, IVF/ICSI cycle information and embryo transfer outcome were compared between groups by Student's t-test or chi-square test when appropriate.

RESULTS

The 29 patients in the orlistat group completed 37 embryo transfer cycles, and the 29 subjects in the control group completed 38 embryo transfer cycles. There was no significant difference in the clinical baseline data or IVF/ICSI cycle data between the two groups (p > .05). In the end, 22 transfer cycles in orlistat group obtained clinical pregnancies, 5 obtained biochemical pregnancies and 10 had non-pregnancies. As for the control group, 15 transfer cycles obtained clinical pregnancies, 15 achieved biochemical pregnancies and 8 had non-pregnancies. The clinical pregnancy rate of the orlistat group was significantly higher than that of the control group (59.46% versus 39.47%, p = .004), but there was no significant difference in the live birth rate between the two groups (54.05% versus 36.84%, p > .05).

CONCLUSIONS

Orlistat intervention for overweight/obese infertile women receiving IVF/ICSI treatment will increase the clinical pregnancy rate, without affecting the total amount of gonadotropins, ovarian stimulation time or the follicular output rate (FORT).

Gene cascade analysis in human granulosa tumor cells (KGN) following exposure to high levels of free fatty acids and insulin

Maternal metabolic disorders such as obesity and diabetes are detrimental factors that compromise fertility and the success rates of medically assisted procreation procedures. During metabolic stress, adipose tissue is more likely to release free fatty acids (FFA) in the serum resulting in an increase of FFA levels not only in blood, but also in follicular fluid (FF). In humans, high concentrations of palmitic acid and stearic acid reduced granulosa cell survival and were associated with poor cumulus-oocyte complex (COC) morphology. Obesity and high levels of circulating FFA were also causatively linked to hampered insulin sensitivity in cells and compensatory hyperinsulinemia. To provide a global picture of the principal upstream signaling pathways and genomic mechanisms involved in this metabolic context, human granulosa-like tumor cells (KGN) were treated with a combination of palmitic acid, oleic acid, and stearic acid at the higher physiological concentrations found in the follicular fluid of women with a higher body mass index (BMI) (≥ 30.0 kg/m2). We also tested a high concentration of insulin alone and in combination with high concentrations of fatty acids. Transcription analysis by RNA-seq with a cut off for fold change of 1.5 and p-value 0.05 resulted in thousands of differentially expressed genes for each treatment. Using analysis software such as Ingenuity Pathway Analysis (IPA), we were able to establish that high concentrations of FFA affected the expression of genes mainly related to glucose and insulin homoeostasis, fatty acid metabolism, as well as steroidogenesis and granulosa cell differentiation processes. The combination of insulin and high concentrations of FFA affected signaling pathways related to apoptosis, inflammation, and oxidative stress. Taken together, our results provided new information on the mechanisms that might be involved in human granulosa cells exposed to high concentrations of FFA and insulin in the contexts of metabolism disorders.

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.

Mean differences in maternal body mass index and recurrent pregnancy loss: a systematic review and meta-analysis of observational studies

OBJECTIVE

To investigate the association of maternal body mass index (BMI) and recurrent pregnancy loss (RPL).

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

A total of 3,833 women with RPL and 4,083 women as controls.

INTERVENTION(S)

Studies were identified through a search of PubMed, Embase, Scopus, and Cochrane.

MAIN OUTCOME MEASURE(S)

The primary outcome of interest was RPL using the mean differences in maternal BMI as the predictor variable. The results of the meta-analysis were reported as the mean difference with a 95% confidence interval.

RESULT(S)

In total, 892 studies were reviewed. Pooled data from 25 studies suggested that the maternal BMI of women with a history of recurrent pregnancy loss was significantly higher than the BMI of controls, mean difference 0.7 kg/m² [95% confidence interval 0.2-1.3].

CONCLUSION(S)

These findings supported an association between maternal BMI and RPL. Large prospective studies are needed to evaluate the influence of maternal BMI on pregnancy outcomes in women with RPL.

Association Between Periconceptional Weight of Maternal Grandmothers and Attention-Deficit/Hyperactivity Disorder in Grandchildren

IMPORTANCE

Neurodevelopmental disorders have been proposed to involve alterations to epigenetic regulation, and epigenetic effects may extend to germline cells to affect later generations. Weight status may affect DNA methylation, and maternal weight before and during pregnancy has been associated with offspring DNA methylation as well as attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVE

To assess whether a woman's weight before and during pregnancy is associated with ADHD in her grandchild.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study analyzed data from 19 835 grandmother-mother dyads and 44 720 grandchildren in the Nurses' Health Study II (NHS-II) cohort (2001-2013), a population-based prospective cohort study. Cluster-weighted generalized estimating equations were modeled to estimate the association of grandmother's prepregnancy body mass index (BMI) and gestational weight gain with grandchild risk of ADHD. Data analyses were conducted from May 2018 to April 2021. Grandmothers reported their height and weight before, and weight gain during, their pregnancy with the NHS-II participants. Mothers self-reported height and weight prior to pregnancy. From those data, grandmother BMI and mother BMI were calculated as weight in kilograms divided by height in meters squared and categorized as underweight (<18.5), healthy/normal (18.5-24.9), overweight (25.0-29.9), or obese (≥30).

MAIN OUTCOMES AND MEASURES

Cases of ADHD identified by maternal report of having a child with a diagnosis of ADHD.

RESULTS

In total, 19 835 grandmothers (97.6% White race/ethnicity; 2113 [10.7%] prepregnancy underweight and 1391 [7.0%] prepregnancy overweight or obese) were included in this cohort study. Of 44 720 grandchildren, 3593 (8%) received a diagnosis of ADHD. Higher odds of ADHD among grandchildren were found for those whose grandmother was underweight compared with healthy weight prior to pregnancy with the NHS-II participant (adjusted odds ratio, 1.25; 95% CI, 1.10-1.42). By contrast, grandmother gestational weight gain was not significantly associated with risk of grandchild ADHD (adjusted odds ratio for <20 lbs [9.1 kg], 1.06; 95% CI, 0.96-1.16; adjusted odds ratio for >29 lbs [13.2 kg], 1.01; 95% CI, 0.91-1.13). Mother prepregnancy BMI showed an association with ADHD among offspring, with a stronger association detected for obese status (adjusted odds ratio, 1.27; 95% CI, 1.07-1.49) than for overweight status (adjusted odds ratio, 1.13; 95% CI, 1.02-1.26) compared with normal weight as a reference group. The positive association between grandmother prepregnancy underweight and ADHD risk among the grandchildren remained unchanged after further adjustment for potential mediators, including maternal prepregnancy BMI.

CONCLUSIONS AND RELEVANCE

The results of this cohort study indicate that grandmother underweight prior to pregnancy is associated with an increased risk of ADHD among grandchildren, independent of grandmother gestational weight gain and independent of maternal prepregnancy weight status.

Oocyte maturation under lipotoxic conditions induces carryover transcriptomic and functional alterations during post-hatching development of good-quality blastocysts: novel insights from a bovine embryo-transfer model

STUDY QUESTION

Does oocyte maturation under lipolytic conditions have detrimental carry-over effects on post-hatching embryo development of good-quality blastocysts after transfer?

SUMMARY ANSWER

Surviving, morphologically normal blastocysts derived from bovine oocytes that matured under lipotoxic conditions exhibit long-lasting cellular dysfunction at the transcriptomic and metabolic levels, which coincides with retarded post-hatching embryo development.

WHAT IS KNOWN ALREADY

There is increasing evidence showing that following maturation in pathophysiologically relevant lipotoxic conditions (as in obesity or metabolic syndrome), surviving blastocysts of good (transferable) morphological quality have persistent transcriptomic and epigenetic alteration even when in vitro embryo culture takes place under standard conditions. However, very little is known about subsequent development in the uterus after transfer.

STUDY DESIGN, SIZE, DURATION

Bovine oocytes were matured in vitro in the presence of pathophysiologically relevant, high non-esterified fatty acid (NEFA) concentrations (HIGH PA), or in basal NEFA concentrations (BASAL) as a physiological control. Eight healthy multiparous non-lactating Holstein cows were used for embryo transfers. Good-quality blastocysts (pools of eight) were transferred per cow, and cows were crossed over for treatments in the next replicate. Embryos were recovered 7 days later and assessed for post-hatching development, phenotypic features and gene expression profile. Blastocysts from solvent-free and NEFA-free maturation (CONTROL) were also tested for comparison.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Recovered Day 14 embryos were morphologically assessed and dissected into embryonic disk (ED) and extraembryonic tissue (EXT). Samples of EXT were cultured for 24 h to assess cellular metabolic activity (glucose and pyruvate consumption and lactate production) and embryos' ability to signal for maternal recognition of pregnancy (interferon-τ secretion; IFN-τ). ED and EXT samples were subjected to RNA sequencing to evaluate the genome-wide transcriptome patterns.

MAIN RESULTS AND THE ROLE OF CHANCE

The embryo recovery rate at Day 14 p.i. was not significantly different among treatment groups (P > 0.1). However, higher proportions of HIGH PA embryos were retarded in growth (in spherical stage) compared to the more elongated tubular stage embryos in the BASAL group (P < 0.05). Focusing on the normally developed tubular embryos in both groups, HIGH PA exposure resulted in altered cellular metabolism and altered transcriptome profile particularly in pathways related to redox-regulating mechanisms, apoptosis, cellular growth, interaction and differentiation, energy metabolism and epigenetic mechanisms, compared to BASAL embryos. Maturation under BASAL conditions did not have any significant effects on post-hatching development and cellular functions compared to CONTROL.

LARGE-SCALE DATA

The datasets of RNA sequencing analysis are available in the NCBI's Gene Expression Omnibus (GEO) repository, series accession number GSE127889 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE127889). Datasets of differentially expressed genes and their gene ontology functions are available in the Mendeley datasets at http://dx.doi.org/10.17632/my2z7dvk9j.2.

LIMITATIONS, REASONS FOR CAUTION

The bovine model was used here to allow non-invasive embryo transfer and post-hatching recovery on Day 14. There are physiological differences in some characteristics of post-hatching embryo development between human and cows, such as embryo elongation and trophoblastic invasion. However, the main carry-over effects of oocyte maturation under lipolytic conditions described here are evident at the cellular level and therefore may also occur during post-hatching development in other species including humans. In addition, post-hatching development was studied here under a healthy uterine environment to focus on carry-over effects originating from the oocyte, whereas additional detrimental effects may be induced by maternal metabolic disorders due to adverse changes in the uterine microenvironment. RNA sequencing results were not verified by qPCR, and no solvent control was included.

WIDER IMPLICATIONS OF THE FINDINGS

Our observations may increase the awareness of the importance of maternal metabolic stress at the level of the preovulatory oocyte in relation to carry-over effects that may persist in the transferrable embryos. It should further stimulate new research about preventive and protective strategies to optimize maternal metabolic health around conception to maximize embryo viability and thus fertility outcome.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Flemish Research Fund (FWO grant 11L8716N and FWO project 42/FAO10300/6541). The authors declare there are no conflicts of interest.

Revisiting the Impact of Local Leptin Signaling in Folliculogenesis and Oocyte Maturation in Obese Mothers

The complex nature of folliculogenesis regulation accounts for its susceptibility to maternal physiological fitness. In obese mothers, progressive expansion of adipose tissue culminates with severe hyperestrogenism and hyperleptinemia with detrimental effects for ovarian performance. Indeed, maternal obesity is associated with the establishment of ovarian leptin resistance. This review summarizes current knowledge on potential effects of impaired leptin signaling throughout folliculogenesis and oocyte developmental competence in mice and women.

Prevalence of premature ovarian insufficiency and its determinants in Iranian populations: Tehran lipid and glucose study

BACKGROUND

Premature ovarian insufficiency (POI) considered as a concerning health issue for women of reproductive age. In this study we aim to estimate the prevalence of POI and assessing the influential factors.

METHODS

Data was obtained from Tehran lipid and glucose study (TLGS). All eligible post-menarcheal female participants of the TLGS, ages 20-65, were recruited (n = 6521). Participants were followed for the event of menopause, and age at menopause was recorded. Kaplan Meier analysis was applied to estimate mean and median for age at menopause. Weibull accelerated failure time survival regression model (AFT), was applied to assess influential determinants of POI. Conditional probability approach was used to provide estimation for prevalence of POI.

RESULTS

In this population-based study, the prevalence of POI (menopause age < 40 years) and early menopause (menopause age < 45 years) were estimated 3.5% and 24.6%, respectively. AFT model showed that in comparison to normal weight women, time to menopause was decreased by - 0.09 year (95% CI - 0.27, - 0.01, p = 0.023) and - 0.03 year (95% CI - 0.05, - 0.02, p = 0.000) in underweight and overweight women, respectively. Moreover, time to natural menopause was increased by 0.12 year (95% CI 0.07 to 0.17, p = 0.000) in women used oral contraceptives for > 6 months.

CONCLUSION

About one quartile of Iranian women experienced menopause at an age less than 45, especially the non-normal weight ones; this high prevalence is a critical public health concerns that needs to be addressed by health policy makers.

Nuclear receptors linking physiology and germline stem cells in Drosophila

Maternal nutrition and physiology are intimately associated with reproductive success in diverse organisms. Despite decades of study, the molecular mechanisms linking maternal diet to the production and quality of oocytes remain poorly defined. Nuclear receptors (NRs) link nutritional signals to cellular responses and are essential for oocyte development. The fruit fly, Drosophila melanogaster, is an excellent genetically tractable model to study the relationship between NR signaling and oocyte production. In this review, we explore how NRs in Drosophila regulate the earliest stages of oocyte development. Long-recognized as an essential mediator of developmental transitions, we focus on the intrinsic roles of the Ecdysone Receptor and its ligand, ecdysone, in oogenesis. We also review recent studies suggesting broader roles for NRs as regulators of maternal physiology and their impact specifically on oocyte production. We propose that NRs form the molecular basis of a broad physiological surveillance network linking maternal diet with oocyte production. Given the functional conservation between Drosophila and humans, continued experimental investigation into the molecular mechanisms by which NRs promote oogenesis will likely aid our understanding of human fertility.

Cellular uptake of polymeric nanoparticles by bovine cumulus-oocyte complexes and their effect on in vitro developmental competence

Polymeric nanoparticles (NPs) are produced using bio-compatible and bio-degradable materials such as PLGA (Poly(lactic-co-glycolic acid)). This technology provides a valuable tool to deliver molecules to the subcellular level with a relatively low risk of cytotoxicity. However their use in the field of reproductive biotechnology is not yet scientifically substantiated. The aim of the present study was to test if PLGA NPs can be taken-up by cumulus-enclosed oocytes as a first step towards potential oocyte-targeted applications to enhance oocyte quality and fertility. We conducted a series of experiments using bovine in vitro oocyte maturation as a model to study FITC-conjugated PLGA internalization (using laser-scanning confocal microscopy) and the effect of some important physical (particle size) and chemical (conjugation with PEG) modifications. We show evidence that PLGA NPs can be taken-up by cumulus cells and to a less extent by the enclosed oocytes regardless of the NP size. The NP transfer to the oocyte appear to be transcellular (via cumulus cells and transzonal projections) and paracellular (via zona pellucida). The PLGA NPs were detected in the vicinity of the oocyte as quick as 2 h post-exposure in a protein-free medium and did not compromise cumulus cell viability nor subsequent early embryo development or embryo quality. These results suggest that PLGA NPs may have promising applications as carriers for drug or molecule delivery targeting cumulus cells and oocytes.

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

CONTEXT

Despite several studies documenting that obesity affects female and male fertility and leads to multiple adverse reproductive outcomes, the mechanisms involved are not elucidated. We aimed to summarize the potential adverse effects of female and male obesity, as well as the impact of weight loss on their fertility status.

EVIDENCE ACQUISITION

This review summarizes papers investigating the potential adverse effects of female and male obesity and the impact of weight-loss interventions on fertility among reproductive age populations. PubMed, Scopus, Web of Science, and Google Scholar databases were searched for retrieving studies published up to November 2019 on obesity/overweight among reproductive age populations.

RESULTS

The review of 68 studies revealed that female and male obesity/overweight increases the risk of sub-fecundity and infertility. The destructive effects of female obesity on reproduction are attributed to a variety of ovarian and extra-ovarian factors. In women with overweight or obesity, the time taken to conceive is longer, and they have a decreased fertility rate, increased requirement for gonadotropins, and higher miscarriage rate when compared to those with normal weight. Male obesity may lead to subfertility, mainly because of the disruption of the hypothalamus-pituitary-gonadal (HPG) axis, increased testicular temperature, impairment of the physical and molecular structure of sperm, decreased sperm quality, and erectile dysfunction due to peripheral vascular disease. Most studies recommend lifestyle interventions as first-line therapy in the general population of women and men with obesity and infertility.

CONCLUSIONS

This study shows the negative effects of female and male overweight and obesity on fertility. Therefore, educational interventions on the adverse effects of obesity and the benefits of weight reduction, such as increasing pregnancy rate, should be considered for couples seeking fertility.

Does an FSH surge at the time of hCG trigger improve IVF/ICSI outcomes? A randomized, double-blinded, placebo-controlled study

STUDY QUESTION

Does an artificially induced FSH surge at the time of hCG trigger improve IVF/ICSI outcomes?

SUMMARY ANSWER

An additional FSH bolus administered at the time of hCG trigger has no effect on clinical pregnancy rate, embryo quality, fertilization rate, implantation rate and live birth rate in women undergoing the long GnRH agonist (GnRHa) protocol for IVF/ICSI.

WHAT IS KNOWN ALREADY

Normal ovulation is preceded by a surge in both LH and FSH. Few randomized clinical trials have specifically investigated the role of the FSH surge. Some studies indicated that FSH given at hCG ovulation trigger boosts fertilization rate and even prevents ovarian hyperstimulation syndrome (OHSS).

STUDY DESIGN, SIZE, DURATION

This was a randomized, double-blinded, placebo-controlled trial conducted at a single IVF center, from June 2012 to November 2013. A sample size calculation indicated that 347 women per group would be adequate. A total of 732 women undergoing IVF/ICSI were randomized, using electronically randomized tables, to the intervention or placebo groups. Participants and clinical doctors were blinded to the treatment allocation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients aged ≤42 years who were treated with IVF/ICSI owing to tubal factor, male factor, unexplained, endometriosis and multiple factors were enrolled in this trial. Subjects all received a standard long GnRHa protocol for IVF/ICSI and hCG 6000–10 000 IU to trigger oocyte maturation. A total of 364 and 368 patients were randomized to receive a urinary FSH (uFSH) bolus (6 ampules, 450 IU) and placebo, respectively, at the time of the hCG trigger. The primary outcome measure was clinical pregnancy rate. The secondary outcome measures were FSH level on the day of oocyte retrieval, number of oocytes retrieved, good-quality embryo rate, live birth rate and rate of OHSS.

MAIN RESULTS AND THE ROLE OF CHANCE

There were no significant differences in the baseline demographic characteristics between the two study groups. There were also no significant differences between groups in cycle characteristics, such as the mean number of stimulation days, total gonadotrophin dose and peak estradiol. The clinical pregnancy rate was 51.6% in the placebo group and 52.7% in the FSH co-trigger group, with an absolute rate difference of 1.1% (95% CI −6.1% to 8.3%). The number of oocytes retrieved was 10.47 ± 4.52 and 10.74 ± 5.01 (P = 0.44), the rate of good-quality embryos was 37% and 33.9% (P = 0.093) and the implantation rate was 35% and 36% (P = 0.7) in the placebo group and the FSH co-trigger group, respectively.

LIMITATIONS, REASONS FOR CAUTION

This was a single-center study, which may limit its effectiveness. The use of uFSH is a limitation, as this is not the same as the natural FSH. We did not collect follicular fluid for further study of molecular changes after the use of uFSH as a co-trigger.

WIDER IMPLICATIONS OF THE FINDINGS

Based on previous data and our results, an additional FSH bolus administered at the time of hCG trigger has no benefit on clinical pregnancy rates in women undergoing the long GnRHa protocol in IVF/ICSI: a single hCG trigger is sufficient.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Key Research and Development Program of China (2016YFC1000205); Sun Yat-Sen University Clinical Research 5010 Program (2016004); the Science and Technology Project of Guangdong Province (2016A020216011 and 2017A020213028); and Science Technology Research Project of Guangdong Province (S2011010004662). There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

The trial was registered in the Chinese Clinical Trial Registry (ChiCTR-TRC-12002246).

TRIAL REGISTRATION DATE

20 May 2012.

DATE OF FIRST PATIENT’S ENROLMENT

10 June 2012.

Cumulative Live Birth Rates According to Maternal Body Mass Index After First Ovarian Stimulation for in vitro Fertilization: A Single Center Analysis of 14,782 Patients

Objective: To investigate the cumulative live birth rates (CLBR) according to body mass index (BMI) in women undergoing their first in vitro fertilization (IVF). Design: Retrospective cohort analysis. Setting: An IVF clinic in a public hospital. Patients: This is a retrospective study of 14,782 patients undergoing their first fresh IVF cycles and subsequent frozen embryo transfers in our clinic from January 2014 to January 2017. The follow-up for CLBR continued until January 2019. Patients with a BMI <18.5 kg/m2 were considered to be underweight and those with a BMI > 24 kg/m2 were considered to be overweight. Patients with a BMI ≥ 28 kg/m2 were considered to be obese. Intervention(s): None. Primary Outcome Measure: The primary outcome was cumulative live birth rate (CLBR). Result(s): This study illustrated the "inverted U shape" associations between body weight and IVF outcome (CLBR). The turning points in threshold analysis, as found by an automatic search, were BMIs of 18.5 and 30.4 kg/m2. The main finding of this retrospective data analysis is that the CLBR increased in underweight women, plateaued for normal weight and overweight women with a BMI between 18.5 and 30.4 kg/m2, and decreased in obese women. Conclusion(s): The data suggested an "inverted U shape" association between BMI and CLBR. The CLBR increases in underweight women, plateaus in normal weight and overweight women, and then decreases in obese women.

Male partners of subfertile couples in which the spouse is obese display adverse weight and lifestyle associated with reduced sperm quality

OBJECTIVES

To assess: 1-the spousal concordance of lifestyle and anthropometric characteristics between partners of infertile couples in which the woman is obese; and 2-in men, the influence of these characteristics on their conventional seminal parameters.

DESIGN

Cross-sectional study.

SETTING

Fertility clinic of the Centre hospitalier universitaire de Sherbrooke, Canada, between January 2012 and February 2015.

PATIENTS

97 infertile heterosexual couples in which women were obese and seeking fertility treatments.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Weight and percentage of fat mass were evaluated using a scale with foot-to-foot bio-impedance. Abdominal obesity was estimated with waist circumference and lifestyle habits, by a self-reported questionnaire. Seminal parameters were analysed and collected according to the WHO guidelines (Kruger's strict criteria for seminal morphology).

RESULTS

There was a significant spousal concordance for the percentage of fat mass, leisure activities and overall nutritional quality. Accordingly, male participants displayed anthropometric and lifestyle characteristics at higher risk than Canadian men of similar age. Moreover, BMI, daily consumption of fruits & vegetables and sleeping hours in men were independently associated to the total motile sperm count.

CONCLUSION

This is the first study to report concordance for anthropometric and lifestyle characteristics between partners of infertile couples in which the woman is obese. These characteristics in men were more adverse than in the general population and were associated with reduced sperm quality. Altogether, our results suggest that male partners of infertile couples could benefit from participating in the lifestyle intervention that is already recommended for their spouse affected by obesity.

CAPSULE

Because partners of subfertile couples in which the woman is obese share adverse anthropometric and lifestyle characteristics, male partners should be implicated in lifestyle interventions already indicated for their spouse.

Disruption of O-GlcNAc homeostasis during mammalian oocyte meiotic maturation impacts fertilization

Meiotic maturation and fertilization are metabolically demanding processes, and thus the mammalian oocyte is highly susceptible to changes in nutrient availability. O-GlcNAcylation-the addition of a single sugar residue (O-linked β-N-acetylglucosamine) on proteins-is a posttranslational modification that acts as a cellular nutrient sensor and likely modulates the function of oocyte proteins. O-GlcNAcylation is mediated by O-GlcNAc transferase (OGT), which adds O-GlcNAc onto proteins, and O-GlcNAcase (OGA), which removes it. Here we investigated O-GlcNAcylation dynamics in bovine and human oocytes during meiosis and determined the developmental sequelae of its perturbation. OGA, OGT, and multiple O-GlcNAcylated proteins were expressed in bovine cumulus oocyte complexes (COCs), and they were localized throughout the gamete but were also enriched at specific subcellular sites. O-GlcNAcylated proteins were concentrated at the nuclear envelope at prophase I, OGA at the cortex throughout meiosis, and OGT at the meiotic spindles. These expression patterns were evolutionarily conserved in human oocytes. To examine O-GlcNAc function, we disrupted O-GlcNAc cycling during meiotic maturation in bovine COCs using Thiamet-G (TMG), a highly selective OGA inhibitor. Although TMG resulted in a dramatic increase in O-GlcNAcylated substrates in both cumulus cells and the oocyte, there was no effect on cumulus expansion or meiotic progression. However, zygote development was significantly compromised following in vitro fertilization of COCs matured in TMG due to the effects on sperm penetration, sperm head decondensation, and pronuclear formation. Thus, proper O-GlcNAc homeostasis during meiotic maturation is important for fertilization and pronuclear stage development.

Women undergoing assisted fertilisation and high-intensity interval training: a pilot randomised controlled trial

OBJECTIVES

Overweight and obese women often seek assisted fertilisation. In the obese population, pregnancy rates are 30%-75% below that of normal weight women who undergo assisted fertilisation. We hypothesised that high-intensity interval training (HIT) would improve fertility by improving insulin sensitivity and thus affect the hypothalamic-pituitary-ovarian axis and ovarian androgen production. Our aim was to assess whether HIT prior to assisted fertilisation would increase pregnancy rate.

METHODS

Eighteen overweight and obese women (body mass index>25.0 kg/m2) were randomised to HIT (n=8) or usual care (control, n=10) before assisted fertilisation. HIT was undertaken three times weekly for 10 weeks; two sessions of 4×4 min HIT and one session of 10×1 min HIT. Primary outcome was ongoing pregnancy. Secondary outcomes included insulin sensitivity, reproductive hormones, oxygen uptake and body composition.

RESULTS

Four women got pregnant in both the HIT group (50%) and in the control group (44%), no between-group difference (p=0.6). Insulin sensitivity (glucose infusion rate) improved significantly after HIT, from 264.1 mg/m2/min (95% CI 193.9 to 334.4) at baseline to 324.7 mg/m2/min (95% CI 247.2 to 402.2) after 10 weeks (between-group difference, p=0.04). Fasting glucose, visceral fat, waist circumference and VO2peak were significantly improved in the group that undertook HIT.

CONCLUSIONS

HIT significantly improved insulin sensitivity, VO2peak and abdominal fat. Low statistical power makes it difficult to conclude on whether HIT prior to assisted fertilisation could increase pregnancy rate. Larger trials are needed to determine if improvements in insulin sensitivity are clinically relevant for assisted fertilisation success rates in this population.

Obesity alters phosphoramide mustard-induced ovarian DNA repair in mice

Phosphoramide mustard (PM) destroys rapidly dividing cells and activates the DNA double strand break marker, γH2AX, and DNA repair in rat granulosa cells and neonatal ovaries. The effects of PM exposure on DNA damage and activation of DNA damage repair in lean and obese female mice were investigated. Wild type (lean) non agouti (a/a) and KK.Cg-Ay/J heterozygote (obese) mice received sesame oil or PM (95%; 25 mg/kg; intraperitoneal injection). Obesity increased (P < 0.05) hepatic and spleen but decreased (P < 0.05) uterine weight. PM exposure reduced (P < 0.05) spleen weight regardless of body composition, however, decreased (P < 0.05) ovarian and hepatic weight were observed in the obese PM-exposed females. PM decreased (P < 0.05) primordial and primary follicle number in lean females. Obesity and PM increased (P < 0.05) γH2AX protein. DNA damage repair genes Prkdc, Parp1, and Rad51 mRNA were unaltered by obesity, however, Atm and Xrcc6 mRNA were increased (P < 0.05) while Brca1 was reduced (P < 0.05). Obesity reduced (P < 0.05) PRKDC, XRCC6 and but increased (P < 0.05) ATM protein. ATM, BRCA1 and RAD51 protein levels were increased (P < 0.05) by PM exposure in both lean and obese mice, while PM-induced increased (P < 0.05) XRCC6 and PARP1 were observed only in lean mice. Thus, PM induces ovarian DNA damage in vivo; obesity alters DNA repair response gene mRNA and protein level; the ovary activates DNA repair proteins in response to PM; but obesity compromises the ovarian PM response.

Progressive obesity alters ovarian insulin, phosphatidylinositol-3 kinase, and chemical metabolism signaling pathways and potentiates ovotoxicity induced by phosphoramide mustard in mice

Mechanisms underlying obesity-associated reproductive impairment are ill defined. Hyperinsulinemia is a metabolic perturbation often observed in obese subjects. Insulin activates phosphatidylinositol 3-kinase (PI3K) signaling, which regulates ovarian folliculogenesis, steroidogenesis, and xenobiotic metabolism. The impact of progressive obesity on ovarian genes encoding mRNA involved in insulin-mediated PI3K signaling and xenobiotic biotransformation [insulin receptor (Insr), insulin receptor substrate 1 (Irs1), 2 (Irs2), and 3 (Irs3); kit ligand (Kitlg), stem cell growth factor receptor (Kit), protein kinase B (AKT) alpha (Akt1), beta (Akt2), forkhead transcription factor (FOXO) subfamily 1 (Foxo1), and subfamily 3 (Foxo3a), microsomal epoxide hydrolase (Ephx1), cytochrome P450 family 2, subfamily E, polypeptide 1 (Cyp2e1), glutathione S-transferase (GST) class Pi (Gstp1) and class mu 1 (Gstm1)] was determined in normal wild-type nonagouti (a/a; lean) and lethal yellow mice (KK.CG-Ay/J; obese) at 6, 12, 18, or 24 weeks of age. At 6 weeks, ovaries from obese mice had increased (P < 0.05) Insr and Irs3 but decreased (P < 0.05) Kitlg, Foxo1, and Cyp2e1 mRNA levels. Interestingly, at 12 weeks, an increase (P < 0.05) in Kitlg and Kit mRNA, pIRS1Ser302, pAKTThr308, EPHX1, and GSTP1 protein level was observed due to obesity, while Cyp2e1 mRNA and protein were reduced. A phosphoramide mustard (PM) challenge increased (P < 0.05) ovarian EPHX1 protein abundance in lean but not obese females. In addition, lung tissue from PM-exposed animals had increased (P < 0.05) EPHX1 protein with no impact of obesity thereon. Taken together, progressive obesity affected ovarian signaling pathways potentially involved in obesity-associated reproductive disorders.

Influence of follicular fluid and cumulus cells on oocyte quality: clinical implications

An equilibrium needs to be established by the cellular and acellular components of the ovarian follicle if developmental competence is to be acquired by the oocyte. Both cumulus cells (CCs) and follicular fluid (FF) are critical determinants for oocyte quality. Understanding how CCs and FF influence oocyte quality in the presence of deleterious systemic or pelvic conditions may impact clinical decisions in the course of managing infertility. Given that the functional integrities of FF and CCs are susceptible to concurrent pathological conditions, it is important to understand how pathophysiological factors influence natural fertility and the outcomes of pregnancy arising from the use of assisted reproduction technologies (ARTs). Accordingly, this review discusses the roles of CCs and FF in ensuring oocyte competence and present new insights on pathological conditions that may interfere with oocyte quality by altering the intrafollicular environment.

Obesity as disruptor of the female fertility

Both obesity and overweight are increasing worldwide and have detrimental influences on several human body functions including the reproductive health. In particular, obese women undergo perturbations of the 'hypothalamic pituitary ovarian axis', and frequently suffer of menstrual dysfunction leading to anovulation and infertility. Besides the hormone disorders and subfertility that are common in the polycystic ovary syndrome (PCOS), in obesity the adipocytes act as endocrine organ. The adipose tissue indeed, releases a number of bioactive molecules, namely adipokines, that variably interact with multiple molecular pathways of insulin resistance, inflammation, hypertension, cardiovascular risk, coagulation, and oocyte differentiation and maturation. Moreover, endometrial implantation and other reproductive functions are affected in obese women with complications including delayed conceptions, increased miscarriage rate, reduced outcomes in assisted conception treatments.On the contrary, weight loss programs through lifestyle modification in obese women, have been proven to restore menstrual cyclicity and ovulation and improve the likelihood of conception.

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.

The Responses of Mouse Preimplantation Embryos to Leptin In Vitro in a Transgenerational Model for Obesity

The aim of the present study was to test the hypothesis that leptin can directly mediate the negative effect of maternal obesity on preimplantation embryos. As previously shown, maternal obesity retards early embryonic development in vivo and increases the incidence of apoptosis in blastocysts. When two-cell embryos isolated from control and obese mice were transferred to identical (leptin free) conditions in vitro, no differences in any growth or quality parameters were recorded, including apoptosis incidence in blastocysts. Embryos isolated from control mice responded to transfer to environments with a high concentration of leptin (10 ng/mL) with a significant increase in arrest at the first or subsequent cell cycle. However, the majority of non-arrested embryos developed into blastocysts, showing morphology comparable to those cultured in the leptin-free group. On the other hand, the exposure of embryos isolated from obese mice to high leptin concentration in vitro did not retard their development. Furthermore, these embryos developed into blastocysts, showing a lower incidence of apoptosis. In vivo-developed blastocysts recovered from obese mice showed elevated expression levels of the proapoptotic gene BAX and the insulin-responsive glucose transporter gene SLC2A4. In conclusion, elevated leptin levels have both positive and negative effects on preimplantation embryo development in vitro, a response that likely depends on the body condition of the embryo donor. Moreover, these results suggest that leptin acts as a survival factor rather than an apoptotic inductor in embryonic cells. Since no elevations in the expression of the leptin receptor gene (LEPR) or fat metabolism-associated genes (PLIN2, SLC27A4) were recorded in blastocysts recovered from obese mice, the role of leptin in mediating the effects of obesity on embryos at the peripheral level is likely lower than expected.

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

BACKGROUND

Obesity is associated with several fertility disorders. This prospective cohort study was designed to evaluate the effect of body mass index (BMI) (kg/m2) on oocyte diameter and treatment.

METHODS

Women undergoing in vitro fertilization (IVF) with intracytoplasmic sperm injection (ICSI) were enrolled in the study. They were divided into two groups according to BMI: obese (BMI > 30) and normal weight (BMI < 25). Mature oocytes were evaluated according to total diameter, zona pellucida, and oolema diameters.

RESULTS

A total of 387 oocytes were obtained from the 46 women who participated. Significantly more mature oocytes (M2) were retrieved from normal weight patients compare to obese women (15.1 ± 6.8 vs. 9.7 ± 3.9, respectively, P < 0.001). Oocytes from women in the obese group were significantly smaller than those in the normal weight group, including oocyte diameter (157.9 ± 7.9 vs. 164.3 ± 5.1 μm, P < 0.0001), oolema diameter (110.3 ± 4.5 vs. 113.5 ± 3.5 μm, P < 0.0001), and zona pellucida thickness (17.9 ± 2.6 vs. 19.0 ± 2.4 μm, P < 0.000), respectively. Multivariate logistic regression analysis, including oolema diameter, female age, BMI, number of M2 oocytes, and zona pellucida, was conducted to predict pregnancy. Small oolema diameter in obese patient adversely correlated with pregnancy. Larger oolema diameter was positively associated with the probability of pregnancy in the obese group as well as thinner zona pellucida.

CONCLUSION

Obesity is associated with smaller oocytes, which adversely affect fertility outcomes.

TRIAL REGISTRATION

NIH number NCT01672931.

Maternal Overweight Disrupts the Sexual Maturation of the Offspring

The aims of the present work were to study the effect of maternal overweight and obesity on the ovarian reserve, follicular development, and ovulation of the offspring and to assess whether this maternal condition alters oocyte integrity. To this end, female offspring from rats fed standard (OSD) or cafeteria (OCD) diet were used. Body weight, vaginal opening, and estrous cycle were recorded and ovaries were obtained on the day of the second estrus. In addition, ovarian weight, ovulation rate (measured by the number of oocytes within oviducts), follicular development (determined by histology), and oocyte integrity were examined. The OCD were divided into 2 groups: offspring from rats with 17% and 28% of overweight (OCD17 and OCD28, respectively). Both OCD groups showed higher body weight, but OCD28 also exhibited early vaginal opening and higher ovarian weight and glycemia at euthanasia compared with OSD. Both OCD17 and OCD28 had lower number of primordial and primary follicles, and only OCD28 exhibited lower number of antral follicles, all compared with OSD rats. In addition, both OCD17 and OCD28 had higher ovulation rate than controls, and OCD28 had lower number of healthy oocytes, which, in turn, exhibited morphological alterations such as larger perivitelline space and zona pellucida than those of control animals. These results suggest that maternal overweight may severely affect the reproductive ability of the offspring, likely as a result of altering the organogenesis.

Enriched endoplasmic reticulum-mitochondria interactions result in mitochondrial dysfunction and apoptosis in oocytes from obese mice

Background

Maternal obesity alters oocytes and subsequent fetal metabolism. An increasing number of studies have shown that the endoplasmic reticulums (ER) or mitochondria have important effects on oocyte quality, but there has been no study of the effect of mitochondria-associated ER membranes (MAMs) on oocyte quality. The present study was designed to assess whether the level of MAM and MAM-related proteins were different in oocytes from obese and control mice.

Results

First, oocytes from mice with high-fat-diet (HFD)-induced obesity had higher levels (either greater numbers or a higher proportion for the same numbers) of MAM than oocytes from control mice. The abundance of MAM-related proteins in oocytes from obese mice was significantly greater at both the messenger RNA and protein levels, including inositol 1,4,5-trisphosphate receptor, type 1 (IP3R1), inositol 1,4,5-trisphosphate receptor, type 2 (IP3R2) and phosphofurin acidic cluster sorting protein 2 (PACS-2). Further, there was an increase in mitochondrial Ca²⁺ ([Ca²⁺]_m) which was associated with increased apoptosis and compromised cytoplasmic maturation in oocytes from obese mice. Down-regulation of MAM-related protein IP3R1 in oocytes from obese mice decreased [Ca²⁺]_m and apoptosis and improved cytoplasmic maturation but did not reduce the overall MAM level. However, down-regulating MAM-related protein PACS-2 in oocytes from obese mice did reduce the level of MAM and [Ca²⁺]_m, which decreased the rate of apoptosis and improved cytoplasmic maturation of oocytes from obese mice.

Conclusions

It is possible that enriched MAM could increase [Ca²⁺]_m, and this increase has been found to be associated with increased apoptosis and compromised cytoplasmic maturation in oocytes from obese mice. This finding suggests a novel therapeutic target for obesity-induced oocyte defects.

Electronic supplementary material

The online version of this article (doi:10.1186/s40104-017-0195-z) contains supplementary material, which is available to authorized users.

Impact of donor and recipient adiposity on placental and fetal growth in adolescent sheep

The influence of maternal obesity during oocyte development and its putative interaction with nutrient reserves at conception on pregnancy outcome were examined in an adolescent sheep model. Donor ewes were nutritionally managed to achieve contrasting adiposity (control (CD)/obese (ObD)) for 6 weeks prior to superovulation and inseminated by a non-obese sire. Morulae from 6 CD and 7 ObD were transferred in singleton into adolescent recipients of identical age but differing adiposity, classified as relatively fat or thin respectively. Thereafter, all were overnourished to promote rapid growth/adiposity (2 × 2 design, 13/14 pregnancies/group). A fifth recipient group of intermediate adiposity received embryos from another 5 CD, was offered a moderate intake to maintain adiposity throughout gestation and acted as controls for normal pregnancy outcome (optimally treated control (OTC), 19 pregnancies). Donor obesity did not influence ovulation, fertilisation or recovery rates or impact embryo morphology. Gestation length and colostrum yield were unaffected by donor or recipient adiposity and were reduced relative to OTC. Total fetal cotyledon and lamb birth weights were independent of initial donor adiposity but reduced in relatively thin vs relatively fat recipients and lower than those in the OTC group. In spite of high placental efficiency, the incidence of fetal growth restriction was greatest in the thin recipients. Thus, maternal adiposity at conception, but not pre-conception maternal obesity, modestly influences the feto-placental growth trajectory, whereas comparison with the OTC indicates that high gestational intakes to promote rapid maternal growth remain the dominant negative influence on pregnancy outcome in young adolescents. These findings inform dietary advice for pregnant adolescent girls.

Cardiovascular risk may be increased in women with unexplained infertility

Objective

Growing evidence suggests that increased cardiovascular disease (CVD) risk is associated with female infertility caused by conditions such as polycystic ovarian disease, obesity, thyroid dysfunction, and endometriosis. The aim of this study was to evaluate whether any relationship exists between CVD and unexplained infertility.

Methods

Sixty-five women with unexplained infertility and 65 fertile controls were enrolled in the study. CVD risk markers such as low-density lipoprotein (LDL), high-density lipoprotein (HDL), total cholesterol (TC), triglycerides (TG), insulin resistance (defined by the homeostasis model assessment ratio), and high-sensitivity C-reactive protein (hs-CRP) were assessed.

Results

TG, TC, LDL, and hs-CRP levels were higher and HDL levels were lower in patients with unexplained infertility than in fertile controls (p<0.05 for all). Positive associations were found between unexplained infertility and TG, TC, LDL, and hs-CRP levels, and a negative correlation was found for HDL (p<0.05 for all). Multivariate logistic regression analysis showed that TG, HDL, and hs-CRP were independent variables associated with unexplained infertility.

Conclusion

Our study showed that women with unexplained infertility had an atherogenic lipid profile and elevated hs-CRP levels, suggesting a higher risk of developing CVD in the future. Further studies with larger groups are needed to investigate the nature of this link.

Failure to launch: aberrant cumulus gene expression during oocyte in vitro maturation

In vitro maturation (IVM) offers significant benefits for human infertility treatment and animal breeding, but this potential is yet to be fully realised due to reduced oocyte developmental competence in comparison with in vivo matured oocytes. Cumulus cells occupy an essential position in determining oocyte developmental competence. Here we have examined the areas of deficient gene expression, as determined within microarrays primarily from cumulus cells of mouse COCs, but also other species, between in vivo matured and in vitro matured oocytes. By retrospectively analysing the literature, directed by focussing on downregulated genes, we provide an insight as to why the in vitro cumulus cells fail to support full oocyte potential and dissect molecular pathways that have important roles in oocyte competence. We conclude that the roles of epidermal growth factor signalling, the expanded extracellular matrix, cumulus cell metabolism and the immune system are critical deficiencies in cumulus cells of IVM COCs.

Using Mendelian randomization to determine causal effects of maternal pregnancy (intrauterine) exposures on offspring outcomes: Sources of bias and methods for assessing them

Mendelian randomization (MR), the use of genetic variants as instrumental variables (IVs) to test causal effects, is increasingly used in aetiological epidemiology. Few of the methodological developments in MR have considered the specific situation of using genetic IVs to test the causal effect of exposures in pregnant women on postnatal offspring outcomes. In this paper, we describe specific ways in which the IV assumptions might be violated when MR is used to test such intrauterine effects. We highlight the importance of considering the extent to which there is overlap between genetic variants in offspring that influence their outcome with genetic variants used as IVs in their mothers. Where there is overlap, and particularly if it generates a strong association of maternal genetic IVs with offspring outcome via the offspring genotype, the exclusion restriction assumption of IV analyses will be violated. We recommend a set of analyses that ought to be considered when MR is used to address research questions concerned with intrauterine effects on post-natal offspring outcomes, and provide details of how these can be undertaken and interpreted. These additional analyses include the use of genetic data from offspring and fathers, examining associations using maternal non-transmitted alleles, and using simulated data in sensitivity analyses (for which we provide code). We explore the extent to which new methods that have been developed for exploring violation of the exclusion restriction assumption in the two-sample setting (MR-Egger and median based methods) might be used when exploring intrauterine effects in one-sample MR. We provide a list of recommendations that researchers should use when applying MR to test the effects of intrauterine exposures on postnatal offspring outcomes and use an illustrative example with real data to demonstrate how our recommendations can be applied and subsequent results appropriately interpreted.