1.Different fertilization methods and quality of blastocyst trophoblast may affect the sex ratio at birth in single blastocyst transfer cycles
Zhaocheng ZENG ; Huili JI ; Jiang JIANG ; Jianwen SU ; Meijuan CHEN ; Xuefang WANG ; Ketong SU
Chinese Journal of Reproduction and Contraception 2025;45(5):475-481
Objective:To analyze the effects of fertilization methods, quality of inner cell mass (ICM) and trophectoderm (TE) on the sex ratio at birth (SRB) during single blastocyst transfer cycles.Methods:5 367 single blastocyst transfer cycles in in vitro fertilization/intracytoplasmic sperm injection and embryo transfer (IVF/ICSI-ET) of patients with successful pregnancy and delivery in Reproductive Medical Center of Zhanjiang Jiuhe Hospital from January 2010 to December 2022 were included in this retrospective cohort study. According to different types of embryos, the cycles were divided into fresh embryo group ( n=1 487, total population; n=1 258, ≤35 years old) and frozen-thawed embryo group ( n=3 880, total population; n=3 199, ≤35 years old). According to different fertilization methods, the cycles were divided into IVF group ( n=4 424, total population; n=3 667, ≤35 years old) and ICSI group ( n=943, total population; n=780, ≤35 years old). Chi-square test was used to analyze the differences of SRB among all the patients and the patients aged ≤35 years who underwent different embryo types and fertilization methods, and logistic regression was used to analyze the effects of ICM and TE ratings on SRB in each group of blastocysts. Results:There were 917 male infants (61.7%, 917/1 487) in the fresh embryo transfer group and 2 317 male infants (59.7%, 2 317/3 880) in frozen-thawed embryo transfer group. The SRB of the fresh embryo transfer group (160.9∶100) was slightly higher than that in frozen-thawed embryo transfer group (148.2∶100), but the difference was not statistically significant ( P=0.201). There were 2 732 male infants (61.8%, 2 732/4 424) in IVF group and 502 male infants (53.2%, 502/943) in ICSI group. The SRB of IVF group (161.5∶100) was significantly higher than that of ICSI group (113.8∶100), and the difference was statistically significant ( P<0.001). In female patients aged ≤35 years, the effects of different embryo transfer methods and different fertilization methods on SRB were consistent with the results of total population. Univariate logistic regression analysis showed that the SRB of patients with ICSI was lower than that of patients with IVF, except for 3-6AA. There were significant differences in SRB between ICSI cycles patients (88.8∶100; 72.8∶100; 156.1∶100) and IVF cycles patients (130.7∶100; 124.8∶100; 206.3∶100) when the blastocyst grade was 3-6BB ( OR=0.679, 95% CI: 0.516-0.896, P=0.006), 3-6AB( OR=0.583, 95% CI: 0.421-0.809, P=0.001) and 3-6BA OR=0.757, 95% CI: 0.585-0.979, P=0.034). Taking 3-6BB blastocysts as reference, the SRB of 3-6AA and 3-6BA blastocysts were higher (IVF: OR=1.527, 95% CI: 1.258-1.854, P<0.001; OR=1.579,95% CI: 1.341-1.859, P<0.001; ICSI: OR=2.566, 95% CI: 1.661-3.966, P<0.001; OR=1.758, 95% CI: 1.250-2.472, P=0.001). Compared with 3-6BA, the SRB of 3-6BC blastocysts was lower (IVF: OR=0.621, 95% CI: 0.447-0.862, P=0.004; ICSI: OR=0.442, 95% CI: 0.238-0.818, P=0.009). Taking 3-6AB as reference, the SRB of 3-6AA blastocysts was higher (IVF: OR=1.600, 95% CI: 1.307-1.958, P<0.001; ICSI: OR=3.130, 95% CI: 1.964-4.987, P<0.001). Conclusion:The SRB of fresh embryo group is slightly higher than that of frozen-thawed group in single blastocyst transfer cycles. Different fertilization methods can affect SRB, and the SRB in IVF is significantly higher than that in ICSI group. The quality of blastocysts can affect SRB, and blastocysts with higher quality TE have significantly increased SRB, while ICM quality have no significant effect on SRB.
2.Different fertilization methods and quality of blastocyst trophoblast may affect the sex ratio at birth in single blastocyst transfer cycles
Zhaocheng ZENG ; Huili JI ; Jiang JIANG ; Jianwen SU ; Meijuan CHEN ; Xuefang WANG ; Ketong SU
Chinese Journal of Reproduction and Contraception 2025;45(5):475-481
Objective:To analyze the effects of fertilization methods, quality of inner cell mass (ICM) and trophectoderm (TE) on the sex ratio at birth (SRB) during single blastocyst transfer cycles.Methods:5 367 single blastocyst transfer cycles in in vitro fertilization/intracytoplasmic sperm injection and embryo transfer (IVF/ICSI-ET) of patients with successful pregnancy and delivery in Reproductive Medical Center of Zhanjiang Jiuhe Hospital from January 2010 to December 2022 were included in this retrospective cohort study. According to different types of embryos, the cycles were divided into fresh embryo group ( n=1 487, total population; n=1 258, ≤35 years old) and frozen-thawed embryo group ( n=3 880, total population; n=3 199, ≤35 years old). According to different fertilization methods, the cycles were divided into IVF group ( n=4 424, total population; n=3 667, ≤35 years old) and ICSI group ( n=943, total population; n=780, ≤35 years old). Chi-square test was used to analyze the differences of SRB among all the patients and the patients aged ≤35 years who underwent different embryo types and fertilization methods, and logistic regression was used to analyze the effects of ICM and TE ratings on SRB in each group of blastocysts. Results:There were 917 male infants (61.7%, 917/1 487) in the fresh embryo transfer group and 2 317 male infants (59.7%, 2 317/3 880) in frozen-thawed embryo transfer group. The SRB of the fresh embryo transfer group (160.9∶100) was slightly higher than that in frozen-thawed embryo transfer group (148.2∶100), but the difference was not statistically significant ( P=0.201). There were 2 732 male infants (61.8%, 2 732/4 424) in IVF group and 502 male infants (53.2%, 502/943) in ICSI group. The SRB of IVF group (161.5∶100) was significantly higher than that of ICSI group (113.8∶100), and the difference was statistically significant ( P<0.001). In female patients aged ≤35 years, the effects of different embryo transfer methods and different fertilization methods on SRB were consistent with the results of total population. Univariate logistic regression analysis showed that the SRB of patients with ICSI was lower than that of patients with IVF, except for 3-6AA. There were significant differences in SRB between ICSI cycles patients (88.8∶100; 72.8∶100; 156.1∶100) and IVF cycles patients (130.7∶100; 124.8∶100; 206.3∶100) when the blastocyst grade was 3-6BB ( OR=0.679, 95% CI: 0.516-0.896, P=0.006), 3-6AB( OR=0.583, 95% CI: 0.421-0.809, P=0.001) and 3-6BA OR=0.757, 95% CI: 0.585-0.979, P=0.034). Taking 3-6BB blastocysts as reference, the SRB of 3-6AA and 3-6BA blastocysts were higher (IVF: OR=1.527, 95% CI: 1.258-1.854, P<0.001; OR=1.579,95% CI: 1.341-1.859, P<0.001; ICSI: OR=2.566, 95% CI: 1.661-3.966, P<0.001; OR=1.758, 95% CI: 1.250-2.472, P=0.001). Compared with 3-6BA, the SRB of 3-6BC blastocysts was lower (IVF: OR=0.621, 95% CI: 0.447-0.862, P=0.004; ICSI: OR=0.442, 95% CI: 0.238-0.818, P=0.009). Taking 3-6AB as reference, the SRB of 3-6AA blastocysts was higher (IVF: OR=1.600, 95% CI: 1.307-1.958, P<0.001; ICSI: OR=3.130, 95% CI: 1.964-4.987, P<0.001). Conclusion:The SRB of fresh embryo group is slightly higher than that of frozen-thawed group in single blastocyst transfer cycles. Different fertilization methods can affect SRB, and the SRB in IVF is significantly higher than that in ICSI group. The quality of blastocysts can affect SRB, and blastocysts with higher quality TE have significantly increased SRB, while ICM quality have no significant effect on SRB.

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