Associated factors of secondary sex ratio of offspring in assisted reproductive technology: a cross-sectional study in Jilin Province, China

Assisted reproductive technology induces different secondary sex ratio: parental and embryonic impacts

BACKGROUND

Assisted reproduction technology (ART) has advanced significantly, raising concerns regarding its impact on the secondary sex ratio (SSR), which is the sex ratio at birth in offspring. This study aimed to explore factors affecting SSR in singletons, singletons from twin gestation, and twins from twin gestation within the context of ART.

METHODS

A retrospective analysis was conducted on data from 8335 births involving 6,223 couples undergoing ART. Binary logistic regression assessed relationships between parental and embryonic factors and SSR in singletons and singletons from twin gestation. Multinomial logistic regression models were utilized to identify factors influencing SSR in twins from twin gestation.

RESULTS

Secondary infertility (OR = 1.164, 95% CI: 1.009-1.342), advanced paternal age (OR = 1.261, 95% CI: 1.038-1.534), and blastocyst embryo transfer (OR = 1.339, 95% CI: 1.030-1.742) were associated with an increased SSR, while frozen embryo transfer (FET) showed a negative association with SSR (OR = 0.738, 95% CI: 0.597-0.912) in singletons. A longer duration of gonadotropin (Gn) usage reduced SSR in singletons (OR = 0.961, 95% CI: 0.932-0.990) and singletons from twin gestation (OR = 0.906, 95% CI: 0.838-0.980). In singletons from twin gestation, male-induced infertility (OR = 2.208, 95% CI: 1.120-4.348) and higher Gn dosage (OR = 1.250, 95% CI: 1.010-1.548) were significantly associated with an increased SSR. Women aged > 35 years and intracytoplasmic sperm injection (ICSI) were associated with lower SSR (OR = 0.539, 95% CI: 0.293-0.990 and OR = 0.331, 95% CI: 0.158-0.690, respectively). In twins from twin gestation, paternal age exceeded maternal age (OR = 0.682, 95% CI: 0.492-0.945) and higher Gn dosage (OR = 0.837, 95% CI: 0.715-0.980) were associated with a higher proportion of male twins. Cleavage stage transfer (OR = 1.754, 95% CI: 1.133-2.716) resulted in a higher percentage of boy-girl twins compared to blastocyst transfer.

CONCLUSION

This study demonstrates the complex interplay of various factors in determining the SSR in ART, highlighting the importance of considering infertility type, paternal age, fertilization method, embryo transfer stage, and Gn use duration when assessing SSR. Nevertheless, further research with a large sample size is necessary to confirm and expand upon the findings of this study.

Effect of blastocyst quality on human sex ratio at birth in a single blastocyst frozen thawed embryo transfer cycle

RESEARCH QUESTION

To determine whether blastocyst quality affects the sex ratio at birth through a single blastocyst frozen - thawed embryo transfer (SBFET) cycle.

DESIGN

In this retrospective analysis, we examined 3,041 singleton infants born following SBFET between 2017 and 2020 at a single institution. We compared the sex ratios of these infants with respect to the blastocyst quality, embryo growth rate, and morphology.

RESULTS

The main outcomes of this study were that the sex ratio (M/F) at birth of SBFET was 1.24. Mothers >40 years old had a considerably lower sex ratio than mothers <40 years old (0.39 vs. 1.23-1.28, p < .05). Transplanting high-quality blastocysts significantly increased the proportion of boys born (1.29 vs. 0.88, p < .05). There were no significant differences in the sex ratio with respect to the inner cell mass (ICM) score and expansion degree. Additionally, a high trophoblastic cell (TE) score resulted in a significantly higher sex ratio than the TE score with C (1.62 vs. 1.15 vs. 0.85, p < .001). Multivariable logistic regression analysis was performed to determine which variables were significant factors affecting sex ratio, and the outcomes were consistent with previous findings.

CONCLUSIONS

Our study indicated that high-quality, especially good TE score, had a higher chance of resulting in a male infant than a female infant.

Rhabdoid tumors in patients conceived following ART: is there an association?

STUDY QUESTION

In children affected by rhabdoid tumors (RT), are there clinical, therapeutic, and/or (epi-)genetic differences between those conceived following ART compared to those conceived without ART?

SUMMARY ANSWER

We detected a significantly elevated female predominance, and a lower median age at diagnosis, of children with RT conceived following ART (RT_ART) as compared to other children with RT.

WHAT IS KNOWN ALREADY

Anecdotal evidence suggests an association of ART with RT.

STUDY DESIGN, SIZE, DURATION

This was a multi-institutional retrospective survey. Children with RT conceived by ART were identified in our EU-RHAB database (n = 11/311 children diagnosed between January 2010 and January 2018) and outside the EU-RHAB database (n = 3) from nine different countries. A population-representative German EU-RHAB control cohort of children with RTs conceived without ART (n = 211) (EU-RHAB control cohort) during the same time period was used as a control cohort for clinical, therapeutic, and survival analyses. The median follow-up time was 11.5 months (range 0-120 months) for children with RT_ART and 18.5 months (range 0-153 months) for the EU-RHAB control cohort.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We analyzed 14 children with RT_ART diagnosed from January 2010 to January 2018. We examined tumors and matching blood samples for SMARCB1 mutations and copy number alterations using FISH, multiplex ligation-dependent probe amplification, and DNA sequencing. DNA methylation profiling of tumor and/or blood samples was performed using DNA methylation arrays and compared to respective control cohorts of similar age (n = 53 tumors of children with RT conceived without ART, and n = 38 blood samples of children with no tumor born small for gestational age).

MAIN RESULTS AND THE ROLE OF CHANCE

The median age at diagnosis of 14 individuals with RT_ART was 9 months (range 0-66 months), significantly lower than the median age of patients with RT (n = 211) in the EU-RHAB control cohort (16 months (range 0-253), P = 0.03). A significant female predominance was observed in the RT_ART cohort (M:F ratio: 2:12 versus 116:95 in EU-RHAB control cohort, P = 0.004). Eight of 14 RT_ART patients were diagnosed with atypical teratoid rhabdoid tumor, three with extracranial, extrarenal malignant rhabdoid tumor, one with rhabdoid tumor of the kidney and two with synchronous tumors. The location of primary tumors did not differ significantly in the EU-RHAB control cohort (P = 0.27). Six of 14 RT_ART patients presented with metastases at diagnosis. Metastatic stage was not significantly different from that within the EU-RHAB control cohort (6/14 vs 88/211, P = 1). The incidence of pathogenic germline variants was five of the 12 tested RT_ART patients and, thus, not significantly different from the EU-RHAB control cohort (5/12 versus 36/183 tested, P = 0.35). The 5-year overall survival (OS) and event free survival (EFS) rates of RT_ART patients were 42.9 ± 13.2% and 21.4 ± 11%, respectively, and thus comparable to the EU-RHAB control cohort (OS 41.1 ± 3.5% and EFS 32.1 ± 3.3). We did not find other clinical, therapeutic, outcome factors distinguishing patients with RT_ART from children with RTs conceived without ART (EU-RHAB control cohort). DNA methylation analyses of 10 tumors (atypical teratoid RT = 6, extracranial, extrarenal malignant RT = 4) and six blood samples from RT_ART patients showed neither evidence of a general DNA methylation difference nor underlying imprinting defects, respectively, when compared to a control group (n = 53 RT samples of patients without ART, P = 0.51, n = 38 blood samples of patients born small for gestational age, P = 0.1205).

LIMITATIONS, REASONS FOR CAUTION

RTs are very rare malignancies and our results are based on a small number of children with RT_ART.

WIDER IMPLICATIONS OF THE FINDINGS

This cohort of patients with RT_ART demonstrated a marked female predominance, and a rather low median age at diagnosis even for RTs. Other clinical, treatment, outcome, and molecular factors did not differ from those conceived without ART (EU-RHAB control cohort) or reported in other series, and there was no evidence for imprinting defects. Long-term survival is achievable even in cases with pathogenic germline variants, metastatic disease at diagnosis, or relapse. The female preponderance among RT_ART patients is not yet understood and needs to be evaluated, ideally in larger international series.

STUDY FUNDING/COMPETING INTEREST(S)

M.C.F. is supported by the 'Deutsche Kinderkrebsstiftung' DKS 2020.10, by the 'Deutsche Forschungsgemeinschaft' DFG FR 1516/4-1 and by the Deutsche Krebshilfe 70113981. R.S. received grant support by Deutsche Krebshilfe 70114040 and for infrastructure by the KinderKrebsInitiative Buchholz/Holm-Seppensen. P.D.J. is supported by the Else-Kroener-Fresenius Stiftung and receives a Max-Eder scholarship from the Deutsche Krebshilfe. M.H. is supported by DFG (HA 3060/8-1) and IZKF Münster (Ha3/017/20). BB is supported by the 'Deutsche Kinderkrebsstiftung' DKS 2020.05. We declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.