Maternal body mass index affects embryo morphokinetics: a time-lapse study

Granulosa cell metabolism at ovulation correlates with oocyte competence and is disrupted by obesity and aging

STUDY QUESTION

Is oocyte developmental competence associated with changes in granulosa cell (GC) metabolism?

SUMMARY ANSWER

GC metabolism is regulated by the LH surge, altered by obesity and reproductive aging, and, in women, specific metabolic profiles are associated with failed fertilization versus increased blastocyst development.

WHAT IS KNOWN ALREADY

The cellular environment in which an oocyte matures is critical to its future developmental competence. Metabolism is emerging as a potentially important factor; however, relative energy production profiles between GCs and cumulus cells and their use of differential substrates under normal in vivo ovulatory conditions are not well understood.

STUDY DESIGN, SIZE, DURATION

This study identified metabolic and substrate utilization profiles within ovarian cells in response to the LH surge, using mouse models and GCs of women undergoing gonadotropin-induced oocyte aspiration followed by IVF/ICSI.

PARTICIPANTS/MATERIALS, SETTING, METHODS

To comprehensively assess follicular energy metabolism, we used real-time metabolic analysis (Seahorse XFe96) to map energy metabolism dynamics (mitochondrial respiration, glycolysis, and fatty acid oxidation) in mouse GCs and cumulus-oocyte complexes (COCs) across a detailed time course in the lead up to ovulation. In parallel, the metabolic profile of GCs was measured in a cohort of 85 women undergoing IVF/ICSI (n = 21 with normal ovarian function; n = 64 with ovarian infertility) and correlated with clinical parameters and cycle outcomes.

MAIN RESULTS AND THE ROLE OF CHANCE

Our study reveals dynamic changes in GC energy metabolism in response to ovulatory LH, with mitochondrial respiration and glycolysis differentially affected by obesity versus aging, in both mice and women. High respiration in GCs is associated with failed fertilization (P < 0.05) in a subset of women, while glycolytic reserve and mitochondrial ATP production are correlated with on-time development at Day 3 (P < 0.05) and blastocyst formation (P < 0.01) respectively. These data provide new insights into the cellular mechanisms of infertility, by uncovering significant associations between metabolism within the ovarian follicle and oocyte developmental competence.

LIMITATIONS, REASONS FOR CAUTION

A larger prospective study is needed before the metabolic markers that were positively and negatively associated with oocyte quality can be used clinically to predict embryo outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

This study offers new insights into the importance of GC metabolism for subsequent embryonic development and highlights the potential for therapeutic strategies focused on optimizing mitochondrial metabolism to support embryonic development.

STUDY FUNDING/COMPETING INTEREST(S)

National Health and Medical Research Council (Australia). The authors have no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

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

STUDY QUESTION

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

SUMMARY ANSWER

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

WHAT IS KNOWN ALREADY

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

STUDY DESIGN, SIZE, DURATION

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

PARTICIPANTS/MATERIALS, SETTING, METHODS

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

MAIN RESULTS AND THE ROLE OF CHANCE

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

LIMITATIONS, REASONS FOR CAUTION

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

WIDER IMPLICATIONS OF THE FINDINGS

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

STUDY FUNDING/COMPETING INTEREST(S)

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

TRIAL REGISTRATION NUMBER

N/A.

The impact of oocyte central granularity on ICSI practice: developmental competence of dysmorphic and morphologically normal companion oocytes

PURPOSE

To assess the effects of oocyte central granularity and its underlying endocrine environment on developmental competence of dysmorphic and morphologically normal oocytes.

METHODS

Retrospective cohort study including 1,082 patients undergoing autologous ICSI cycles. Of these, 211 patients provided 602 oocytes with central granularity (CG) and 427 morphologically normal cycle companion oocytes (NCG). The remaining 871 patients provided only morphologically normal oocytes in cycles not yielding dysmorphic oocytes (N). Patient profile associated with CG was characterized, and fertilization rates, early morphokinetics and live birth rates were compared between N, CG and NCG groups. Patient characteristics associated with implantation and delivery performance of CG-derived embryos were assessed.

RESULTS

CG was associated with higher maternal age, basal FSH concentrations and total FSH dose, but with lower circulating AMH (p ≤ 0.035). Fertilization rates were reduced and early morphokinetic parameters were delayed in CG (p < 0.025) and NCG (p < 0.05) groups as compared to the N group. Embryos derived from CG oocytes achieved a markedly lower live birth rate (14.9%) as compared to those derived from NCG (36.8%; p = 0.03) and N oocytes (29.8%; p = 0.002). The negative relationship between CG and live birth was confirmed by a multivariate analysis controlling for potential confounders (OR:2.59, IC:1.27-5.31; P = 0.009). Implantation and delivery rates following transfers of CG-derived embryos were inversely associated with maternal age.

CONCLUSION

CG oocytes, but not their morphologically normal cycle companions, have severely compromised developmental competence. Maternal age should be a key parameter in deciding whether or not to utilize CG oocytes in ICSI cycles.

Maternal body mass index is not associated with assisted reproductive technology outcomes

The effects of body mass index (BMI) on assisted reproductive technology (ART) outcomes such as ovarian dysfunction, poor ovum quality, and endometrial dysfunction have been studied; however, many aspects remain controversial. Therefore, we retrospectively investigated the relationship between BMI and ART outcomes. For 14,605 oocyte retrieval cycles at our hospital between January 2016 and December 2020, BMI was divided into five groups (< 18.5, 18.5-20.0, 20.0-22.5, 22.5-25.0, ≥ 25 kg/m2) and measured before oocyte retrieval. The normal fertilization and high-grade blastocyst rates were compared. In addition, in the 7,122 frozen-thawed embryo transfers (FET) with highest-grade embryos, the clinical pregnancy, miscarriage, and live birth rates were investigated in the five BMI groups. Multiple regression analysis on normal fertilization and high-grade blastocyst rates revealed no statistically significant differences. Furthermore, after propensity score matching on FET, there was no significant difference in clinical pregnancy, miscarriage, and live birth rates in the BMI groups. BMI is a risk factor for complications during pregnancy; however, it does not affect ART outcomes. Therefore, we believe weight guidance should be provided to women with obesity at the start of infertility treatment, but treatment should not be delayed.

Associations between obesity, smoking behaviors, reproductive traits and spontaneous abortion: a univariable and multivariable Mendelian randomization study

Background

The correlation between potential risk factors such as obesity (leg fat percentage (left), arm fat percentage (left), waist circumference, body fat percentage, trunk fat percentage), smoking behaviors (past tobacco smoking, smoking initiation, smoking/smokers in household, current tobacco smoking) and reproductive traits (age first had sexual intercourse (AFS), age at menarche (AAM), and age at first birth (AFB)) have been linked to the occurrence of spontaneous abortion (SA). However, the causal associations between these factors and SA remain unclear.

Methods

We conducted univariable and multivariable Mendelian randomization (MR) analyses to evaluate the associations of obesity, smoking behavior and reproductive traits with SA. To select appropriate genetic instruments, we considered those that had reached the genome-wide significance level (P < 5 × 10-8) in their corresponding genome-wide association studies (GWAS) involving a large number of individuals (ranging from 29,346 to 1,232,091). SA was obtained from the FinnGen consortium, which provided summary-level data for 15,073 SA cases and 135,962 non-cases.

Results

Assessed individually using MR, the odds ratios (ORs) of SA were 0.728 (P = 4.3608×10-8), 1.063 (P = 0.0321), 0.926 (P = 9.4205×10-4), 1.141 (P = 7.9882×10-3), 5.154 (P = 0.0420), 1.220 (P = 0.0350), 1.228 (P = 0.0117), 0.795 (P = 0.0056), 1.126 (P = 0.0318), for one standard deviation (SD) increase in AFS, AAM, AFB, smoking initiation, smoking/smokers in household, arm fat percentage (left), leg fat percentage (left), waist circumference and body fat percentage, 0.925 (P = 0.4158) and 1.075 (P = 0.1479) for one SD increase in past tobacco smoking, trunk fat percentage for one SD increase in SA. In multivariable MR (MVMR), only AFS (OR = 0.802; P = 0.0250), smoking initiation (OR = 1.472, P = 0.0258), waist circumference (OR = 0.813, P = 0.0220) and leg fat percentage (left) (OR = 4.446, P = 0.043) retained a robust effect.

Conclusion

Smoking behaviors, reproductive traits and obesity-related anthropometric indicators are potential causal factors for SA. Higher leg fat percentage; smoking initiation; and lower waist circumference and AFS may increase the risk of SA. Understanding the causal relationship for SA may provide more information for SA intervention and prevention strategies.

A comparison of the morphokinetic profiles of embryos developed from vitrified versus fresh oocytes

RESEARCH QUESTION

Do morphokinetic profiles and treatment outcomes differ between embryos developed from vitrified or fresh oocytes?

DESIGN

Retrospective multicentre analysis using data from eight CARE Fertility clinics across the UK between 2012 and 2019. Patients receiving treatment using embryos developed from vitrified oocytes (n = 118 women, n = 748 oocytes), providing 557 zygotes during this time period, were recruited and matched with patients undergoing treatment with embryos developed from fresh oocytes (n = 123 women, n = 1110 oocytes), providing 539 zygotes in the same time frame. Time-lapse microscopy was used to assess morphokinetic profiles, including early cleavage divisions (2- through to 8-cell), post-cleavage stages including time to start of compaction, time to morula, time to start of blastulation and time to full blastocyst. Duration of key stages such as the compaction stage were also calculated. Treatment outcomes were compared between the two groups (live birth rate, clinical pregnancy rate and implantation rate).

RESULTS

A significant delay of 2-3 h across all early cleavage divisions (2- through to 8-cell) and time to start of compaction occurred in the vitrified group versus fresh controls (all P ≤ 0.01). The compaction stage was significantly shorter in vitrified oocytes (19.02 ± 0.5 h) compared with fresh controls (22.45 ± 0.6 h, P < 0.001). There was no difference in the time that fresh and vitrified embryos reached the blastocyst stage (108.03 ± 0.7 versus 107.78 ± 0.6 h). There was no significant difference in treatment outcomes between the two groups.

CONCLUSION

Vitrification is a useful technique for extending female fertility with no effects on IVF treatment outcome.

Oocyte degeneration in a cohort adversely affects clinical outcomes in conventional IVF cycles: a propensity score matching study

Background

Oocyte degeneration was mostly described in intracytoplasmic sperm injection (ICSI) cycles; there is no report showing the relationship between oocyte degeneration and clinical outcomes in conventional in vitro fertilization (IVF) cycles. This retrospective study using the propensity score (PS) matching method aimed to explore whether the presence of oocyte degeneration in conventional IVF cycles would affect the sibling embryo development potential and clinical outcomes.

Methods

Patients with at least one oocyte degenerated after short-term insemination and stripping were defined as the degeneration (DEG) group, while patients with no oocyte degenerated were defined as the non-degeneration (NONDEG) group. The PS matching method was used to control for potential confounding factors, and a multivariate logistic regression analysis was made to evaluate whether the presence of oocyte degeneration would affect the cumulative live birth rate (CLBR).

Results

After PS matching, basic characteristics were similar between the two groups, oocyte yield was significantly higher in the DEG group than the NON-DEG group (P < 0.05), mature oocyte number, 2 pronuclear (2PN) embryo number, 2PN embryo clearage rate, "slow" embryo number, "accelerated" embryo number, rate of cycles with total day 3 embryo extended culture, number of frozen embryo transfer (FET) cycles, transferred embryo stage, transferred embryo number, and live birth rate in fresh embryo transfer cycles were all similar between the two groups (P > 0.05), but the 2PN fertilization rate, available embryo number, high-quality embryo number, "normal" embryo number, frozen embryo number, blastocyst formation rate, and no available embryo cycle rate were all significantly lower in the DEG group than the NON-DEG group (P < 0.05). The cumulative live birth rate was also significantly lower in the DEG group than in the NON-DEG group (70.2% vs. 74.0%, P = 0.0019). Multivariate logistic regression analysis further demonstrated that the presence of oocyte degeneration in conventional IVF cycles adversely affects the CLBR both before (OR = 0.83, 95% CI: 0.75-0.92) and after (OR = 0.82, 95% CI: 0.72-0.93) PS matching.

Conclusion

Our findings together revealed that the presence of oocyte degeneration in a cohort of oocytes may adversely affect subsequent embryo development potential and clinical outcomes in conventional IVF cycles.

L-carnitine enhances developmental potential of bovine oocytes matured under high lipid concentrations in vitro

Maternal obesity elevates non-esterified fatty acids (NEFA) follicular concentrations. Bovine cumulus-oocyte complexes (COCs) matured in vitro under high NEFA have altered metabolism and reduced quality. Systemically, obesity promotes altered mitochondrial metabolism linked to L-carnitine insufficiency. We hypothesized that L-carnitine supplementation during IVM of bovine COCs in the presence of high NEFA would lessen the negative effects of exposure to excessive lipids on embryonic development and oxidative stress. COCs were collected from abattoir ovaries and matured in four groups: CON (control), LC (3 mM L-carnitine), HN (high NEFA: 200uM oleic, 150uM palmitic and 75uM stearic acid), and HNLC (HN and LC). Mature oocytes were assayed for aerobic and anaerobic metabolism utilizing oxygen and pH microsensors or fertilized in vitro (D0). Cleavage (D3) and blastocyst (D7, D8) rates were assessed. D3 embryos with ≥ 4 cells were stained for cytosolic and mitochondrial ROS. D8 blastocysts were assayed for gene transcript abundance of metabolic enzymes. Oocyte metabolism was not affected by IVM treatment. D3 formation of embryos with ≥ 4 cells were lower in LC or HN than CON or HNLC; blastocyst rates were greater for CON and lower for HN than LC and HNLC. D3 embryo mitochondrial and cytosolic ROS were reduced in HNLC when compared to other groups. IVM in HN altered blastocyst gene transcript abundance when compared to CON, but not LC or HNLC. In conclusion, supplementation with L-carnitine protects oocytes exposed to high NEFA during IVM and improves their developmental competence, suggesting that high lipid exposure may lead to L-carnitine insufficiency in bovine oocytes.

Risk Factors of Pregnancy Failure in Infertile Patients Undergoing Assisted Reproductive Technology

Background

Infertile couples need to use assisted reproductive technology (ART) to give birth. However, pregnancy failure after ART is not uncommon. At present, the results of studies on the causes of pregnancy failure after ART are inconsistent.

Methods

A retrospective cohort study involving 715 embryo transfer cycles was conducted at the Reproductive Medicine Center of Meizhou People's Hospital, from December 2015 to June 2022. According to the pregnancy, they were divided into clinical pregnancy group and pregnancy failure group. The relationship between demographic characteristics and pregnancy status between the two groups was analyzed.

Results

The pregnancy failure rate after ART was 49.7% (355/715). There were statistically significant distribution differences of maternal age, paternal age, COH protocols, and number of embryos transferred between clinical pregnancy and pregnancy failure groups (all P<0.01). Multiple logistic regression analysis shows that high maternal age (>35 years old vs ≤35 years old: OR 2.173, 95% CI: 1.386-3.407, P=0.001), and GnRH-a short protocol (GnRH-a short protocol vs GnRH-a long protocol: OR 2.139, 95% CI: 1.127-4.058, P=0.020) may increase risk of pregnancy failure in ART pregnancies, while two embryos transferred (two embryos transferred vs one embryo transferred: OR 0.563, 95% CI: 0.377-0.839, P=0.005) may reduce risk of pregnancy failure. In addition, high maternal age, GnRH antagonist protocol, and GnRH-a short protocol may increase risk of implantation failure, while two embryos transferred may reduce risk of implantation failure. And high maternal age may increase risk of biochemical pregnancy.

Conclusion

The risk of pregnancy failure increased in ART cycles with maternal age >35 years old and GnRH-a short protocol, while reduced with two embryos transferred.

Obesity-related alterations in protein expression in human follicular fluid from women undergoing in vitro fertilization

OBJECTIVE

To compare the proteomic composition of follicular fluid from women with normal weight vs. women with obesity but without a history of polycystic ovary syndrome or known ovarian dysfunction undergoing in vitro fertilization.

DESIGN

Cross-sectional.

SETTING

Academic medical center.

PATIENT(S)

Eight women with normal weight and 8 women with obesity undergoing in vitro fertilization and without a history of polycystic ovary syndrome, ovulatory dysfunction, diminished ovarian reserve, or known endometriosis were included in the analysis.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Proteomic assessment using liquid chromatography-mass spectrometry analysis.

RESULT(S)

The mean age of women with normal weight was similar to that of women with obesity (32.9 vs. 32.6 years, not significant). The mean body mass index of women with normal weight was 21.2 kg/m² compared with a body mass index of 37.1 kg/m² in women with obesity. A total of 1,174 proteins were identified with ≥2 peptides present. Twenty-five proteins were found to be significantly altered in the follicular fluid from women with obesity. Of these 25 proteins, 19 were up-regulated and 6 were down-regulated. Notably, C-reactive protein was 11-fold higher in the follicular fluid from women with obesity than in the follicular fluid from women with normal weight.

CONCLUSION(S)

Obesity is associated with dysregulation at the level of the follicle, including alterations in proteins related to inflammation and metabolism. These include proteins with emerging roles in energy homeostasis and follicular regulation.

The effect of maternal body mass index on embryo division timings in women undergoing in vitro fertilization

Objective

To measure the impact of maternal body mass index (BMI) on the morphokinetics of embryo development as monitored by a time-lapse system.

Design

A retrospective chart review of in vitro fertilization (IVF) cycles from September 2016 to January 2019.

Setting

Academic IVF practice.

Patients

Patients <age 38 years undergoing IVF with their own gametes.

Interventions

Not applicable.

Main outcome measures

The primary outcome was to compare embryo division timings between morbidly obese, obese, overweight, and normal-weight patients. A multilevel mixed effects model was performed to investigate the relationships between BMI categories and embryo division timings. Log or square transformation were used to improve fit.

Results

A total of 366 patients met inclusion criteria, yielding 4,475 embryos: 1,948 embryos from 162 normal-weight women (BMI 18.5-24.9), 1,242 embryos from 96 overweight women (BMI 25.0-29.9), 1,119 embryos from 91 obese women (BMI 30.0-39.9), and 166 embryos from 17 morbidly obese women (BMI ≥40). There were no differences in age, Antimüllerian hormone, or IVF cycle outcomes among the different BMI categories. When comparing embryo division timings based on BMI, controlling for covariates, embryos from obese patients had a shorter time to division to 2 cell embryo (T2) than normal-weight patients. When analyzing BMI as a continuous variable, there was no significant relationship between BMI and embryo division timing.

Conclusions

Early embryo divisions were accelerated in only certain categories of obesity. This suggests a more complex mechanism for the effect of obesity on embryo development that may not be perceptible through the assessment of cell division timing events.

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.

Maternal underweight does not adversely affect the outcomes of IVF/ICSI and frozen embryo transfer cycles or early embryo development

OBJECTIVE

To compare assisted reproductive technology (ART) outcomes and preimplantation embryo development between underweight and normal-weight women.

METHODS

This retrospective cohort study included 26 underweight women (body mass index [BMI] < 18.50 kg/m²) and 104 normal-weight women (BMI >20 and <24.9 kg/m²) who underwent a total of 204 in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles and 358 fresh/frozen embryo transfers (ET) in our institution between January 2016 and December 2018. Statistical analyses compared selected ART outcomes (ovarian stimulation, fertilization, and pregnancy) between both weight groups. Morphokinetic and morphological parameters were also compared between 346 and 1467 embryos of underweight and normal-weight women, respectively.

RESULTS

The mean ± standard deviation age of the underweight and normal-weight women was similar (31.6 ± 4.17 vs 32.4 ± 3.59 years; p = .323). There were no differences in the peak estradiol levels, the number of retrieved oocytes, the number of metaphase II oocytes, and the oocyte maturity rates between the two groups. The IVF/ICSI fertilization rates and the number of embryos suitable for transfer or cryopreservation were similar for both groups. All morphokinetic parameters that were evaluated by means of time-lapse imaging as well as the morphological characteristics were comparable between low and normal BMI categories. There were no significant differences in pregnancy achievement, clinical pregnancy, live births, and miscarriage rates between the suboptimal and optimal weight women.

CONCLUSION

Underweight status has no adverse impacts on the outcomes of IVF/ICSI with either fresh or frozen ET or on preimplantation embryo development and quality.

BMI and miscarriage after IVF

PURPOSE OF REVIEW

To summarize recent findings related to the risk of miscarriage in women with elevated BMI undergoing IVF, and the mechanisms involved in said risk.

RECENT FINDINGS

Miscarriage rates are increased in overweight and obese women in both natural and assisted reproduction. Oocyte and embryo quality assessed according to classic morphological static parameters does not seem to be affected by excessive female body weight. Despite the initial lack of consensus between studies regarding embryo morphokinetics in obese women, blastocyst formation and quality have recently been shown to be similar across BMI groups, even in the case of euploid embryos. However, some metabolomic differences have been described in oocytes and embryos from obese women, thus pointing to a functional alteration. In women with elevated BMI, the percentage of aneuploid embryos is similar to that of normal weight women, and rates of miscarriage are higher, despite the transfer of euploid embryos. Therefore, the origin of the increased pregnancy loss rate after IVF in these women may be related to metabolomic, epigenetic or mitochondrial oocyte and embryo disturbances, or to the abnormal endocrine, metabolic and inflammatory uterine environment induced by obesity, which seems to be also responsible for other numerous complications during pregnancy and the in-utero fetal programming of postnatal diseases. A displacement of the window of implantation in obese women undergoing artificial endometrial preparation has recently been described and may be related to the poorer embryo implantation rates and increased risk of miscarriage observed following fresh and frozen embryo transfers with autologous oocytes, and with donated ova in recipients with extremely high BMI.

SUMMARY

Female obesity is related to poorer outcome in natural and assisted conception, including an increased risk of miscarriage. Embryo morphology, assessed by conventional methods or by morphokinetics, does not seem to be affected by excess weight, with similar blastocyst formation and quality than normal weight women reported in IVF cycles. Embryo aneuploidy is not increased, and higher miscarriages rates are seen after euploid embryo transfer in obese women. Disturbances of the uterus or its environment induced by female obesity seem to be the most likely cause of the increased risk of miscarriage, although metabolomic, epigenetic or mitochondrial oocyte and embryo dysfunction cannot be ruled out as cannot congenital anomalies. In the context of all the above, weight reduction before pregnancy should be advised in obese women trying to become pregnant.

Oocyte quality in assisted reproduction techniques

The metaphase II (MII) oocyte is the mature female gamete, produced from a complex maturation process called oogenesis that starts in the first weeks of embryogenesis in the female embryo tract, continues during puberty, and is completed at fertilization with the spermatozoon. Oogenesis is closely related to folliculogenesis. In assisted reproduction techniques, oocytes are retrieved in cumulus-oocyte complexes after ovarian stimulation. Before being used for in vitro fertilization or cryopreservation, the metaphase (MII) oocytes can be classified according to different morphological traits and by the presence/absence of the meiotic spindle. Except for a few and rare morphological characteristics that make the oocyte discarded, none of the morphological characteristics is predictive of oocyte competence in giving a viable embryo. On the other side, specific key performance indicators based on MII oocytes test the efficacy of in vitro treatments. Molecular, cellular, or genetic abnormalities in the oocytes have observable consequences on the embryo development dynamics and its genetic content. Besides what can be seen in vitro, several intrinsic and extrinsic factors related to the patient are responsible for the oocyte quality. The clinician and the patient herself must be aware of these factors to preserve the reproductive functions as much as possible. In the present review, we have revised oogenesis and the role of mature oocytes in supporting the fertilization process and early embryo development; we have also listed the oocyte morphological traits and key performance indicators related to the oocyte quality and studied the intrinsic and extrinsic factors that irreversibly impact female fertility.

Body Size, Fertility, and Reproductive Justice: Examining the Complex Interplay between BMI, Reproductive Health, and Access to Care

The relationship between obesity and reproduction is highly complex. While there are clear obstetrical and fertility risks associated with elevated BMI, it is less clear how weight loss impacts these outcomes. Increasingly, patients considered obese according to BMI are being denied access to fertility care, thus leaving them without treatment options for their disease (infertility). Notably, BMI cutoffs disproportionately affect historically marginalized populations in the United States and people of lower socioeconomic status (SES). This paper uses a reproductive justice framework to discuss access to reproductive healthcare based on BMI. In doing so, we connect obesity to larger systems of structural inequalities. We conclude that rather than strict BMI cutoffs, a more holistically patient-centered approach is appropriate taking into account the overall health of the individual, available scientific data, clinical capabilities, and the patient’s value system. This will ultimately make reproductive medicine more accessible to all patients.

Embryonic Development in Relation to Maternal Obesity Does Not Affect Pregnancy Outcomes in FET Cycles

This retrospective cohort study examined the effect of maternal BMI on embryo morphokinetics using a time-lapse incubator (TLI) and evaluated the effect on outcomes of frozen embryo transfer (FET) cycles. The study included 641 women who underwent FET of a total of 2553 embryos from January 2017 to August 2019. The women were divided into four groups according to BMI: underweight (<18.5 kg/m2), normal weight (18.5−24.99 kg/m2), overweight (25.0−29.99 kg/m2), and obese (≥30 kg/m2). Embryos were transferred on day 3 or 5, and their development was monitored using a TLI. We found that oocytes from obese patients were slower in the extraction of the second polar body (tPB2) after fertilization and the two pronucleus stage appeared later compared to normal-weight women. The time to fading of the pronucleus (tPNf), t2, and t4 were comparable between the four groups. Oocytes from underweight and overweight women had significantly faster cleavage at t3 and t5−t8 compared to normal weight. We did not find any significant difference in pregnancy rate, clinical pregnancy rate, or miscarriage rate among groups. In conclusion, embryos from normal-weight patients had slower cleavage rates compared to obese patients, while embryo quality was similar between BMI groups. The cycle outcomes demonstrated comparable pregnancy rates among the BMI groups.

Long-term Hyperandrogenemia and/or Western-style Diet in Rhesus Macaque Females Impairs Preimplantation Embryogenesis

Hyperandrogenemia and obesity are common in women with polycystic ovary syndrome, but it is currently unclear how each alone or in combination contribute to reproductive dysfunction and female infertility. To distinguish the individual and combined effects of hyperandrogenemia and an obesogenic diet on ovarian function, prepubertal female rhesus macaques received a standard control (C) diet, testosterone (T) implants, an obesogenic Western-style diet (WSD), or both (T + WSD). After 5 to 6 years of treatment, the females underwent metabolic assessments and controlled ovarian stimulations. Follicular fluid (FF) was collected for steroid and cytokine analysis and the oocytes fertilized in vitro. Although the T + WSD females exhibited higher insulin resistance compared to the controls, there were no significant differences in metabolic parameters between treatments. Significantly higher concentrations of CXCL-10 were detected in the FF from the T group, but no significant differences in intrafollicular steroid levels were observed. Immunostaining of cleavage-stage embryos revealed multiple nuclear abnormalities in the T, WSD, and T + WSD groups. Single-cell DNA sequencing showed that while C embryos contained primarily euploid blastomeres, most cells in the other treatment groups were aneuploid. Despite yielding a higher number of mature oocytes, T + WSD treatment resulted in significantly reduced blastocyst formation rates compared to the T group. RNA sequencing analysis of individual blastocysts showed differential expression of genes involved in critical implantation processes between the C group and other treatments. Collectively, we show that long-term WSD consumption reduces the capacity of fertilized oocytes to develop into blastocysts and that the addition of T further impacts gene expression and embryogenesis.

Abnormal BMI in Male and/or Female Partners Are Deleterious for Embryonic Development and Pregnancy Outcome During ART Process: A Retrospective Study

OBJECTIVE

To investigate the effect of BMI in male and/or female partners on embryo development and clinical pregnancy outcome during ART.

METHODS

Data of 11,130 cycles between January 2018 and December 2020 were retrospectively analyzed. They were divided into Group A, B, C, and D based on couples' BMI values, also were divided into Group I, II, III and IV in IVF cycles and Group i, ii, iii, and iv in ICSI cycles. After grouping, inter-group indicators comparisons and logistic regression analysis were performed.

RESULTS

In IVF cycles, CPR in Group I and Group III were higher than Group IV. In Group III, it was higher than Group II. The AR in Group IV was higher, but the LBR was lower than Group I, Group II, and Group III. Logistic regression analysis results suggested that AR in Group IV was higher than that in Group I in IVF cycles, whereas LBR was lower.In ICSI cycles, high-quality embryo rate in Group i and Group ii were both higher than that in Group iii and Group iv. The CPR in Group i was higher than Group ii and Group iv, and in Group iii was higher than Group ii and Group iv. The AR in Group i was lower than Group iii and Group iv, and AR in Group ii was lower than Group iv. LBR, in Group I it was higher than Group ii, Group iii, and Group iv. Logistic regression analysis results suggested CPR in Group ii was significantly lower than that in Group i. AR in Group iii was considerably higher than that in Group i. LBR in Group ii and Group iv were significantly lower than that in Group i.

CONCLUSION

Female higher BMI was not conducive to the formation of high-quality embryos in ICSI cycle. Female and/or male BMI affected AR and LBR more than CPR not only in IVF cycles, but also in ICSI cycles.

Female obesity and infertility: outcomes and regulatory guidance

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

Analysis and quantification of female and male contributions to the first stages of embryonic kinetics: study from a time-lapse system

PURPOSE

The few studies that examined the effect of male and/or female features on early embryo development, notably using the time-lapse system (TL), reported conflicting results. This can be explained by the small number of studies using an adapted model.

METHODS

We used two original designs to study the female and male effects on embryo development: (1) based on embryos from donor oocytes (TL-DO), and (2) from donor sperm (TL-DS). Firstly, we analyzed the female and male similarities using an ad hoc intraclass correlation coefficient (ICC), then we completed the analysis with a multivariable model to assess the association between both male and female factors, and early embryo kinetics. A total of 572 mature oocytes (TL-DO: 293; TL-DS: 279), fertilized by intracytoplasmic sperm injection (ICSI) and incubated in a TL (Embryoscope®) were included from March 2013 to April 2019; 429 fertilized oocytes (TL-DO: 212; TL-DS: 217) were assessed. The timings of the first 48 h have been analyzed.

RESULTS

The similarities in the timings thought to be related to the female component were significant: (ICC in both DO-DS designs respectively: tPB2: 9-18%; tPNa: 16-21%; tPNf: 40-26%; t2: 38-24%; t3: 15-20%; t4: 21-32%). Comparatively, those related to male were lower. Surprisingly after multivariable analyses, no intrinsic female factors were clearly identified. However, in TL-DO design, oligozoospermia was associated with a tendency to longer timings, notably for tPB2 (p = 0.026).

CONCLUSION

This study quantifies the role of the oocyte in the first embryo cleavages, but without identified specific female factors. However, it also highlights that sperm may have an early embryonic effect.

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.

Blastocyst formation is similar in obese and normal weight women: a morphokinetic study

STUDY QUESTION

Does the embryo cleavage pattern and rate of blastocyst formation differ between normal weight and obese women undergoing IVF?

SUMMARY ANSWER

Embryo morphokinetic development, final blastocyst formation rate and blastocyst morphology do not differ between obese and normal weight women.

WHAT IS KNOWN ALREADY

Female obesity has been related to impaired IVF outcomes. Although the mechanisms responsible for this detrimental effect are thought to include impaired oocyte and embryo quality and reduced endometrial receptivity, they are yet to be confirmed. Embryo quality has been commonly assessed using static morphological criteria. Only three studies have analysed the progress of embryos up to the blastocyst stage in women with elevated BMI, but they have used small samples of patients or have obtained contradictory results.

STUDY DESIGN, SIZE, DURATION

This retrospective, cohort study, was performed from January 2016 to May 2020. A total of 3316 ICSI cycles from 2822 women were included, of which 1251 cycles were part of a preimplantation genetic testing programme. In total, 17 848 embryos were analysed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study reports on the IVF cycles of infertile women, with a known BMI, who underwent ICSI and whose embryos were grown until the fifth/sixth day of development in a time-lapse system. Patients were grouped as follows. Underweight was defined as a BMI <18.5 kg/m2; normal weight was a BMI of 18.5-24.9 kg/m2; overweight was a BMI of 25-29.9 kg/m2; and obesity was a BMI of ≥30 kg/m2. Embryo development was assessed on an external computer with analysis software.

MAIN RESULTS AND THE ROLE OF CHANCE

Despite an initial slower pattern of embryo development, the blastocyst formation rate on day 5 or on day 5 plus day 6 did not differ in obese women with respect to the other three BMI groups. Moreover, based on the evaluation of inner cell mass and the trophectoderm on both days of blastocyst development, embryo quality was similar across the BMI groups, as were the pattern of development and arrest up to blastocyst formation and the distribution of the categories of full, expanded and hatching blastocysts.

LIMITATIONS, REASONS FOR CAUTION

Limitations include the retrospective analysis of data, the use of BMI as the only parameter to define normal/abnormal female body weight, and the lack of complete information about clinical outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

Blastocyst formation and embryo morphokinetics are not affected by female obesity, and the poorer IVF outcomes described for such women are probably due to deficient endometrial receptivity. The role of endometrial progesterone exposure on the day of embryo transfer should be analysed in future studies as a possible determining factor.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used and there are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

A higher preconceptional paternal body mass index influences fertilization rate and preimplantation embryo development

Background

Obesity is a worldwide problem affecting the health of millions of people throughout the life course. Studies reveal that obesity impairs sperm parameters and epigenetics, potentially influencing embryonic development.

Objective

To investigate the association between preconceptional paternal body mass index (BMI) and embryo morphokinetics using a time‐lapse incubator and in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) outcomes.

Materials and methods

Participants were recruited from a tertiary hospital in this prospective periconceptional cohort study. A total of 211 men were included: 86 with normal weight (BMI < 25.0), 94 overweight (BMI 25–29.9), and 41 obese (BMI ≥ 30). These men were part of a couple that underwent IVF/ICSI treatment with ejaculated sperm after which 757 embryos were cultured in a time‐lapse incubator. The main outcome parameters consisted of fertilization rate, embryo developmental morphokinetics, embryo quality assessed by a time‐lapse prediction algorithm (KIDScore), and live birth rate.

Results

A higher paternal BMI was associated with faster development of the preimplantation embryo, especially during the first cleavage divisions (t2: −0.11 h (p = 0.05) and t3: −0.19 h (p = 0.01)). Embryo quality using the KIDScore was not altered. The linear regression analysis, after adjustment for confounders (paternal age, ethnicity, smoking, alcohol use, education, total motile sperm count, and maternal age and BMI), showed an inverse association between paternal BMI and fertilization rate (effect estimate: −0.01 (p = 0.002)), but not with the live birth rate.

Discussion and conclusion

Our data demonstrate that a higher preconceptional paternal BMI is associated with a reduced fertilization rate in IVF/ICSI treatment. Our findings underline the importance of a healthy paternal weight during the preconception period.

Obesity and reproduction: a committee opinion

The purpose of this American Society for Reproductive Medicine Practice Committee report is to provide clinicians with principles and strategies for the evaluation and treatment of couples with infertility associated with obesity. This revised document replaces the Practice Committee document titled "Obesity and reproduction: an educational bulletin" last published in 2015 (Fertil Steril 2015;104:1116-26).

Higher preconceptional maternal body mass index is associated with faster early preimplantation embryonic development: the Rotterdam periconception cohort

BACKGROUND

Overweight and obesity affect millions of people globally, which has also serious implications for reproduction. For example, treatment outcomes after in vitro fertilisation (IVF) are worse in women with a high body mass index (BMI). However, the impact of maternal BMI on embryo quality is inconclusive. Our main aim is to study associations between preconceptional maternal BMI and morphokinetic parameters of preimplantation embryos and predicted implantation potential. In addition, associations with clinical IVF outcomes are investigated.

METHODS

From a tertiary hospital, 268 women undergoing IVF or IVF with intracytoplasmic sperm injection (ICSI) were included; 143 normal weight, 79 overweight and 46 obese women. The embryos of these women were cultured in the EmbryoScope, a time-lapse incubator. The morphokinetic parameters of preimplantation embryos and predicted implantation potential, assessed by the KIDScore algorithm were longitudinally evaluated as primary and secondary outcomes, respectively. The tertiary outcomes included clinical outcomes, i.e., fertilization, implantation and live birth rate.

RESULTS

After adjustment for patient- and treatment-related factors, we demonstrated in 938 embryos that maternal BMI is negatively associated with the moment of pronuclear appearance (β_tPNa -0.070 h (95%CI -0.139, -0.001), p = 0.048), pronuclear fading (β_tPNf -0.091 h (95%CI -0.180, -0.003), p = 0.043 and the first cell cleavage (β_t2 -0.111 h (95%CI -0.205, -0.016), p = 0.022). Maternal BMI was not significantly associated with the KIDScore and tertiary clinical treatment outcomes. In embryos from couples with female or combined factor subfertility, the impact of maternal BMI was even larger (β_tPNf -0.170 h (95%CI -0.293, -0.047), p = 0.007; β_t2 -0.199 h (95%CI -0.330, -0.067), p = 0.003). Additionally, a detrimental impact of BMI per point increase was observed on the KIDScore (β -0.073 (se 0.028), p = 0.010).

CONCLUSIONS

Higher maternal BMI is associated with faster early preimplantation development. In couples with female or combined factor subfertility, a higher BMI is associated with a lower implantation potential as predicted by the KIDScore. Likely due to power issues, we did not observe an impact on clinical treatment outcomes. However, an effect of faster preimplantation development on post-implantation development is conceivable, especially since the impact of maternal BMI on pregnancy outcomes has been widely demonstrated.

Early and late paternal contribution to cell division of embryos in a time-lapse imaging incubation system

The objective of this study was to investigate the impact of male age, semen quality and days of ejaculatory abstinence on embryo morphokinetics. A total of 1,220 zygotes obtained from 139 couples in a private in vitro fertilisation centre were analysed. The timing of specific events from the point of insemination, such as timings to pronuclei appearance and fading, to two, three, four, five, six, seven and eight cells and to blastulation were recorded. Multivariate linear regression analysis was used to evaluate the influence of paternal factors on embryo morphokinetic events. Paternal age was positively correlated with delayed cell cleavage and blastulation, and negatively associated with implantation rate, and clinical pregnancy and live-birth chances. The ejaculatory abstinence was inversely correlated with the implantation rate. Inverse relationships were observed between semen parameters (sperm count, progressive sperm motility, total motile sperm count and morphology) and the timing of specific events during embryo development. Sperm morphology was also positively associated with implantation rate and pregnancy and live-birth chances. Increased paternal age and ejaculatory abstinence, and poor semen quality correlate with delayed cell cleavage and blastulation and negatively impact intracytoplasmic sperm injection outcomes.

Early embryo morphokinetics is a better predictor of post-ICSI live birth than embryo morphology: speed is more important than beauty at the cleavage stage

Given the importance of embryo developmental competence assessment in reproductive medicine and biology, the aim of this study was to compare the performance of fertilization and cleavage morphokinetics with embryo morphology to predict post-ICSI live birth. Data from embryos cultured in a time-lapse microscopy (TLM) incubator and with known live birth outcomes (LB: embryos achieving live birth, n = 168; NLB: embryos not achieving live birth, n = 1633) were used to generate receiver operating characteristic (ROC) curves based on morphokinetic or morphological scores, and the respective areas under the curve (AUC) were compared. The association between live birth and 12 combinations of four morphokinetic quality degrees (A-D) with three morphological quality degrees (A-C) was assessed using multivariate analysis. Morphokinetic parameters from tPNa to t8 were reached earlier in LB compared with NLB embryos. The ROC curve analysis indicated that morphokinetic information is more accurate than conventional morphology to predict live birth [AUC = 0.64 (95% CI 0.58-0.70) versus AUC = 0.58 (95% CI 0.51-0.65)]. The multivariate analysis was in line with AUCs, revealing that embryos with poor morphokinetics, independently of their morphology, provide lower live birth rates (P < 0.001). A considerable percentage of embryos with top morphology presented poor morphokinetics (20.10%), accompanied by a severely reduced live birth rate in comparison with embryos with top morphology and morphokinetics (P < 0.001). In conclusion, TLM-derived early morphokinetic parameters were more predictive of live-birth achievement following ICSI than conventional morphology.

Maternal age affects the relationship of basal FSH and anti-Müllerian hormone concentrations with post-ICSI/IVF live birth

RESEARCH QUESTION

Does the association of basal FSH and anti-Müllerian hormone (AMH) concentrations with post-IVF/intracytoplasmic sperm injection (ICSI) live birth change with maternal age?

DESIGN

A total of 2003 IVF/ICSI patients were stratified according to basal FSH/AMH in concordant favourable (CF; AMH >1 ng/ml and FSH ≤10 IU/l), concordant unfavourable (CU; AMH ≤1 ng/ml and FSH >10 IU/l), discordant with favourable AMH (DFA) and discordant with favourable FSH (DFF) groups, as well as according to age in pre-advanced maternal age (pre-AMA; <35), AMA-1 (≥35, ≤37), AMA-2 (>37, ≤40) and AMA-3 (>40). IVF/ICSI outcomes were compared among CF, CU, DFA and DFF groups, and the association of basal FSH and AMH concentrations with live birth was tested by univariate and multivariate analysis in total, pre-AMA and AMA groups, separately.

RESULTS

Different outcome patterns were observed in discordant AMH/FSH groups from different age categories; favourable basal FSH concentrations were associated with higher delivery rates in pre-AMA patients, but with lower delivery rates in AMA groups. Within pre-AMA patients, DFF patients presented higher delivery rates but lower oocyte yield compared with DFA patients. In the univariate analysis, favourable AMH (P < 0.02) and oocyte yield (P < 0.002) were positively associated with live birth in all AMA groups. The multivariate analysis revealed that favourable basal FSH, but not AMH or oocyte yield, is associated with live birth in pre-AMA patients independently of other variables (P = 0.012).

CONCLUSIONS

The relationship of basal FSH and AMH with IVF/ICSI success changes with maternal age; basal FSH better reflects clinical outcomes probably determined by oocyte quality in pre-AMA patients, while AMH better suits AMA patients.

An investigation into the effect of potential confounding patient and treatment parameters on human embryo morphokinetics

OBJECTIVE

To determine the effect of patient and treatment parameters on 19 embryo morphokinetic parameters using pronuclear fading as time zero.

DESIGN

Single-site, retrospective cohort analysis.

SETTING

Fertility treatment center.

PATIENTS(S)

Patients undergoing treatment between September 2014 and January 2016 (n = 639) whose embryos were cultured in the EmbryoScope for 6 days (n = 2,376).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Multiple regression analysis of body mass index; maternal age; infertility diagnosis; treatment type; suppression protocol on time to each cellular division (tn): t2, t3, t4, t5, t6, t7, t8, t9, time to start of compaction (tM), start of blastulation (tSB), full blastocyst (tB); and interval measurements: s2, s3, cc2, cc3, cc4, t9-tM, tM-tSB, and tSB-tB. Beta coefficients were analyzed to quantify any significant effects.

RESULT(S)

Embryos appeared to be subtly affected by patient and treatment parameters, exhibiting complex relationships between various morphokinetic parameters and specific patient and treatment factors, rather than a systemic effect.

CONCLUSION(S)

These findings outline the need for the consideration of confounding factors when assessing an embryo's ability to achieve implantation. Although morphokinetic parameters have been related to embryo viability, it is likely that this will vary depending on the embryo's origin.

The clinical use of time-lapse in human-assisted reproduction

A major challenge in the assisted reproduction laboratory is to set up reproducible and efficient criteria to identify the embryo with the highest developmental potential. Over the years, several methods have been used worldwide with this purpose. Initially, standard morphology assessment was the only available strategy. It is now universally recognized that besides being a very subjective embryo selection strategy, morphology evaluation alone has a very poor prognostic value. More recently, the availability of time-lapse incubators allowed a continuous monitoring of human embryo development. This technology has spread quickly and many fertility clinics over the world produced a remarkable amount of data. To date, however, a general consensus on which variables, or combination of variables, should play a central role in embryo selection is still lacking. Many confounding factors, concerning both patient features and clinical and biological procedures, have been observed to influence embryo development. In addition, several studies have reported unexpected positive outcomes, even in the presence of abnormal developmental criteria. While it does not seem that time-lapse technology is ready to entirely replace the more invasive preimplantation genetic testing in identifying the embryo with the highest implantation potential, it is certainly true that its application is rapidly growing, becoming progressively more accurate. Studies involving artificial intelligence and deep-learning models as well as combining morphokinetic with other non-invasive markers of embryo development, are currently ongoing, raising hopes for its successful applicability for clinical purpose in the near future. The present review mainly focuses on data published starting from the first decade of 2000, when time-lapse technology was introduced as a routine clinical practice in the infertility centers.

Mining of variables from embryo morphokinetics, blastocyst's morphology and patient parameters: an approach to predict the live birth in the assisted reproduction service

Based on growing demand for assisted reproduction technology, improved predictive models are required to optimize in vitro fertilization/intracytoplasmatic sperm injection strategies, prioritizing single embryo transfer. There are still several obstacles to overcome for the purpose of improving assisted reproductive success, such as intra- and inter-observer subjectivity in embryonic selection, high occurrence of multiple pregnancies, maternal and neonatal complications. Here, we compare studies that used several variables that impact the success of assisted reproduction, such as blastocyst morphology and morphokinetic aspects of embryo development as well as characteristics of the patients submitted to assisted reproduction, in order to predict embryo quality, implantation or live birth. Thereby, we emphasize the proposal of an artificial intelligence-based platform for a more objective method to predict live birth.

Effect of a Combination of Myo-Inositol, Alpha-Lipoic Acid, and Folic Acid on Oocyte Morphology and Embryo Morphokinetics in non-PCOS Overweight/Obese Patients Undergoing IVF: A Pilot, Prospective, Randomized Study

Herein we aimed at assessing whether Myo-Inositol (MI), Alpha–Lipoic acid (ALA), and Folic acid (FA) could improve oocyte quality and embryo development in non-PCOS overweight/obese women undergoing IVF. Three hundred and twenty-four mature oocytes were obtained from non-PCOS overweight/obese patients, randomized to receive either MI, ALA, and FA (MI + ALA + FA group, n = 155 oocytes) or FA alone (FA-only group, n = 169 oocytes). Oocytes were examined using Polarized Light Microscopy to assess morphological features of zona pellucida (ZP) and meiotic spindle (MS). One hundred and seventy-six embryos (n = 84 in the MI + ALA + FA group, n = 92 in the FA-only group) were assessed by conventional morphology on days 2 and 5, as well as using the Time-Lapse System morphokinetic analysis. A significantly higher ZP retardance, area, and thickness (p < 0.05), and a shorter MS axis (p < 0.05) were observed in the MI + ALA + FA group, suggesting a positive effect on oocyte quality. Conventional morphology evaluation on day 2 showed a higher mean embryo score in the MI + ALA + FA group, whereas embryo morphokinetic was comparable in the two groups. Overall, our data show a possible beneficial effect of the combination of MI, ALA, and FA on oocyte and embryo morphology, encouraging testing of this combination in adequately powered randomized trials to assess their impact of clinical IVF results.

Faster fertilization and cleavage kinetics reflect competence to achieve a live birth after intracytoplasmic sperm injection, but this association fades with maternal age

OBJECTIVE

To assess the relationship of early developmental kinetics with competence to provide a live birth and the impact of maternal age in this context.

DESIGN

Retrospective cohort study including 4,915 embryos, of which 1,390 were transferred and provided a clinical outcome paired with morphokinetic data; 168 of them resulted in a live birth (LB), and 1,222 did not (NLB). Early morphokinetic parameters were compared between LB and NLB embryos from patients stratified into two age groups (<37 and ≥37 years), and between embryos at the same competence group from patients aged <37 and ≥37 years. The association of morphokinetic parameters with live birth was tested by univariate and multivariate analyses.

SETTING

Fertility clinic.

PATIENT(S)

The study population included 1,066 patients undergoing autologous intracytoplasmic sperm injection cycles with fresh single (SET), double (DET) or triple (TET) embryo transfers on day 2 or 3. Of them, 669 patients produced NLB embryos and 134 produced LB embryos.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Fertilization and cleavage morphokinetic parameters and live birth.

RESULT(S)

In the total patient population, all morphokinetic parameters were achieved earlier in LB compared with NLB embryos. The same was observed in patients aged <37 years (P<.015), but not ≥37 years. Except for the t8 (time at which an 8-blastomere embryo was identified), all morphokinetic parameters were reached earlier in LB embryos from patients aged <37 years compared with LB embryos from patients aged ≥37 years. Univariate analysis revealed that earlier occurrence of all morphokinetic parameters was associated with live birth, although only earlier t2 (time at which two separate and distinct cells were identified) was associated with live birth independently from maternal age in the multivariate analysis.

CONCLUSION(S)

Despite its retrospective nature and performance in a single IVF center, this study presents novel data indicating that embryos competent to provide a live birth display overall faster early developmental kinetics compared with embryos that do not achieve a live birth after transfer, a difference that, however, narrows as maternal age advances. The findings suggest that fertilization and cleavage morphokinetic parameters may constitute valuable references for embryo selection strategies aiming to improve live birth rates, specifically before advanced maternal age while holding limited usefulness in advanced maternal age.

Evaluation of fertilization, usable blastocyst development and sustained implantation rates according to intracytoplasmic sperm injection operator experience

RESEARCH QUESTION

Is intracytoplasmic sperm injection (ICSI) operator experience associated with fertilization, usable blastocyst development and sustained implantation rates (SIR) when at least two embryologists carry out ICSI for a single cohort of oocytes?

DESIGN

A retrospective cohort study of all IVF/ICSI cycles at a single large infertility centre between 2008 and 2018. Cycles were included if a cohort of oocytes was split between two embryologists for ICSI. The embryologist's experience of ICSI was used to evaluate laboratory and clinical outcomes overall and by pairs of inseminating embryologists. Logistic regression, analysis of variance and Kruskal-Wallis testing were used where appropriate.

RESULTS

Analysis of 14,362 ICSI procedures showed an association between least ICSI experience and lower mean fertilization rates (P < 0.0001), higher odds of failed fertilization (adjusted OR 4.3; P < 0.0001) and lower number of fertilization 'wins' per cohort (P < 0.0001). Usable blastocyst development rates (number of usable blastocysts/number of two pronuclear zygotes) were not associated with ICSI embryologist experience (P = 0.44), but the odds of obtaining no usable blastocysts were higher (adjusted OR 1.4; P < 0.0001) and the proportion of usable blastocyst 'wins' was lower (P = 0.0001) when embryologists with the least experience carried out ICSI. Increased ICSI experience was associated with higher mean SIR (P < 0.0001). Laboratory and clinical outcomes were similar among embryologists once 1000 ICSI cycles and above were carried out.

CONCLUSIONS

Increased ICSI operator experience is associated with higher fertilization rates, SIR and a lower likelihood of failed fertilization and usable blastocyst development. Splitting a single oocyte cohort between more than one embryologist for ICSI is a quality-control measure that can be implemented.