Thalassemia, a common autosomal recessive genetic disorder prevalent in regions such as the Mediterranean, Southeast Asia, and the Middle East, includes α-thalassemia and β-thalassemia, both caused by defects in α-globin or β-globin chain synthesis, leading to anemia and iron overload (Langer et al., 1993; Tamary et al., 1993). Women affected by thalassemia often face reproductive health issues, such as chronic anemia and premature ovarian insufficiency (Tsilionis et al., 2024). Despite the significant impact of thalassemia on maternal health, most research has focused on transfusion management, obstetric complications, and fetal risks (Ruangvutilert et al., 2023; Li et al., 2025), with limited studies on how thalassemia carrier status might affect embryo health, specifically embryo euploidy and developmental competence during in vitro fertilization (IVF). This gap in knowledge highlights the need for further exploration, especially in the context of advancements in preimplantation genetic testing (PGT).

Over the past few decades, substantial advancements in PGT—from initially screening single-gene disorders (PGT-M) to detecting polygenic conditions and chromosomal abnormalities (PGT-A)—alongside improvements in embryo culture techniques such as blastocyst culture and vitrification, have significantly transformed modern in vitro fertilization (IVF). These technological advancements have enabled more precise embryo screening and selection, subsequently increasing clinical pregnancy rates and the probability of healthy live births. Consequently, the focus of patient counseling has shifted from merely achieving embryo transfer (ET) toward selecting embryos with the highest potential for healthy live births and minimal risk of complications (Ubaldi et al., 2019).

PGT-A is primarily indicated for patients with advanced maternal age or recurrent pregnancy loss (Rubio et al., 2013; Coonen et al., 2020). Numerous studies have documented that maternal age is a key determinant of embryo aneuploidy and reproductive outcomes (Franasiak et al., 2014). Recent research has further explored differences in embryo chromosomal abnormalities and embryo availability between IVF cycles employing combined PGT-M and PGT-A versus cycles using PGT-A alone (Stocker et al., 2022; Martel et al., 2024). However, while the combined use of PGT-A and PGT-M has increasingly been studied, existing literature primarily addresses embryo euploidy rates in general IVF populations, with limited systematic investigation into embryo euploidy outcomes among women with specific genetic disorders.

Given these technological advances, it remains unclear whether women with specific genetic disorders—such as thalassemia—experience differences in embryo chromosomal status or developmental potential during IVF. Women affected by thalassemia often suffer from chronic anemia and iron overload, potentially leading to premature ovarian insufficiency and endocrine dysfunction (Skordis et al., 2006; Ahmed et al., 2022). Despite these reproductive health implications, current thalassemia research mainly addresses transfusion management, obstetric complications, and fetal risks during pregnancy (Adler et al., 2021; Nassar et al., 2006; Charoenboon et al., 2016). Systematic data examining how thalassemia carrier status affects embryo euploidy, developmental competence, and embryo availability in IVF cycles utilizing PGT-A remain scarce.

Women with thalassemia face unique counseling challenges in assisted reproductive treatments, particularly regarding embryo health and genetic risks. Effective counseling significantly influences patient decision-making at all stages of treatment, ultimately impacting successful conception outcomes. Therefore, this study aimed first to evaluate differences in embryo euploidy rates between women with and without thalassemia undergoing IVF with PGT-A. Secondly, we assessed the likelihood of obtaining at least one transferable embryo between these two groups, stratified by maternal age, to better inform clinical practice and patient counseling.

All patients included in this study underwent standardized ovarian stimulation protocols established at our institution. Specific stimulation regimens, primarily involving GnRH antagonist or GnRH agonist protocols, were individualized by the attending physician based on ovarian reserve, patient age, and previous treatment responses. Follicular growth was monitored using transvaginal ultrasonography (7.5-MHz transvaginal probe, GE Voluson S10, United States), combined with serum measurements of estradiol (E2), luteinizing hormone (LH), and progesterone (P). Ovulation trigger was administered when at least two leading follicles reached a diameter of 17–18 mm (extended to 20–24 mm in letrozole or clomiphene cycles). Human chorionic gonadotropin (hCG), GnRH agonist (GnRH-a), or a combination of both was selected individually for triggering ovulation. Oocyte retrieval was conducted via transvaginal ultrasound approximately 35–37 h after the trigger. Intracytoplasmic sperm injection (ICSI) was primarily used to reduce the risk of DNA contamination when PGT was planned prior to fertilization, while conventional IVF was also performed in cases where PGT-A was added after fertilization based on patient preference. Fertilization was assessed on day 1 post-retrieval, with embryo morphology evaluated on days 3 and 5.

A total of 2,110 women were included in this study, comprising 1,155 women without thalassemia and 955 women with thalassemia. Significant differences were observed between the two groups regarding age, BMI, AMH levels, ovarian stimulation protocols, and number of retrieved oocytes (Table 1). Women without thalassemia had a significantly higher median age [39 years (interquartile range, IQR: 37–41)] compared to those with thalassemia [34 years (IQR: 30–38), p < 0.001]. BMI was significantly lower in the thalassemia group [21.64 (IQR: 19.99–23.60) vs. 22.48 (IQR: 20.81–24.84), p < 0.001]. Additionally, AMH levels were significantly higher among women with thalassemia [2.58 ng/mL (IQR: 1.59–4.28) vs. 1.99 ng/mL (IQR: 1.12–3.32), p < 0.001]. Genetic factors were the primary cause of infertility in women with thalassemia (72.7%), whereas diminished ovarian reserve (DOR) was predominant among women without thalassemia (46.3%, p < 0.001). Furthermore, women with thalassemia more frequently used GnRH agonist protocols (39.7% vs. 29.7%, p < 0.001) and had significantly higher numbers of retrieved oocytes, mature oocytes, and fertilized oocytes (all p < 0.001).

Table 2 presents embryo biopsy and euploidy outcomes. Women with thalassemia had significantly more biopsied blastocysts [median 5 (IQR: 3–7)] compared to controls [median 3 (IQR: 2–5)], with a significantly higher unadjusted relative risk (RR = 1.32, 95% CI: 1.27–1.38). However, after adjustment for age, BMI, AMH, ICSI, infertility diagnosis, stimulation protocol, total gonadotropin dose, oocytes retrieved, mature oocytes, and fertilized oocytes, this difference became non-significant (adjusted RR = 1.06, 95% CI: 0.99–1.13). Similarly, the median number of euploid embryos was higher in women with thalassemia [2 (IQR: 1–4)] compared to controls [1 (IQR: 0–2)] in unadjusted analyses (RR = 1.91, 95% CI: 1.79–2.04), yet was not significant after adjustment (adjusted RR = 0.96, 95% CI: 0.86–1.08). The median proportion of euploid embryos was higher in women with thalassemia (0.50, IQR: 0.20–0.67) compared to controls (0.25, IQR: 0–0.50); however, this difference lost statistical significance after adjustment (adjusted β = −0.03, 95% CI: −0.07–0.01). The age-stratified proportion of patients with at least one euploid embryo is displayed in Figure 1. Supplementary Figures S1, S2 illustrate the distribution of cycles without any usable embryos and with all embryos usable, respectively.

Table 3 summarizes age-stratified embryo euploidy outcomes. Among women younger than 35 years, median counts were similar (both 5), but the distribution favored the thalassemia group (unadjusted RR = 1.08, 95% CI: 1.02–1.15), which was not significant after adjustment (adjusted RR = 1.08, 95% CI: 0.96–1.22). Similar patterns were observed for euploid embryos (unadjusted RR = 1.21, 95% CI: 1.11–1.32; adjusted RR = 0.96, 95% CI: 0.81–1.14). No significant difference was found in median euploid proportions (both 0.50, adjusted β = −0.02, 95% CI: −0.10 to 0.06). Women aged 35–40 years showed no significant differences in embryo biopsy or euploid embryo numbers, but a slightly lower euploid proportion was observed in the thalassemia group, becoming significant after adjustment (adjusted β = −0.07, 95% CI: −0.13 to −0.01). No significant differences emerged in women aged over 40 years Supplementary Table S1 indicated a significant negative interaction between thalassemia status and infertility categorized as “other” (β = −0.103, p = 0.033), suggesting the underlying infertility diagnosis may influence euploidy outcomes.

A post hoc subgroup analysis limited to the first PGT-A cycles per patient confirmed the primary findings, revealing no significant differences in biopsied blastocysts (adjusted RR = 1.04, 95% CI: 0.97–1.12), euploid embryo numbers (adjusted RR = 0.92, 95% CI: 0.81–1.04), or euploid proportion (adjusted β = −0.04, 95% CI: −0.08 to 0). No significant interaction was found regarding the first PGT-A cycle (β = 0.072, p = 0.058).

This study is a large-scale, single-center registry-based cohort analysis aimed at comparing the euploidy rates between women with thalassemia and those without undergoing autologous IVF cycles combined with PGT-A. After adjustment for critical covariates such as age, BMI, and AMH, no significant differences in embryo euploidy outcomes were observed between thalassemia and control groups, suggesting that the initially higher unadjusted euploid counts in the thalassemia group were largely explained by differences in baseline characteristics. These adjusted results provide the most accurate interpretation of the data and form the basis of our clinical conclusions. Further subgroup analysis revealed a slightly lower euploidy proportion among thalassemia women aged 35–40 years, but no significant differences were observed in other age groups.

A systematic review involving 26 small-scale studies reported a reduction in transferable embryos from 57.5% to 37.2% following the addition of PGT-A to PGT-M, highlighting the potential increased risk of cycles without transferable embryos (Toft et al., 2020). Similarly, Stocker et. Demonstrated a decrease in embryo suitability for transfer from 69% to 41% when incorporating PGT-A into PGT-M treatment for autosomal recessive disorders (Stocker et al., 2022). Given that embryo availability relates not only to pathogenicity but also to euploidy, the reduced number of embryos available for transfer when utilizing more precise selection methods is unsurprising. It remains critical to consider whether the presence of single-gene disorders itself impacts embryo aneuploidy rates. Martel et al. further reported significantly lower rates of usable embryos among women under 37 years undergoing PGT-M compared to those receiving only PGT-A, though no significant differences in aneuploidy rates were found (Martel et al., 2024). These findings align with our observations, which indicated no significant association between thalassemia status and embryo euploidy rates. Nonetheless, the Martel et al. study had limitations, including the failure to explicitly exclude patients with single-gene disorders from the PGT-A-only group and the lack of stratified analysis by inheritance patterns or adequate adjustment for critical covariates such as age, BMI, and AMH (Martel et al., 2024). In contrast, our study focused explicitly on an autosomal genetic disorder—thalassemia—and excluded control participants and their partners who could potentially carry other genetic or hematologic conditions, thereby minimizing confounding factors. Moreover, we meticulously adjusted for multiple reproductive covariates such as age, BMI, and AMH levels, ensuring the robustness and reliability of our results. Subgroup analyses across various age ranges further demonstrated no substantial association between thalassemia and non-thalassemia women regarding embryo euploidy, particularly among groups younger than 35 years and older than 40 years.

Previous literature has suggested that oocyte quality significantly influences susceptibility to chromosomal segregation errors (Demyda-Peyrás et al., 2013). In women with thalassemia, iron overload leads to accumulation of non-transferrin-bound iron (NTBI) in ovarian tissues, which generates reactive oxygen species (ROS) via the Fenton reaction, inducing oxidative stress and damaging ovarian cells, potentially impairing oocyte developmental potential (Tsilionis et al., 2024). Furthermore, iron overload and oxidative stress disrupt hepatic and pancreatic functions, affecting hormone metabolism, exacerbating endocrine imbalances, and indirectly impairing the ovarian microenvironment, ultimately influencing oocyte quality (Singer et al., 2011; Castaldi and Cobellis, 2016). However, overall, women with thalassemia showed comparable chances of obtaining at least one euploid embryo compared to non-thalassemia women, with only minimal differences observed after adjustment. Small age-related variations were noted, with a slightly lower adjusted euploid proportion among women aged 35–40 years, whereas younger women showed similar or marginally higher euploid embryo counts. This mild decrease in the 35–40-year group may reflect the cumulative effects of chronic anemia–related oxidative stress, subtle age-associated declines in oocyte competence, and the increased metabolic demands of folliculogenesis in mid-reproductive age. Clinically, these findings suggest that women with thalassemia in this age range may benefit from more proactive counseling regarding expected embryo availability and the potential need for multiple stimulation cycles.

While this observation may partly reflect the younger age and better ovarian reserve parameters in the thalassemia group, the absence of significant differences in euploid outcomes after multivariable adjustment suggests that thalassemia itself does not impair, and may even preserve, chromosomal competence during embryo development. Mensia et al. similarly found no significant impairment in oocyte quality among women with thalassemia, despite lower ovarian reserves (Mensi et al., 2019). Our team’s previous research indicated that women with non-transfusion-dependent thalassemia exhibited superior oocyte maturity and fertilization outcomes compared to carriers, despite comparable baseline conditions (Fan et al., 2025). These observations suggest that thalassemia women might represent a systemic “low-risk phenotype,” analogous to observations in neurological and cardiovascular systems (Fallahzadeh et al., 2009; Dentali et al., 2011), though this hypothesis warrants further investigation.

A potential explanation for our findings could relate to differences in the reasons for seeking assisted reproductive treatments between thalassemia and non-thalassemia women, along with the generally younger age of the thalassemia group. These factors could influence embryo quality and euploidy outcomes. Previous studies also indicate that certain infertility conditions, such as recurrent pregnancy loss or previous IVF failures, typically exhibit lower euploidy rates compared to fertile populations (Kort et al., 2018). Therefore, thalassemia women may exhibit a tendency toward higher numbers of biopsied and euploid embryos. Nonetheless, after adjustment for covariates including age, BMI, and AMH, these differences were not statistically significant. Notably, the slightly higher proportion of women with thalassemia obtaining at least one euploid embryo may relate to higher fetal hemoglobin (Hb F) levels and lower LDL levels typically observed in these patients. Elevated Hb F levels effectively facilitate oxygen transport in hypoxic conditions (Ibrahim et al., 2009), and lower LDL concentrations have been positively associated with higher embryo quality and may indirectly enhance embryo implantation capacity (Wang et al., 2020; Herz et al., 1992).

This study’s strengths include being the first extensive investigation into PGT-A outcomes specifically in a thalassemia population, providing valuable empirical data on reproductive outcomes for these patients. All biopsy cycles were performed in the same laboratory, ensuring internal consistency and reliability. Our findings offer important clinical insights that aid physicians in counseling thalassemia patients and setting realistic expectations, fostering better physician-patient relationships. However, several limitations exist. First, retrospective data collection may introduce selection bias and data completeness issues, with incomplete control over all confounding factors. Although multivariable regression models, age-stratified analyses, and AMH interaction analyses were employed to adjust for key factors such as age and ovarian reserve, inherent differences in the clinical indications between the thalassemia and non-thalassemia groups—primarily genetic versus DOR/AMA—may still result in residual confounding. Notably, most thalassemia patients underwent IVF for genetic reasons rather than infertility; however, our study specifically aimed to assess whether thalassemia-related physiological factors affect embryonic chromosomal integrity during PGT-A, rather than reproductive potential itself. In addition, as many patients were referred from external centers after genetic screening, detailed genotype information (e.g., α-vs. β-thalassemia, or carrier vs. affected status) was not consistently documented. Second, as a single-center study, the generalizability of our findings might be limited, necessitating future multi-center studies for broader applicability validation. Lastly, clinical outcome data post-embryo transfer was not included, restricting the evaluation of actual improvements in clinical outcomes for thalassemia patients after euploid embryo transfer. Future studies should consider including clinical outcomes to further enhance understanding in this area.

In conclusion, while women with thalassemia exhibited higher unadjusted euploid embryo counts, these differences were not significant after adjustment for age, BMI, and AMH. A mild but statistically significant reduction in euploid proportion was observed only among women aged 35–40 years. Overall, thalassemia does not appear to impair embryonic chromosomal integrity in IVF cycles with PGT-A, but cautious reproductive counseling may be advisable for women within this mid-age group.