Associations between dyslipidaemia and pregnancy outcomes in the first complete cycle of IVF/ICSI: a real-world analysis

Peripheral fatty acids and outcome of assisted reproduction

OBJECTIVES

The present study investigated the relationship between fatty acid levels in whole blood in women undergoing in vitro fertilization and four successive assisted reproductive technology (ART) outcomes.

METHODS

A cross-sectional study was performed on data from a prospective cohort study conducted between 2014 and 2016.

RESULTS

Participants were 238 women undergoing in vitro fertilization and participating in a study on the role of lifestyle habits and diet in ART outcomes. Blood polyunsaturated fatty acids were measured by gas chromatography. Overall, higher blood levels of monounsaturated fatty acids and oleic acid and higher ω-6/ω-3 ratio and arachidonic/docosahexaenoic acid ratio were associated with more favorable ART outcomes. By contrast, higher concentrations of long chain polyunsaturated fatty acids tended to be negatively associated with the considered outcomes.

CONCLUSIONS

Further prospective studies are needed to determine the ranges of fatty acid concentrations that are optimal for women with subfertility.

Correlation of dyslipidemia characterized by abnormal cholesterol in first trimester with early pregnancy loss: a retrospective study

PURPOSE

Dyslipidemia has been linked to adverse pregnancy outcomes in observational studies. This study aimed to explore how variations in lipid levels during the first trimester might influence early pregnancy loss (EPL).

METHODS

Blood samples from pregnant women were analyzed to examine the relationship between EPL and lipid metabolism using logistic regression and restricted cubic splines (RCS). Sensitivity analysis was conducted to verify the robustness of the results.

RESULTS

Elevated low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) levels at most times of 4-9 weeks of gestation were associated with a higher risk of EPL, regardless of whether the control group was successful pregnancy or live birth. Specifically, taking the successful pregnancy group as a control example, increased EPL risks were observed in the highest quartile of plasma TC at 4 weeks (OR = 2.18, 95%: 1.14-4.21) and 7 weeks (OR = 4.30, 95%: 1.87-9.93) of pregnancy. Significant EPL risks were also noted in the third (Q3) and fourth (Q4) quartiles of LDL-C at 4 weeks (Q3, OR = 2.98, 95%: 1.47-6.08; Q4, OR = 2.66, 95%: 1.27-5.55) and 7 weeks (Q3, OR = 3.12, 95%: 1.44-6.73; Q4, OR = 5.17, 95%: 2.14-12.49). High TC levels (> 3.25-3.78 mmol/L) and high LDL-C levels (> 1.92-2.04 mmol/L) were linked to an increased risk of EPL compared to lower levels of TC (≤ 2.91-3.05 mmol/L) and LDL-C (≤ 1.64-1.75 mmol/L).RCS analysis further confirmed this finding that plasma TC and LDL-C levels at 4 and 7 weeks of gestation may have a linear relationship with the risk of EPL. By the way, triglyceride levels at 6 and 8 weeks of gestation were associated with a higher risk of EPL, whereas high-density lipoprotein cholesterol (HDL-C) levels at 5 and 9 weeks of gestation have a completely opposite relationship with EPL risk.

CONCLUSIONS

Elevated cholesterol levels during the first trimester are associated with an increased risk of early pregnancy loss, emphasizing the need for lipid monitoring during pregnancy and even before pregnancy.

Hyperlipidemia negatively impacts implantation by dysregulating tight junction and Claudin-3 and Claudin-4 expression in the endometrium

Clinical observational studies have suggested hyperlipidemia may disturb embryo implantation through endometrium; however, the mechanism has been unclear. With its profound implications for reproductive health, the present study aims to investigate whether hyperlipidemia affects endometrial epithelial cell tight junctions for implantation failures. By constructing hyperlipidemia mice model, the number and distribution of embryo implantation status were investigated after both natural mating and in vitro fertilization and embryo transfer (IVF-ET). Transmission electron microscopy (TEM) was used to compare the ultrastructure of tight junctions in endometrial endothelial cells. Western blot and immunofluorescence were used to explore the expression and localization of tight junction proteins, such as Claudin (CDLN)3, CLDN4, occludin (OCLN), and zonula occludens-1 (ZO1). For women with reproductive failure, mid-luteal phase endometrial tissues were collected, and gene expression of tight junction proteins was investigated using RNA sequencing and qRT-PCR. In hyperlipidemic mice, the number of embryo implantation sites significantly decreased with uneven distribution after natural mating and IVF-ET. Disrupted tight junctions were found, characterized by a decreased number of tight junctions by TEM, downregulated expressions of CDLN4, OCLN, and ZO1, and an increased expression of CLDN3 by western blot. In hyperlipidemic women with reproductive failure, the dysregulated expression of CLDN3 and CLDN4 was also present in the luteal phase endometrium. In this study, evaluation of both animal models and infertile women in vivo demonstrated that hyperlipidemia reduced female fertility, accompanied by disruption of tight junction structures and dysregulation of CLDN3 and CLDN4 expression in the endothelial cells of luteal phase endometrium.

Effects of high-normal fasting blood glucose on ART outcomes of frozen-thawed single blastocyst transfer in women with normal BMI

PURPOSE

This retrospective cohort study aims to investigate whether high-normal fasting blood glucose (FBG) affects assisted reproductive technology (ART) outcomes undergoing single blastocyst frozen-thawed embryo transfer (FET) cycles in women with normal body mass index (BMI).

METHODS

944 women with normal BMI and FBG levels undergoing single blastocyst FET cycles were enrolled. Based on the median of FBG (4.97 mmol/L, 1 mmol/L = 18 mg/dL), the subjects were categorized into the low-normal group (3.90 ≤ FBG ≤ 4.97 mmol/L, n = 472) and the high-normal group (4.97 < FBG < 6.10 mmol/L, n = 472). Multivariable logistic regression and receiver operating characteristic (ROC) were used to analyze the relationship between high-normal FBG and ART outcomes.

PRIMARY OUTCOME

live birth rate (LBR).

RESULTS

LBR was significantly lower in the high-normal group than in the low-normal group (36.8% vs. 45.1%, p = 0.010), and the miscarriage rate was considerably higher than that in the low-normal group (23.9% vs. 16.5%, p = 0.041). High-normal FBG of female was an independent predictor of live birth (adjusted OR:0.747, 95% CI: 0.541-0.963, p = 0.027) and miscarriage (adjusted OR:1.610, 95% CI: 1.018-2.547, p = 0.042). ROC analyses showed that the cut-off values of FBG (endpoints: live birth and miscarriage) were 5.07 mmol/L, and 5.01 mmol/L, respectively.

CONCLUSIONS

In women with normal BMI, high-normal FBG is an independent risk factor for lower LBR and higher miscarriage rate in single blastocyst FET cycles. Attention to preconception FBG monitoring in this particular population may allow early intervention to improve ART outcomes.

Effects of Metabolic Syndrome on Pregnancy Outcomes in Women Without Polycystic Ovary Syndrome

Context

Metabolic syndrome (MetS) is a cluster of metabolic risk factors that predict cardiovascular disease. Previous studies suggested that MetS impaired clinical outcomes in women with polycystic ovary syndrome (PCOS) undergoing in vitro fertilization (IVF).

Objective

To evaluate the effects of MetS on IVF/intracytoplasmic sperm injection (ICSI) outcomes in women without PCOS.

Methods

This retrospective study collected 8539 eligible women without PCOS who came for their first cycle of IVF/ICSI to the Institute of Women, Children and Reproductive Health, Shandong University, from 2017 to 2020, including 1147 subjects in the MetS group and 7392 in the control group. The primary outcome was live birth. Secondary outcomes included other pregnancy outcomes and the risk of maternal and neonatal complications.

Results

Women in the MetS group had a lower live birth rate (50.6% vs 54.9%, adjusted odds ratio [aOR] 0.87, 95% CI 0.75-1.00, P = .045) and higher risks of late miscarriage (5.8% vs 3.3%, aOR 1.52, 95% CI 1.02-2.27, P = .041), gestational diabetes mellitus (13.7% vs 7.0%, aOR 1.84, 95% CI 1.30-2.60, P = .001), hypertensive disorder of pregnancy (7.8% vs 3.5%, aOR 1.79, 95% CI 1.14-2.83, P = .012), and preterm birth (9.0% vs 4.4%, aOR 2.03, 95% CI 1.33-3.08, P = .001). Singleton newborns in the MetS group were at higher risk of large for gestational age (33.3% vs 20.5%, aOR 1.66, 95% CI (1.31-2.13), P < .001) but at lower risk of small for gestational age (2.7% vs 6.2%, aOR 0.48, 95% CI 0.25-0.90, P = .023).

Conclusion

MetS was associated with adverse IVF/ICSI outcomes in women without PCOS.

Hyperlipidemia is negatively associated with pregnancy outcomes in patients following frozen-thawed embryo transfer: A retrospective study

Background and Aims

It is demonstrated that lipid metabolism disorders are associated with the reproductive performances of assisted reproductive technology. However, it is little known whether hyperlipidemia is associated with the endometrial receptivity and pregnancy outcomes of patients undergoing frozen-thawed embryo transfer (FET).

Methods

This was a retrospective analysis involving 554 infertile women undergoing FET. The patients were divided into the hyperlipidemia group (n = 224) and control group (n = 320) based on the levels of serum lipids. The clinical and laboratory indexes between the two groups were compared. Meanwhile, the stratified analysis based on body mass index (BMI) and endometrial preparation protocols was performed. The independent samples t-test, Mann-Whitney U test, χ2 test and multiple logistic regression analysis were used to compare and analyze the data.

Results

The patients with hyperlipidemia had significantly higher serum lipids levels and BMI and lower clinical pregnancy and implantation rates than those with normal blood lipids (p < 0.05). The impact of hyperlipidemia on pregnancy outcomes was independent of BMI. The multiple logistic regression analysis showed that higher cholesterol was associated with lower pregnancy rate and implantation rate (p < 0.05). Regardless of blood lipid levels, the patients undergoing the hormone replacement therapy (HRT) protocol had higher estradiol levels and lower progesterone levels compared with the stimulated cycles (STC) (p < 0.05). Moreover, the clinical pregnancy rate and implantation rate of the HRT protocol were higher than those of the STC, although there was no significant difference between the two.

Conclusion

Hyperlipidemia especially higher cholesterol has a negative effect on the pregnancy outcomes of the patients undergoing FET. Actively implementing lipid-lowering treatment and the HRT protocol seem more friendly for these patients.

Chromosomal polymorphisms have no negative effect on reproductive outcomes after IVF/ICSI-ET/FET

The present study aimed to explore whether chromosomal polymorphisms (CPs) have negative effects on reproductive outcomes of in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET)/frozen-thawing embryo transfer (FET)? We conducted a retrospective study consisting of 21,867 assisted reproductive technology treatment cycles, among which, fresh embryo transfer cycles accounted for 10,400, and the rest were FET cycles. According to karyotype of CPs, the former was grouped as: group 1 (male carrier, n = 425), group 2 (female carrier, n = 262), and group 3 (couple without CPs, n = 9713). Accordingly, FET cycles were divided into 3 groups: group 4 (male carrier, n = 298), group 5 (female carrier, n = 311), and group 6 (couple without CPs, n = 10,858). The embryo implantation rate (IR), clinical pregnancy rate (CPR), live birth rate (LBR), and early miscarriage rate (EMR) were compared among the groups. In fresh embryo transfer cycles after IVF/ICSI, there were no significant differences in the infertility duration, BMI, basal FSH, no. of oocyte, no. of 2PN, endometrial thickness on trigger day, serum E2, P, and LH level on trigger day (P > 0.05). The female age, no. of 2PN embryo cleavage, top-quality embryo, and no. of embryo transferred were significantly different among groups (P < 0.05). The IR was 38.8%, 36.2%, and 34.0% in groups 1, 2, and 3, respectively. The CPR was 55.1%, 52.3%, and 49.7%, respectively. The LBR was 36.9%, 37.4%, and 36.4%, respectively. The CPR and LBR showed no significant differences among groups. The IR was lower and the EMR was higher in group 3 than those of groups 1 and 2. Binary logistic regression analysis indicated that female age, no. of embryo transferred, EMT, LH, and P on the trigger day were independently factors associated with CPR. Besides, no. of embryo transferred, and EMT on trigger day were associated with LBR, while the CPs was not related with CPR and LBR after IVF/ICSI-ET. In FET cycles, the infertility duration was similar (P > 0.05), but the female age, BMI, no. of embryo transferred were significantly different among groups (P > 0.05). The IR was 24.3%, 23.6% and 22.3% in group 4, 5, and 6, receptivity. The CPR was 31.8%, 30.9%, and 30.0%, the LBR was 23.8%,26.3%, and 23.8%, while the EMR was 12.6%, 13.1%, 14.4%, respectively. The IR, CPR, EMR, and LBR showed no significant differences among groups (P > 0.05). Binary logistic regression analysis indicated that female age, infertility duration, and no. of embryo transferred were independently factors affecting CPR and LBR after FET. The CPs were not associated with CPR and LBR after FET. The results suggested that uniparental carrying of CPs have no effects on the reproductive outcomes after IVF/ICSI-ET/FET. However, it is not clear whether both parents carrying CPs would affect pregnancy outcome.

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.

Homeostatic Model Assessment for Insulin Resistance Is Associated With Late Miscarriage in Non-Dyslipidemic Women Undergoing Fresh IVF/ICSI Embryo Transfer

OBJECTIVE

To evaluate the associations between homeostatic model assessment for insulin resistance (HOMA-IR) and pregnancy outcomes in non-dyslipidemic infertile women undergoing in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET).

MATERIALS AND METHODS

This is a retrospective study involving 3,615 non-dyslipidemic infertile women who attend to the Reproductive Medicine Center of Xiangya Hospital, Central South University (CSU) between January 2014 and October 2021. Eligible participants were divided into three groups according to the quartiles of HOMA-IR: Group 1 (HOMA-IR <1.46), Group 2 (1.46 to <2.71) and Group 3 (HOMA-IR ≥2.71). Baseline data, clinical characteristics during the assisted reproductive technology (ART) procedure, pregnancy, and neonatal outcomes were compared among the three groups. Subgroup analysis based on presence or absence of the polycystic ovary syndrome (PCOS) status was also performed to analyze the effects of HOMA-IR among non-PCOS populations.

RESULTS

The late miscarriage rate and percentage of macrosomia increased with the HOMA-IR group (for late miscarriage rate: 2.23% vs. 3.04% vs. 7.35%, P<0.001; for macrosomia: 0.21% vs. 1.70% vs. 3.23%, P=0.002). Increased HOMA-IR (HOMA-IR≥2.71) was positively associated with late miscarriage (crude OR 3.50, 95% CI 1.64-7.47, P=0.001; adjusted OR 3.56, 95% CI 1.56-8.15, P=0.003). In the subgroup analysis, there were 3,165 participants in the non-PCOS group and 450 were assigned to the PCOS group. Late miscarriage rate increased with the HOMA-IR group among non-PCOS populations (2.20% vs. 3.03% vs. 7.67%, P<0.001). Late miscarriage rate of PCOS women were comparable among the three HOMA-IR groups (2.50% vs. 3.06% vs. 5.71%, P=0.634). Among non-PCOS women, increased HOMA-IR (HOMA-IR≥2.71) was positively associated with late miscarriage (crude OR 3.71, 95% CI 1.66-8.30, P=0.001; adjusted OR 3.82, 95% CI 1.59-9.17, P=0.003).

CONCLUSIONS

Late miscarriage rate and prevalence of macrosomia increased with the HOMA-IR index. Preconception HOMA-IR is an independent risk factor for late miscarriage in normolipidemic women undergoing IVF/ICSI-ET. Controlling insulin resistance before ART might prevent the occurrence of late miscarriage and macrosomia.

Impact of dyslipidemia on the cumulative pregnancy outcomes after first ovarian stimulation

OBJECTIVES

To investigate the cumulative live birth rate (CLBR) according to lipid metabolism in patients with or without polycystic ovarian syndrome (PCOS) undergoing their first complete in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles.

PATIENTS

A total of 1,470 patients with PCOS and 3,232 patients without PCOS who underwent their first complete IVF/ICSI cycles from January 2016 to June 2018 were included. During a minimum of 2 years of follow-up, they had achieved at least one live birth or used all available embryos. The cumulative pregnancy outcomes were compared based on the patients' blood lipid parameters, including triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), in the two populations. Patients with an abnormal level of one or more of these four indicators were considered the dyslipidemia group. Patients whose four indicators were normal were considered the control group.

RESULTS

Among 1,470 patients with PCOS, the cumulative pregnancy outcomes were similar in the dyslipidemia group and control group. Logistic regression analysis showed that the TC levels were significantly negatively associated with the cumulative live birth rate (CLBR) after adjustment for confounding factors such as age and BMI (aOR 0.81, 95% CI 0.66-0.98, P<0.05). Among the 3,232 patients without PCOS, there was no significant difference in the cumulative pregnancy outcomes between the dyslipidemia group and the control group. No significant correlations were found in other logistic regression analyses.

CONCLUSIONS

TC negatively impacts the CLBR after first ovarian stimulation in PCOS patients. PCOS patients with dyslipidemia caused by elevated TC may have a poor CLBR.