Early and late pregnancy loss in women with polycystic ovary syndrome undergoing IVF/ICSI treatment: a retrospective cohort analysis of 21 820 pregnancies

Higher Cumulative Live Birth Rate but Also Higher Late Miscarriage Risk in Non-Obese Women with Polycystic Ovary Syndrome Undergoing the First IVF/ICSI Cycle

Purpose

To determine the impact of polycystic ovary syndrome on in vitro fertilization/intracytoplasmic sperm injection and embryo transfer outcomes while analyzing the influencing factors.

Patients and Methods

A retrospective cohort study comprised 4839 patients who underwent their first cycle of IVF/ICSI treatment from January 2016 to December 2021. Cumulative pregnancy rates, cumulative live birth rates, and late miscarriage rates compared between the PCOS group and control group. Subgroup analysis and binary regression were used to analyze the influence of BMI on clinical outcomes among individuals diagnosed with PCOS.

Results

Non-obese PCOS patients exhibited higher cumulative pregnancy rates, cumulative live birth rates, and late miscarriage rates compared to the control group with the normal BMI population (84.7% vs71.2%, P < 0.001; 74.1% vs 61.6%, P < 0.001; 4.1% vs 2.0%, P = 0.002), but there was no significant difference in early miscarriage rates between the two groups.

Conclusion

Non-obese PCOS patients demonstrated a notably higher cumulative live birth rate but also a higher risk of late miscarriage compared to non-PCOS females with a normal BMI.

Polycystic ovary syndrome and adverse pregnancy outcomes: potential role of decidual function

Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting fertility and mental health among women of reproductive age. In addition to anovulation and hyperandrogenism, patients also experience metabolic issues, such as insulin resistance, obesity, and dyslipidemia, as well as chronic low-grade inflammation throughout the body. Recent studies have shown that even with assisted reproductive technology to treat anovulatory issues, patients with PCOS still have higher rates of adverse pregnancy outcomes and abortion compared to normal pregnancies. These findings suggest that PCOS may impair the endometrium and disrupt the onset and maintenance of healthy pregnancies. Decidualization is a crucial step in the process of healthy pregnancy, during which endometrial stromal cells (ESCs) differentiate into secretory decidual stromal cells (DSCs) regulated by hormones and local metabolism. This article comprehensively reviews the pathological processes of PCOS and the mechanisms involved in its impaired decidualization. In addition, we explore how PCOS increases the incidence of adverse pregnancy outcomes (APO). By gaining a better understanding of the adverse effects of PCOS on pregnancy and its specific mechanisms, we hope to provide a theoretical basis for reducing APO and improving the live birth rate among women with PCOS.

Association between maternal polycystic ovarian syndrome undergoing assisted reproductive technology and pregnancy complications and neonatal outcomes: a systematic review and meta-analysis

BACKGROUND

Polycystic ovarian syndrome (PCOS) is recognized as the most prevalent endocrine disorder among women of reproductive age. While the utilization of assisted reproductive technology (ART) has resulted in favorable outcomes for infertility treatment in PCOS patients, the inherent pathophysiological features of the condition give rise to complications and consequences during pregnancy and delivery for both the mother and offspring. This study was to assess the correlation between maternal PCOS and various pregnancy complications and neonatal outcomes undergone ART.

METHODS

A systematic search was conducted on PubMed, EmBase, and the Cochrane Library to identify observational studies that investigated the association between PCOS and the risk of various pregnancy complications and neonatal outcomes, including gestational diabetes mellitus (GDM), hypertension in pregnancy (PIH), preeclampsia (PE), preterm birth, abortion, congenital malformations (CA), small for gestational age (SGA), large for gestational age (LGA), low birth weight (LBW), macrosomia, neonatal intensive care unit (NICU) admission and birth weight. Eligible studies were selected based on predetermined inclusion and exclusion criteria. The meta-analysis was conducted using Review Manager and Stata software, with odds ratios (ORs) or mean difference (MD), confidence intervals (CIs), and heterogeneity (I2) being calculated. The search was conducted up to March 2023.

RESULTS

A total of 33 studies with a combined sample size of 92,810 participants were identified. The findings indicate that PCOS is significantly associated with an increased risk of GDM (OR 1.51, 95% CI:1.17-1.94), PIH (OR 1.72, 95% CI:1.25-2.39), PE (OR 2.12, 95% CI:1.49-3.02), preterm birth (OR 1.29, 95% CI:1.21-1.39), and LBW (OR 1.29, 95% CI:1.14-1.47). In subgroup analyses, the risks of GDM (OR 1.80, 95% CI:1.23-2.62) and abortion (OR 1.41, 95% CI:1.08-1.84) were elevated in fresh embryo transferred (ET) subgroup, whereas elevated risk of PE (OR 1.82, 95% CI:1.17-2.83) and preterm birth (OR 1.31, 95% CI:1.21-1.42) was identified in frozen ET subgroup. Whatever with or without hyperandrogenism, patients with PCOS had a higher risk in preterm birth (OR 1.69, 95% CI: 1.31-2.18; OR 1.24, 95% CI:1.02-1.50) and abortion (OR 1.38, 95% CI:1.12-1.71; OR 1.23, 95% CI:1.06-1.43).

CONCLUSION

Our findings suggest that individuals with PCOS undergone ART are at a notably elevated risk for experiencing pregnancy complications and unfavorable neonatal outcomes. Nevertheless, to establish a definitive association between PCOS and pregnancy-related outcomes, it is necessary to conduct extensive prospective, blinded cohort studies and effectively control for confounding variables.

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 influence of polycystic ovary syndrome on abortion rate after in vitro fertilization/intracytoplasmic sperm injection fresh cycle pregnancy

There are many reports on clinical pregnancy outcomes in polycystic ovary syndrome (PCOS) patients receiving vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI), but little research about abortion has been done and there is a debate on whether the abortion risk increases in PCOS patients receiving IVF/ICSI. Therefore, the aim of this study was to investigated the abortion in PCOS patients. Clinical data of 12055 IVF/ICSI fresh cycles performed in our hospital from January 2015 to December 2020 were collected. Based on the Rotterdam diagnostic criteria of PCOS and after propensity score matching (PSM) for baseline data of clinical pregnancy cycles, matched 599 PCOS (PCOS group) and Non-PCOS (non-PCOS group) cycles were obtained. Abortion and abortion-related outcomes were compared between the two groups. Risk factors for late abortion in twins were analyzed using binary Logistics regression. Post-PSM data showed that the late abortion rate was significantly higher in the PCOS group than in the non-PCOS group only in twin pregnancy (9.50% vs. 3.96%, OR: 2.55, 95%CI 1.10-5.89). There were no statistical differences in other pregnancy outcomes. The etiological distribution for late abortion were not statistically different between the two groups in both singletons and twins. Logistics regression indicated that PCOS and obesity [pregnancy-assisted body mass index (BMI) ≥ 28] were risk factors for late abortion in twin pregnancy. In twin pregnancy, PCOS and obese patients are more likely to have late abortion. In twin pregnancy, the late abortion risk significantly increased in the PCOS patients as compared with non-PCOS patients (OR: 2.59, 95%CI 1.11-6.03, P < 0.05), as well as in the patients with obesity (BMI ≥ 28) as compared with the patients with normal BMI (OR: 4.17, 95%CI 1.59-10.90, P < 0.05). PCOS does not significantly affect early and overall late abortion rates after IVF/ICSI fresh cycle pregnancy.

Overweight and obesity affect the efficacy of vaginal vs. intramuscular progesterone for luteal-phase support in vitrified-warmed blastocyst transfer

OBJECTIVE

To compare the difference in the live birth rates (LBRs) between vaginal progesterone and intramuscular progesterone as luteal-phase support in programmed vitrified-warmed blastocyst transfer cycles and determine whether the association was moderated by overweight/obesity.

DESIGN

Retrospective cohort study.

SETTING

Tertiary reproductive medicine center.

PATIENT(S)

Patients who underwent transfer of single vitrified-warmed blastocyst in a programmed cycle between January 2018 and June 2021.

INTERVENTION(S)

Vaginal or intramuscular progesterone as luteal-phase support. Analysis was performed using the generalized estimating equation framework and multivariate regression models. Interaction testing was used to determine whether overweight/obesity (body mass index of ≥25 kg/m²) moderated the association between progesterone replacement and LBRs.

MAIN OUTCOME MEASURE(S)

The primary outcome was live birth. The secondary outcomes were biochemical pregnancy, clinical pregnancy, miscarriage, and total pregnancy loss.

RESULT(S)

A total of 6,905 programmed cycles (4,616 with vaginal progesterone and 2,289 with intramuscular progesterone) were included in the analysis. In the general cohort who underwent cryopreserved blastocyst transfer, the LBRs were 46.23% and 48.62% in the vaginal and intramuscular progesterone groups, respectively (odds ratio [OR], 0.91; 95% confidence interval [CI], 0.82-1.01; adjusted OR [aOR], 0.89; 95% CI, 0.81-0.98), with a significantly increased rate of pregnancy losses in the vaginal progesterone group compared with that in the intramuscular progesterone group (22.22% vs. 18.90%; OR, 1.23; 95% CI, 1.08-1.39; aOR, 1.23; 95% CI, 1.08-1.40). Among normal-weight women, the LBR in the vaginal progesterone group was lower than that in the intramuscular progesterone group (aOR, 0.84; 95% CI, 0.75-0.95). On the other hand, among women with overweight/obesity, the LBRs were similar between the 2 groups of progesterone replacement (aOR, 1.06; 95% CI, 0.86-1.33). Interaction testing of the routes of progesterone administration and overweight/obesity was significant.

CONCLUSION(S)

Luteal-phase support with vaginal progesterone was associated with reduced LBRs compared with intramuscular progesterone for vitrified-warmed blastocyst transfer, and the association was modified by maternal overweight/obesity. Further research is needed to better understand the mechanisms behind the association.

Pregnancy outcomes in patients with polycystic ovary syndrome who conceived after single thawed blastocyst transfer: a propensity score-matched study

Background

It remains unclear whether polycystic ovary syndrome (PCOS) is an independent risk factor for pregnancy complications in women undergoing assisted reproductive technology (ART) treatment. For the integrative treatment of PCOS patients, it is still important to investigate the pregnancy outcomes of PCOS patients after adjusting for potential biases, such as body mass index, embryo quality and endometrial preparation method.

Methods

This retrospective cohort study ultimately included a total of 336 PCOS patients who conceived after single thawed blastocyst transfer in the PCOS group and 2,325 patients in the control group from January 2018 to December 2020. A propensity score matching (PSM) model was used, and 336 PCOS patients were matched with 336 patients in the control group.

Results

Before PSM, no differences in the miscarriage rate, pregnancy complication rate, preterm birth rate, or live birth rate were found between the PCOS group and the control group. After PSM, the late miscarriage rate of the PCOS group was significantly higher than that of the control group (3.3% vs. 0.6%, P = 0.040), although the early miscarriage rates were similar (14.0% vs. 13.7%). The rates of pregnancy complications, preterm birth and live birth in the PCOS group were comparable to those in the matched control group (P = 0.080, P = 0.105, P = 0.109, respectively). The neonatal weights of male infants and female infants were similar between the two groups (P = 0.219, P = 0.169). Subgroup analysis showed that PCOS patients with homeostasis model assessment of insulin resistance (HOMA-IR) levels ≥ 2.49 had a significantly increased risk of preterm birth compared with those with HOMA-IR levels < 1.26 and 1.26 ≤ HOMA-IR levels < 2.49 (26.0% vs. 6.0% vs. 9.8%, P = 0.005). PCOS patients with total testosterone levels ≥ 0.7 ng/ml had a higher early miscarriage rate but a lower late miscarriage rate than those with total testosterone levels < 0.7 ng/ml (29.4% vs. 12.3%, 0% vs. 3.6%, respectively, P = 0.032).

Conclusions

PCOS is an independent risk factor for late miscarriage in patients conceived after a single thawed blastocyst transfer, even after adjusting for biases. Among PCOS patients, insulin resistance and hyperandrogenism are associated with a higher risk of preterm birth and early miscarriage, respectively.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-05011-4.

Clinical management of pregnancy in women with polycystic ovary syndrome: An expert opinion

Polycystic ovary syndrome (PCOS) is associated with a higher risk for pregnancy and birth complications according to the specific features associated with PCOS. The features include obesity before and during pregnancy, hyperandrogenism, insulin resistance, infertility, cardiometabolic risk factors, and poor mental health. PCOS is not often recognized as a risk factor for poor pregnancy and birth outcomes in pregnancy care guidelines, while its associated features are. Pregnancy-related risk profile should ideally be assessed for modifiable risk factors (e.g., lifestyle and weight management) at preconception in women with PCOS. Hyperglycaemia should be screened using a 75-g oral glucose tolerance test at preconception or within the first 20 weeks of pregnancy if it has not been performed at preconception and should be repeated at 24-28 weeks of pregnancy. In the absence of evidence of benefit for strategies specific to women with PCOS, the international evidence-based guidelines for the assessment and management of PCOS recommend screening, optimizing, and monitoring risk profile in women with PCOS (at preconception, during and postpregnancy) consistent with the recommendations for the general population. Recommended factors include blood glucose, weight, blood pressure, smoking, alcohol, diet, exercise, sleep and mental health, emotional, and sexual health among women with PCOS. The guidelines recommend Metformin in addition to lifestyle for assisting with weight management and improving cardiometabolic risk factors, particularly in those with overweight or obesity. Letrozole is considered the first-line pharmacological treatment for anovulatory infertility in PCOS. Individualized approach should be considered in the management of pregnancy in PCOS.

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.

Effects of Acupuncture on Endometrium and Pregnancy Outcomes in Patients with Polycystic Ovarian Syndrome Undergoing In Vitro Fertilization-Embryo Transfer: A Randomized Clinical Trial

OBJECTIVE

To observe the effect of acupuncture on endometrium and pregnancy outcomes in patients with polycystic ovary syndrome (PCOS) infertility undergoing in vitro fertilization-embryo transfer (IVF-ET).

METHODS

Eighty-three patients were randomly assigned to observation group (40 cases) and control group (43 cases) according to the random numbers generated by SPSS software. The patients of the two groups received GnRH agonist long protocol as a routine treatment. In the observation group, acupuncture was given at two acupoint groups for 30 min once every other day. Group 1 included Guanyuan (CV 4), Qihai (CV 6), Zhongji (CV 3), bilateral acupoints Zigong (EX-CA1). Group 2 included Mingmen (GV 4), Yaoyangguan (GV 3), bilateral Shenshu (BL 23) and Ciliao (BL 32). The two groups of acupoints were used alternately. The whole needling process was performed at the time of ovulation induction until the transplantation day and consisted of 3 courses, while the control group did not receive acupuncture interventions. The Gn dosage and Gn stimulation time, endometrial thickness and type (A, B, and C), serum oestradiol (E2) and progesterone (P) levels on the day of injection of human chorionic gonadotropin (hCG), clinical pregnancy rate, as well as live birth rate were observed. Adverse reactions were also be recorded. All patients were followed up for the pregnant rate 14 days after IVF-ET and live birth rate after pregnancy. All adverse reactions (AEs) of acupuncture were recorded during the trial.

RESULTS

The Gn dosage and Gn stimulation time in the observation group were lower in the observation group than in the control group (P<0.01). The proportion of type A endometrium in the observation group were higher than that in the control group (P<0.05). The serum E₂ and P levels on the day of hCG injection was lower and the clinical pregnancy rate was higher in the observation group compared to those in the control group (P<0.05). There was no serious AEs during this trial.

CONCLUSION

Acupuncture can improve the proportion of type A endometrium, regulate the levels of serum E₂ and P on the day of hCG injection, and improve the pregnancy rate in patients with PCOS infertility undergoing IVF-ET.

Early Spontaneous Abortion in Fresh- and Frozen-Embryo Transfers: An Analysis of Over 35,000 Transfer Cycles

BACKGROUND

The aim of this study was to explore the risk factors for early spontaneous abortion (ESA) in fresh- and frozen-embryo transfers.

METHODS

This retrospective cohort study comprised a total of 35,076 patients, including 15,557 women in the fresh-embryo transfer group and 19,519 women in the frozen-embryo transfer group from January 2016 to December 2020. The primary outcome of this study was ESA, which we defined as the termination of embryonic development before 12 weeks of pregnancy (i.e., an early abortion after artificial multi-fetal pregnancy reduction was excluded).

RESULTS

In the 35,076 ART transfer cycles, the incidence of ESA was 5.77% (2023/35,076), and the incidence rates for ESA in fresh and frozen cycles were 4.93% (767 of 15,557) and 6.43% (1,256 of 19,519), respectively. Using a multivariate logistic regression analysis model, maternal age, body mass index (BMI), and number of embryos transferred were independent predictors for ESA. In addition, frozen-thawed transfer was a risk factor for ESA as compared with fresh transfer (OR = 1.207; 95% CI, 1.094-1.331; P = 0.000), blastocyst transfer was risk factor for ESA as compared with cleavage transfer (OR =1.373; 95% CI, 1.186-1.591; P = 0.000 in the total group; OR = 1.291; 95% CI, 1.111-1.499; P = 0.001 in the frozen-transfer group), and unexplained infertility was a protective factor for ESA only in the frozen group (OR = 0.746; 95% CI, 0.565-0.984; P = 0.038).

CONCLUSIONS

Maternal age, BMI, number of embryos transferred, and frozen-thawed transfer were independent risk factors for ESA in assisted reproductive technology treatment cycles.

Suppression of uterine and placental ferroptosis by N-acetylcysteine in a rat model of polycystic ovary syndrome

The mechanisms that link hyperandrogenism and insulin (INS) resistance (HAIR) to the increased miscarriage rate in women with polycystic ovary syndrome (PCOS) remain elusive. Previous studies demonstrate that increased uterine and placental ferroptosis is associated with oxidative stress-induced fetal loss in a pre-clinical PCOS-like rat model. Here, we investigated the efficacy and molecular mechanism of action of the antioxidant N-acetylcysteine (NAC) in reversing gravid uterine and placental ferroptosis in pregnant rats exposed to 5α-dihydrotestosterone (DHT) and INS. Molecular and histological analyses showed that NAC attenuated DHT and INS-induced uterine ferroptosis, including dose-dependent increases in anti-ferroptosis gene content. Changes in other molecular factors after NAC treatment were also observed in the placenta exposed to DHT and INS, such as increased glutathione peroxidase 4 protein level. Furthermore, increased apoptosis-inducing factor mitochondria-associated 2 mRNA expression was seen in the placenta but not in the uterus. Additionally, NAC was not sufficient to rescue DHT + INS-induced mitochondria-morphological abnormalities in the uterus, whereas the same treatment partially reversed such abnormalities in the placenta. Finally, we demonstrated that NAC selectively normalized uterine leukemia inhibitory factor, osteopontin/secreted phosphoprotein 1, progesterone receptor, homeobox A11 mRNA expression and placental estrogen-related receptor beta and trophoblast-specific protein alpha mRNA expression. Collectively, our data provide insight into how NAC exerts beneficial effects on differentially attenuating gravid uterine and placental ferroptosis in a PCOS-like rat model with fetal loss. These results indicate that exogenous administration of NAC represents a potential therapeutic strategy in the treatment of HAIR-induced uterine and placental dysfunction.

Comparison of Stimulated Cycles with Low Dose r-FSH versus Hormone Replacement Cycles for Endometrial Preparation Prior to Frozen-Thawed Embryo Transfer in Young Women with Polycystic Ovarian Syndrome: A Single-Center Retrospective Cohort Study from China

Objective

The principal purpose of this study was to compare reproductive outcomes for stimulated cycles (STC) and hormone replacement cycles (HRC) for endometrial preparation before frozen-thawed embryo transfer (FET) in young women with polycystic ovary syndrome (PCOS).

Methods

We conducted a retrospective study of 1434 FET cycles from January, 2017 to March, 2020 in our reproductive center, in which stimulated and hormone replacement cycles were used for endometrial preparation. Pregnancy outcomes of couples undergoing routine STC-FET or HRC-FET were analyzed by propensity score matching (PSM) and multivariable logistic regression analyses.

Results

Data on 1234 HRC protocols (86% of the total) and 200 STC protocols (14%) were collected. After PSM, 199 patients were included in both groups, respectively. There was no significant difference in positive pregnancy rate (52.7% vs 54.8%, p=0.763), clinical pregnancy rate (51.8% vs 52.8%, p=0.841), live birth rate (45.2% vs 43.7%, p=0.762), pregnancy loss rate (9.7% vs 16.2%, p=0.164) and ectopic pregnancy rate (1.5% vs 0.5%, p=0.615) between STC and HRC protocols. Subsequent multivariate logistic regression analysis also yielded similar results.

Conclusion

STC for endometrial preparation had similar pregnancy outcomes compared with HRC protocols. Evidence is available which shows that for young women with PCOS in preparation for FET, HRC could be a reasonable choice for patients who are unwilling to accept injections. However, STC may reduce unnecessary anxiety and operational costs and offer more flexibility for patients. Eventually, we must embrace the concepts of individualization, securitization, and optimization in the clinic.