Serum homocysteine level is an independent risk factor for embryo quality in advanced infertility patient with diminished ovarian reserve: a large sample retrospective study
Authors: Li Jian , Wang Haiyan , Sun Lin , Li Juan , Cao Dan , Zhao Xiaoxuan , He Xinhuan , Jiang Yangyu , Wang Meixian , Xue Xiaoou , Li Beiqing , Shao Xiaoguang 
Published: March 2022

Abstract
Backgrounds: Diminished ovarian reserve (DOR) contributes significantly to female infertility. And embryo quality is one of the decisive factors in the success of pregnancy. However, the factors that influence embryo quality in aged DOR patients are not well established. In this retrospective study, we analyzed the medical records of infertile women with DOR (aged ≥35 years old) who underwent assisted reproductive technique (ART) in our reproductive center to reveal the possible correlation between clinical characteristics and embryo quality. Methods: A total of 1063 infertile patients with DOR and aged ≥35 years old who underwent in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) were selected as subjects in the Reproductive Center of Dalian Medical Women and Children's Medical Center from January 2015 to April 2021. Patients were divided into two groups according to whether they obtained high-quality embryos (N=561 cases) or poor-quality embryos (N=502 cases). The baseline conditions of the 2 groups and the possible influencing factors of embryo quality were compared by Student's t test, Mann-Whitney U test, the chi-square or Fisher’s exact test. Multifactorial binary logistic regression analysis was created to identify statistically significant factors that can affect quality embryos in infertile women with DOR aged ≥35 years old. Finally, all patients were divided into 3 groups according to homocysteine (Hcy) levels, including subgroup A with Hcy ≤ 8 mmol/L, subgroup B with 8＜Hcy ≤15mmol/L and subgroup C with Hcy≥15mmol/L. And general indicators among three groups were compared by one-way anova with Dunnett’s multiple comparisons. And indicators related to embryo quality (number of utilizable embryos and high-quality embryos, the high-quality embryo rate) were compared by chi-square test. Results: A total of 1063 patients with DOR were included, 561 in the high-quality embryo group and 502 in the poor-quality embryo group There was significant difference in infertility years between high-quality embryo group and poor-quality embryo group (P < 0.05) except for female partner's age, male partner's age, BMI, primary and secondary infertility composition ratio, assisted reproduction method, and presence of coeliac disease) (P > 0.05). The result of univariate analysis showed that there were statistically significant differences in the starting dose of Gonadotrophin (Gn), duration of stimulation, the serum level of Hcy, the number of retrieved oocytes, the number of two pronuclei (2PN) and the number of utilizable embryos(D3) (P<0.05). The multi-factor binary regression analysis showed that the level of Hcy [OR 95% CI:0.948(0.898 to 0.999, P<0.05] and duration of stimulation [OR 95% CI:0.939(0.884 to 0.997), P<0.05] were independent risk factors for high-quality embryos. The number of fertilized oocytes (2PN), utilizable embryos (D3) and high-quality embryo (D3) was statistically different among subgroup A, B and C stratified by Hcy concentration (p<0.05). And there was significant difference in the rate of high-quality embryos among three groups stratified by Hcy concentration (P<0.05). The rate of high-quality embryos was significantly lower in subgroup C when compared with subgroup A and B (adjusted P value < 0.05). And there was no difference in the rate of high-quality embryos between subgroup A and subgroup B (adjusted P value >0.05). Conclusions: Our study was the first time to show that serum Hcy levels and duration of stimulation influence the formation of high-quality embryos negatively in aged DOR women, and high Hcy levels (≥15mmol/L) significantly reduce the ratio of high-quality embryos in aged DOR women. Our study reveals for the first time that serum Hcy levels and stimulation duration are independent risk factors for quality embryos in DOR women aged ≥35 years. And, high serum Hcy levels (≥15 mmol/L) can pose a serious threat to aged women with DOR to obtain quality embryos, which deserves the focused attention of reproductive physicians.