Decreased Endometrial Thickness Is Associated With Higher Risk of Neonatal Complications in Women With Polycystic Ovary Syndrome

PCOS phenotype focus: phenotype D under the magnifying glass

Polycystic ovary syndrome (PCOS) is defined as the combination of polycystic morphology, hyperandrogenism, and ovulatory disruption; this heterogeneity presents a conundrum for the medical community. The Rotterdam criteria have governed the diagnosis of PCOS, separating the patient cohort into four distinct phenotypes. It has been suggested that the lone normoandrogenic phenotype, so-called phenotype D, should not be classified as a PCOS subtype, with phenotypes A, B, and C displaying a hyperandrogenic biochemical and clinical profile thought to be characteristic of PCOS. To understand how to treat phenotype D patients, this review shines a spotlight on the phenotype, gathering various reports of how phenotype D is differentiated from the other PCOS phenotypes.

A sonographic endometrial thickness <7 mm in women undergoing in vitro fertilization increases the risk of placenta accreta spectrum

BACKGROUND

The prevalence of placenta accreta spectrum, a potentially life-threatening condition, has exhibited a significant global rise in recent decades. Effective screening methods and early identification strategies for placenta accreta spectrum could enable early treatment and improved outcomes. Endometrial thickness plays a crucial role in successful embryo implantation and favorable pregnancy outcomes. Extensive research has been conducted on the impact of endometrial thickness on assisted reproductive technology cycles, specifically in terms of pregnancy rates, live birth rates, and pregnancy loss rates. However, limited knowledge exists regarding the influence of endometrial thickness on placenta accreta spectrum.

OBJECTIVE

This study aimed to evaluate the association between preimplantation endometrial thickness and the occurrence of placenta accreta spectrum in women undergoing assisted reproductive technology cycles.

STUDY DESIGN

A total of 4637 women who had not undergone previous cesarean delivery and who conceived by in vitro fertilization or intracytoplasmic sperm injection-embryo transfer treatment and subsequently delivered at the Third Affiliated Hospital of Guangzhou Medical University between January 2008 and December 2020 were included in this study. To explore the relationship between endometrial thickness and placenta accreta spectrum, we used smooth curve fitting, threshold effect, and saturation effect analysis. Multivariate logistic regression analysis was performed to evaluate the independent association between endometrial thickness and placenta accreta spectrum while adjusting for potential confounding factors. Propensity score matching was performed to reduce the influence of bias and unmeasured confounders. Furthermore, we used causal mediation effect analysis to investigate the mediating role of endometrial thickness in the relationship between gravidity and ovarian stimulation protocol and the occurrence of placenta accreta spectrum.

RESULTS

Among the 4637 women included in this study, pregnancies with placenta accreta spectrum (159; 3.4%) had significantly thinner endometrial thickness (non-placenta accreta spectrum, 10.08±2.04 mm vs placenta accreta spectrum, 8.88±2.21 mm; P<.001) during the last ultrasound before embryo transfer. By using smooth curve fitting, it was found that changes in endometrial thickness had a significant effect on the incidence of placenta accreta spectrum up to a thickness of 10.9 mm, beyond which the effect plateaued. Then, the endometrial thickness was divided into the following 4 groups: ≤7, >7 to ≤10.9, >10.9 to ≤13, and >13 mm. The absolute rates of placenta accreta spectrum in each group were 11.91%, 3.73%, 1.35%, and 2.54%, respectively. Compared with women with an endometrial thickness from 10.9 to 13 mm, the odds of placenta accreta spectrum increased from an adjusted odds ratio of 2.27 (95% confidence interval, 1.33-3.86) for endometrial thickness from 7 to 10.9 mm to an adjusted odds ratio of 7.15 (95% confidence interval, 3.73-13.71) for endometrial thickness <7 mm after adjusting for potential confounding factors. Placenta previa remained as an independent risk factor for placenta accreta spectrum (adjusted odds ratio, 11.80; 95% confidence interval, 7.65-18.19). Moreover, endometrial thickness <7 mm was still an independent risk factor for placenta accreta spectrum (adjusted odds ratio, 3.91; 95% confidence interval, 1.57-9.73) in the matched cohort after PSM. Causal mediation analysis revealed that approximately 63.9% of the total effect of gravidity and 18.6% of the total effect of ovarian stimulation protocol on placenta accreta spectrum were mediated by endometrial thickness.

CONCLUSION

The findings of our study indicate that thin endometrial thickness is an independent risk factor for placenta accreta spectrum in women without previous cesarean delivery undergoing assisted reproductive technology treatment. The clinical significance of this risk factor is slightly lower than that of placenta previa. Furthermore, our results demonstrate that endometrial thickness plays a significant mediating role in the relationship between gravidity or ovarian stimulation protocol and placenta accreta spectrum.

Endometrial thickness and early pregnancy complications after frozen-thawed embryo transfers

Background

The relationship between endometrial thickness and pregnancy safety after in vitro fertilization treatment is an important topic that should provoke attention. The aim of this study was to demonstrate the relationship between endometrial thickness on day of embryo transfer and early pregnancy complications, including ectopic pregnancy and early miscarriage, in frozen thawed embryo transfer (FET) cycles.

Methods

Patients undergoing their first FET cycles were included into this study from January 2010 to December 2021. Patients were divided into three groups according to endometrial thickness on day of embryo transfer: Thin, ≤ 7 mm; Medium, 7-14 mm; Thick, ≥ 14 mm. Ectopic pregnancy and early miscarriage were the two primary outcomes. Endometrial thickness was the main measured variable. The risk factors of these two compilations were determined based on univariate analysis and multivariate logistic regression analysis.

Results

A total of 11138 clinical pregnancies were included. The overall ectopic pregnancy and early spontaneous miscarriage rates were 2.62% and 13.40%. The ectopic pregnancy and early spontaneous miscarriage rates were significantly higher in patients with thin endometrium as compared with those in the other two groups (ectopic pregnancy rate: 5.06% vs. 2.62% vs. 1.05%; P < 0.001; early spontaneous miscarriage rate: 15.18% vs. 13.45% vs. 11.53%; P < 0.001). In multivariate logistic regression analysis, thin endometrium was an independent factor to predict ectopic pregnancy [adjusted odds ratio (aOR): 5.62; 95% confidence interval (CI): 2.51-12.58, P < 0.001], and to predict early spontaneous miscarriage rate (aOR: 1.57; 95% CI: 1.21-1.74, P < 0.001).

Conclusion

Thin endometrium on day of embryo transfer in FET cycles is an independent predictor for early pregnancy compilations, including ectopic pregnancy and early spontaneous miscarriage.

The thicker the endometrium, the better the neonatal outcomes?

STUDY QUESTION

Is endometrial thickness (EMT) on the hCG trigger day related to the neonatal outcome of a single birth after fresh embryo transfer (ET)?

SUMMARY ANSWER

An EMT ≤7.8 mm was an independent predictor for greater odds of preterm delivery (PTD) of singletons born after fresh ET.

WHAT IS KNOWN ALREADY

There may be a positive association between live birth rates and EMT after fresh ET. It is still unknown whether a similar association is seen for the neonatal outcomes of singletons in fresh cycles.

STUDY DESIGN SIZE DURATION

This retrospective study involved singleton live births in women undergoing autologous IVF cycles during the period from 1 October 2016 to 31 July 2021.

PARTICIPANTS/MATERIALS SETTING METHODS

A total of 2010 women who fulfilled the inclusion criteria were included. A multivariable regression analysis was performed to detect the relationship between EMT and neonatal outcomes after controlling for potential confounders. Smooth curve fitting and threshold effect analysis were used to evaluate the accurate cutoff value of EMT.

MAIN RESULTS AND THE ROLE OF CHANCE

The results of the multivariate regression analyses showed that the odds of PTD were reduced by 45% with an EMT of 9.00-9.90 mm (adjusted odds ratio (OR): 0.55, 95% CI: 0.13 to 0.98; P = 0.0451), reduced by 58% with an EMT of 10.00-10.90 mm (adjusted OR: 0.42, 95% CI: 0.06 to 0.87; P = 0.0211) and reduced by 75% with an EMT >11 mm (adjusted OR: 0.25, 95% CI: 0.04 to 0.66; P = 0.0034), compared to the group with an EMT of 6.00-8.90 mm. It could also be seen from the adjusted smooth curves that the odds of PTD decreased and gestational age (GA) increased with increasing EMT. Combined with the analysis of threshold effects, the results indicated that when the EMT was ≤7.6 mm, the incidence of PTD decreased as the EMT gradually increased (adjusted OR: 0.47, 95% CI: 0.03 to 0.99; P = 0.0107), and when the EMT was ≤7.8 mm, the GA increased (adjusted β: 1.94, 95% CI: 1.26 to 2.63; P < 0.0001) as the EMT gradually increased.

LIMITATIONS REASONS FOR CAUTION

The main limitation of our study is its retrospective design. Although we found a significant decrease in PTD as the EMT increased, in terms of GA, the magnitude of the differences was modest, which may limit the clinical relevance of the findings.

WIDER IMPLICATIONS OF THE FINDINGS

Our data provide new insight into the relationship between EMT and neonatal outcomes by indicating that a thin endometrium of ≤7.8 mm is associated with an increased odds of PTD of singletons after fresh ET.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the National Natural Science Foundation of China (grant no. 82071717). There are no conflicts of interest.

Effect of endometrial thickness on obstetric and neonatal outcomes in assisted reproduction: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to explore the relationship of endometrial thickness (EMT) with obstetric and neonatal outcomes in assisted reproductive cycles.

METHODS

PubMed, EMBASE, Cochrane Library and Web of Science were searched for eligible studies through April 2023. Obstetric outcomes include placenta previa, placental abruption, hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM) and cesarean section (CS). Neonatal outcomes include birthweight, low birth weight (LBW), gestational age (GA), preterm birth (PTB), small for gestational age (SGA) and large for gestational age (LGA). The effect size was estimated as odds ratio (OR) or mean difference (MD) with 95% confidence interval (CI) using a random-effects model. Inter-study heterogeneity was assessed by the chi-square homogeneity test. One-study removal method was used to determine the sensitivity of the meta-analysis.

RESULTS

Nineteen studies involving 76,404 cycles were included. The pooled results revealed significant differences between the thin endometrium group and the normal group in placental abruption (OR = 2.45, 95% CI: 1.11-5.38, P = 0.03; I² = 0%), HDP (OR = 1.72, 95% CI: 1.44-2.05, P < 0.0001; I² = 0%), CS (OR = 1.33, 95% CI: 1.06-1.67, P = 0.01; I² = 77%), GA (MD = -1.27 day, 95% CI: -2.41- -1.02, P = 0.03; I² = 73%), PTB (OR = 1.56, 95% CI: 1.34-1.81, P < 0.0001; I² = 33%), birthweight (MD = -78.88 g, 95% CI: -115.79- -41.98, P < 0.0001; I² = 48%), LBW (OR = 1.84, 95% CI: 1.52-2.22, P < 0.00001; I² = 3%) and SGA (OR = 1.41, 95% CI: 1.17-1.70, P = 0.0003; I² = 15%). No statistical differences were found in placenta previa, GDM, and LGA.

CONCLUSION

Thin endometrium was associated with lower birthweight or GA and higher risks of placental abruption, HDP, CS, PTB, LBW and SGA. Therefore, these pregnancies need special attention and close follow-up by obstetricians. Due to the limited number of included studies, further studies are needed to confirm the results.

Thin endometrial lining: is it more prevalent in patients utilizing preimplantation genetic testing for monogenic disease (PGT-M) and related to prior hormonal contraceptive use?

STUDY QUESTION

Is a thin endometrial lining before ovulation triggering more prevalent in patients utilizing preimplantation genetic testing for monogenic disease (PGT-M) compared to the regular IVF/ICSI population and is this associated with prior hormonal contraceptive use?

SUMMARY ANSWER

Thin (<8 mm) endometrial lining is more prevalent in PGT-M patients compared to the regular IVF/ICSI population and is associated with both longer prior hormonal contraceptive use and a shorter cessation interval of hormonal contraceptives before IVF/ICSI treatment.

WHAT IS KNOWN ALREADY

Thin endometrial lining has been associated with lower pregnancy rates in IVF/ICSI cycles and increased chances of miscarriage and low birth weight. Endometrial thinning and atrophy occur during hormonal contraceptive use. Patients utilizing PGT-M typically use hormonal contraceptives up until treatment to avoid the risk of conception of a genetically affected child. Whether this could negatively affect endometrial thickness achieved during subsequent IVF/ICSI cycles is not known.

STUDY DESIGN, SIZE, DURATION

A retrospective case control study was performed, including all PGT-M patients attending the University Medical Centre Groningen (cases), between 2009 and 2018. The control group consisted of two non-PGT IVF/ICSI patients for each PGT-M patient, matched for age and treatment period.

PARTICIPANTS/MATERIALS, SETTING, METHODS

First cycles of 122 PGT-M patients and 240 controls were included. Cessation interval of hormonal contraceptives was categorized as late cessation (cessation <1 year prior to treatment) or early cessation (>1 year prior to treatment). Endometrial thickness was routinely measured on the day of hCG triggering or 1 day prior. The prevalence of an endometrial lining <8 mm was compared between PGT-M patients and controls. Hormonal contraceptive use (both duration and cessation interval) was compared between both groups. Univariable and multivariable regression analyses were performed to identify risk factors for thin endometrial lining. In addition, cycle and pregnancy outcomes were compared within control/PGT-M groups between patients with endometrial lining > or <8 mm.

MAIN RESULTS AND THE ROLE OF CHANCE

Thin endometrial lining on the day of hCG triggering was found significantly more often in the PGT-M group, compared to controls: 32% vs 11% (mean difference 21.0%, 95% CI: 11.7, 30.3%). As expected, more patients in the PGT-M group ceased their hormonal contraception late (<1 year): 64% vs 2% in the control group (mean difference 61.9%, 95% CI: 53.0, 70.8%). Average duration of hormonal contraceptive use was 10.6 years in the PGT-M group vs 9.3 years in controls (mean difference 1.3 years, 95% CI: 0.2, 2.3 years). Multivariable logistic regression analysis identified late cessation (OR: 6.0, 95% CI: 1.9-19.2) and duration of prior hormonal contraceptive use (OR per year increase 1.1, 95% CI: 1.0-1.2) as significant independent risk factors for a thin endometrial lining. In relation to outcome, we found a statistically significant increase in miscarriage rate in PGT-M patients with an endometrial lining <8 mm compared to those with an endometrial lining >8 mm (20.0% vs 1.7%, mean difference 18.3%, 95% CI: 2.3, 34.3%). A trend towards lower birth weight and gestation- and gender-adjusted birth weight (z-score) was also found in this group. No statistically significant differences were detected in pregnancy rate, live birth rate, or incidence of preterm delivery or SGA. Within the control group, no statistically significant differences were found in outcomes between patients with an endometrial lining <8 compared to an endometrial lining >8 mm.

LIMITATIONS, REASONS FOR CAUTION

The study is retrospective. Various types of hormonal contraceptives were reported which possibly exert different effects on the endometrial lining. In relation to pregnancy outcome measures, numbers were very limited; therefore, no firm conclusions should be drawn.

WIDER IMPLICATIONS OF THE FINDINGS

This study provides further insight into the role of prior hormonal contraceptive use as a possible contributor to the occurrence of thin endometrial lining during ART treatment. Future studies should provide more information on its clinical relevance, to determine whether PGT-M patients can be reassured, or should be counselled to stop hormonal contraceptive use and change to an alternative contraceptive method prior to PGT treatment.

STUDY FUNDING/COMPETING INTERESTS

No specific funding was used and no conflicts of interests are declared.

TRIAL REGISTRATION NUMBER

N/A.

The role of timing in frozen embryo transfer

The process of implantation is characterized by a complex cross-talk between the endometrium and the blastocyst, with the endometrium only being receptive to implantation during a transient window of implantation of approximately 2-3 days during the midsecretory phase. The timing of embryo transfer, including frozen embryo transfer, is therefore critical to the success of implantation. In this article, we discuss various elements that may guide the timing of frozen embryo transfer, including the role of endometrial characteristics such as thickness, days postovulation or length of progesterone administration, stage of the embryo, and the application of endometrial receptivity tests to guide personalized embryo transfer.