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

Association between body mass index and in vitro fertilization/intra-cytoplasmic sperm injection outcomes: An analysis of 15,124 normal ovarian responders in China

BACKGROUND

High body mass index (BMI) results in decreased fecundity, and women with high BMI have reduced rates of clinical pregnancy and live birth in in vitro fertilization/intra-cytoplasmic sperm injection (IVF/ICSI). Meanwhile, ovarian responses show great heterogeneity in patients with a high BMI. This study aimed to analyze the effects of a high BMI on IVF/ICSI outcomes in the Chinese female with normal ovarian response.

METHODS

We performed a retrospective cohort study comprising 15,124 patients from the medical record system of the Reproductive Center of Peking University Third Hospital, with 3530 (23.3%) in the overweight group and 1380 (9.1%) in the obese group, who had a normal ovarian response (5-15 oocytes retrieved) and underwent fresh embryo transfer (ET) cycles from January 2017 to December 2018, followed by linked frozen-thawed embryo transfer (FET) cycles from January 2017 to December 2020. Cumulative live birth rate (CLBR) was used as the primary outcome. Furthermore, a generalized additive model was applied to visually illustrate the curvilinear relationship between BMI and the outcomes. We used a decision tree to identify the specific population where high BMI had the greatest effect on IVF/ICSI outcomes.

RESULTS

High BMI was associated with poor IVF/ICSI outcomes, both in cumulative cycles and in separate fresh ET or FET cycles. In cumulative cycles, compared with the normal weight group, obesity was correlated with a lower positive pregnancy test rate (adjusted odds ratio [aOR]: 0.809, 95% confidence interval [CI]: 0.682-0.960), lower clinical pregnancy rate (aOR: 0.766, 95% CI: 0.646-0.907), lower live birth rate (aOR: 0.706, 95% CI: 0.595-0.838), higher cesarean section rate (aOR: 2.066, 95% CI: 1.533-2.785), and higher rate of large for gestational age (aOR: 2.273, 95% CI: 1.547-3.341). In the generalized additive model, we found that CLBR declined with increasing BMI, with 24 kg/m 2 as an inflection point. In the decision tree, BMI only made a difference in the population aged ≤34.5 years, with anti-Mullerian hormone >1.395 ng/mL, and the first time for IVF.

CONCLUSIONS

High BMI was related to poor IVF/ICSI outcomes in women with a normal ovarian response, and CLBR declined with increasing BMI, partly due to suppressed endometrial receptivity. A high BMI had the most negative effect on young women with anticipated positive prognoses.

Higher live birth rates are associated with a normal body mass index in preimplantation genetic testing for aneuploidy frozen embryo transfer cycles: a Society for Assisted Reproductive Technology Clinic Outcome Reporting System study

OBJECTIVE

To determine whether body mass index (BMI) was associated with live birth in patients undergoing transfer of frozen-thawed preimplantation genetic testing for aneuploidy (PGT-A) embryos.

DESIGN

Retrospective cohort study of cycles reported to the Society for Assisted Reproductive Technology Clinic Outcome Reporting System.

SUBJECTS

All autologous and donor recipient PGT-A-tested cycles reported to the Society for Assisted Reproductive Technology Clinic Outcome Reporting System from 2014 to 2017.

INTERVENTION(S)

Body mass index.

MAIN OUTCOME MEASURE(S)

The primary outcome measure was the live birth rate, and the secondary outcome measures were the clinical pregnancy and biochemical pregnancy rates. Multivariable generalized additive mixed models and log-binomial models were used to model the relationship between BMI and outcome measures.

RESULT(S)

A total of 77,018 PGT-A cycles from 55,888 patients were analyzed. Of these cycles, 70,752 were autologous, and 6,266 were donor recipient. In autologous cycles, a statistically significant and clear nonlinear relationship was observed between the BMI and live birth rates, with the highest birth rates observed for the BMI range of 23-24.99 kg/m2. When using 23-24.99 kg/m2 as the referent, other BMI ranges demonstrated a lower probability of live birth and clinical pregnancy that continued to decrease as the BMI moved further from the reference value. Patients with a BMI of <18.5 kg/m2 had a 11% lower probability of live birth, whereas those with a BMI of ≥40 kg/m2 had a 27% lower probability than the referent.

CONCLUSION(S)

A normal-weight BMI range of 23-24.99 kg/m2 was associated with the highest probability of clinical pregnancy and live birth after a frozen-thawed PGT-A-tested blastocyst transfer in both autologous and donor recipient cycles. A BMI outside the range of 23-24.99 kg/m2 is likely associated with a malfunction in the implantation process, which is presumed to be related to a uterine factor and not an oocyte factor, as both autologous and donor recipient cycle outcomes were associated similarly with the BMI of the intended parent.

Does body mass index compromise assisted reproductive technique outcomes? A cross-sectional study

Background

Overweight and obese people face several health problems. Female obesity has been shown to reduce fertility in the general population. Assisted reproductive technology outcomes in obese cases are widely studied, but the results are inconclusive.

Objective

This study aimed to compare live birth rate (LBR) among women with 4 different types of body mass index (BMI).

Materials and Methods

In this cross-sectional study, data of 1611 women, who were candidates for fresh and frozen embryo transfer cycles, was extracted from 2051 medical files at the Reproductive Sciences Institute, Yazd, Iran from May 2019-May 2021. The participants were divided into 4 groups (underweight, normal, overweight, and obese) according to their BMI, and LBR was considered to be the main outcome.

Results

Of 1611 women, 39 were underweight, 585 were normal, 676 were overweight, and 311 were obese. Underweight women had the lowest LBR (12.8%), but there was no statistically significant difference (p = 0.55). In addition, LBR was compared in the 4 BMI groups according to age, type of transfer cycle (fresh or freeze), and cause of infertility, and there was comparable LBR in the 4 BMI groups. However, metaphase 2 oocyte rate, doses of gonadotropin usage in the cycles, and estradiol level had statistically significant differences (p < 0.001).

Conclusion

According to our study, obesity does not affect LBR in the IVF cycle, regardless of fresh or frozen embryo transfer cycles, different age groups, and causes of infertility.

Effect of body mass index on the cumulative live birth rate over multiple complete IVF cycles in women with polycystic ovary syndrome: A retrospective study

OBJECTIVE

The purpose of this study was to investigate the effect of body mass index (BMI) before treatment on the cumulative live birth rate (CLBR) over multiple complete in vitro fertilization (IVF) cycles in patients with polycystic ovary syndrome (PCOS).

MATERIALS AND METHODS

This study is a single-center retrospective cohort study. It included 5016 patients with PCOS who started their first IVF cycle in our hospital between 2009 and 2018. Kaplan-Meier and log-rank tests were used for the comparison of CLBR across BMI groups. Univariate, multivariate models and stratification analysis were used to evaluate possible influencing factors of CLBR. Smoothing curve fitting was applied to present the correlation between BMI and CLBR. A one-line linear regression model was compared with a two-piecewise linear model using a log-likelihood ratio test.

RESULTS

During the 8-year follow-up, 3604 women (71.85%) obtained at least one live birth. The study population was grouped according to BMI, with BMI ranging from [14.53-23.00) kg/m² in the normal weight group, [23.00-27.50) kg/m² in the overweight group, and [27.50-37.80] kg/m² in the obese group, respectively. The CLBR of the obese group and the overweight group were significantly lower than the normal weight group. In the multivariate regression model, HR for CLBR was 0.86 [95%CI: 0.78-0.95] for the obese group, and 0.93 [0.86-1.00] for the overweight group, compared with the normal weight group as control. The curve fitting after adjustment for confounding factors and log-likelihood ratio test showed a one-line linear negative correlation between BMI and CLBR.

CONCLUSION

We concluded that the BMI of PCOS patients had a negative one-line linear correlation with CLBR over multiple complete cycles.

Lipid metabolism and endometrial receptivity

BACKGROUND

Obesity has now been recognized as a high-risk factor for reproductive health. Although remarkable advancements have been made in ART, a considerable number of infertile obese women still suffer from serial implantation failure, despite the high quality of embryos transferred. Although obesity has long been known to exert various deleterious effects on female fertility, the underlying mechanisms, especially the roles of lipid metabolism in endometrial receptivity, remain largely elusive.

OBJECTIVE AND RATIONALE

This review summarizes current evidence on the impacts of several major lipids and lipid-derived mediators on the embryonic implantation process. Emerging methods for evaluating endometrial receptivity, for example transcriptomic and lipidomic analysis, are also discussed.

SEARCH METHODS

The PubMed and Embase databases were searched using the following keywords: (lipid or fatty acid or prostaglandin or phospholipid or sphingolipid or endocannabinoid or lysophosphatidic acid or cholesterol or progesterone or estrogen or transcriptomic or lipidomic or obesity or dyslipidemia or polycystic ovary syndrome) AND (endometrial receptivity or uterine receptivity or embryo implantation or assisted reproductive technology or in vitro fertilization or embryo transfer). A comprehensive literature search was performed on the roles of lipid-related metabolic pathways in embryo implantation published between January 1970 and March 2022. Only studies with original data and reviews published in English were included in this review. Additional information was obtained from references cited in the articles resulting from the literature search.

OUTCOMES

Recent studies have shown that a fatty acids-related pro-inflammatory response in the embryo-endometrium boundary facilitates pregnancy via mediation of prostaglandin signaling. Phospholipid-derived mediators, for example endocannabinoids, lysophosphatidic acid and sphingosine-1-phosphate, are associated with endometrial receptivity, embryo spacing and decidualization based on evidence from both animal and human studies. Progesterone and estrogen are two cholesterol-derived steroid hormones that synergistically mediate the structural and functional alterations in the uterus ready for blastocyst implantation. Variations in serum cholesterol profiles throughout the menstrual cycle imply a demand for steroidogenesis at the time of window of implantation (WOI). Since 2002, endometrial transcriptomic analysis has been serving as a diagnostic tool for WOI dating. Numerous genes that govern lipid homeostasis have been identified and, based on specific alterations of lipidomic signatures differentially expressed in WOI, lipidomic analysis of endometrial fluid provides a possibility for non-invasive diagnosis of lipids alterations during the WOI.

WIDER IMPLICATIONS

Given that lipid metabolic dysregulation potentially plays a role in infertility, a better understanding of lipid metabolism could have significant clinical implications for the diagnosis and treatment of female reproductive disorders.

The Impact of the Main Negative Socio-Economic Factors on Female Fertility

The negative relationship between fertility and income is well known to economists and demographers. Developed countries have experienced a remarkable decline in their fertility rate as they have become richer. Lifestyle choices can affect a woman’s ability to conceive. Tobacco use and heavy drinking is associated with an increased risk of ovulation disorders, and being overweight or significantly underweight can inhibit normal ovulation. Our research is focused on evaluating the main risk factors that influence female fertility. We assembled a country-specific dataset on birth rate and socio-economic factors for 171 countries, using data integrated from publicly available data sources. The regression model shows that the negative factor with the greatest impact on female fertility is represented by the level of income per capita. The negative effects of smoking, alcohol consumption, and body weight on female fertility are also demonstrated, but with a lower impact compared to the average income per capita.

[Obesity affects the chances of birth after frozen-thawed blastocyst transfer]

OBJECTIVES

Both the number of frozen-thawed embryo transfers and the incidence of obesity have increased sharply in recent years in Assisted Reproductive Technology (ART) centers. The objective of our study is therefore to evaluate the impact of female obesity on pregnancy outcomes for frozen-thawed embryo transfer at blastocyst stage.

METHODS

This is a single-center retrospective study conducted between January 1, 2016, and December 31, 2019, in our Assisted Reproduction Center in Calais. All consecutive cycles of frozen embryo transfers at blastocyst stage with artificial cycle were included. A total of 296 cycles could be included corresponding to 220 cycles realized in normal Body Mass Index (BMI) patients (18.5-24.9kg/m²) and 76 in obese patients (BMI≥30kg/m²).

RESULTS

Live birth rates and implantation rates were significantly lower in obese patients compared with patients with a normal BMI (respectively 9.2 % vs. 22.3 % and 10 % vs. 20.8 %, P=0.01 and P<0.01).

CONCLUSIONS

Therefore, our study showed that obesity is associated with a lower rate of live birth and implantation following frozen-thawed blastocyst transfers in artificial cycles. This could be explained by different factors that can be both embryonic and/or extra-embryonic.

Maternal body mass index associates with blastocyst euploidy and live birth rates: the tip of an iceberg?

RESEARCH QUESTION

Does maternal preconceptional body mass index (BMI) associate with mean blastocyst euploidy rate (m-ER) per patient and live birth rate (LBR) after vitrified-warmed euploid single embryo transfer (SET)?

DESIGN

Observational study conducted between April 2013 and March 2020 at a private IVF clinic, involving 1811 Caucasian women undergoing trophectoderm biopsy and comprehensive chromosome testing. The outcomes of 1125 first vitrified-warmed euploid SET were also analysed. Patients were clustered as normal weight (BMI 18.5-25; n = 1392 performing 859 SET), underweight (BMI <18.5; n = 160 performing 112 SET) and overweight (BMI >25; n = 259 performing 154 SET). m-ER per patient was the primary outcome. The secondary outcomes were all clinical outcomes per euploid SET. All data were adjusted for confounders through regression analyses.

RESULTS

The m-ER per patient decreases as maternal BMI increases from 17 up to 22-23 before reaching a plateau. A linear regression adjusted for maternal age confirmed this moderate association (unstandardized coefficient B: -0.6%, 95% confidence interval [CI]: -1.1 to -0.1%, P = 0.02). All clinical outcomes were similar between normal weight and underweight women. Overweight women, instead, showed higher miscarriage rate per clinical pregnancy (n = 20/75, 26.7% versus n = 67/461, 14.5%; odds ratio [OR] adjusted for blastocyst quality and day of full blastulation: 2.0, 95% CI: 1.1-3.6, P = 0.01) and lower LBR per SET (n = 55/154, 35.7% versus n = 388/859, 45.2%; OR adjusted for blastocyst quality and day of full blastulation: 0.67, 95% CI: 0.46-0.96, P = 0.03).

CONCLUSION

These data indicate a need for future research on more sensitive metrics to assess body fat mass and distribution, as well as on the mechanisms leading to lipotoxicity, thereby impairing embryo competence and/or endometrial receptivity. Overweight women should be informed of their higher risk for miscarriage and, whenever possible, encouraged to lose weight, especially before transfer.