Shiru Xu1,2, Qizhen Zheng2, Meilan Mo2, Feng Xiong2, Xiuyu Hu2, Yong Zeng3. 1. Center for Reproductive Medicine, Shandong University, National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, 250100, Shandong, People's Republic of China. 2. Shenzhen Key Laboratory of Reproductive Immunology for Peri-Implantation, Shenzhen Zhongshan Institute for Reproduction and Genetics, Shenzhen Zhongshan Urology Hospital, Shenzhen, Guangdong, 518045, People's Republic of China. 3. Shenzhen Key Laboratory of Reproductive Immunology for Peri-Implantation, Shenzhen Zhongshan Institute for Reproduction and Genetics, Shenzhen Zhongshan Urology Hospital, Shenzhen, Guangdong, 518045, People's Republic of China. zengyong1966@gmail.com.
Abstract
BACKGROUND: The aim of this study was to explore specific factors that predispose to monozygotic twinning (MZT) at the blastocyst stage. METHODS: This was a retrospective observational study of a cohort of 2863 pregnancies after single blastocyst transfer (SBT) between January 2011 and June 2019 in our hospital. MZT pregnancy was identified as the number of fetuses exceeded the number of gestational sacs (GSs) by transvaginal ultrasound at 6-7 gestational weeks. The incidences of MZT regarding the maternal age at oocyte retrieval, paternal age, ovarian stimulation protocol, fertilization method, endometrium preparation protocol, vitrified day, and the Gardner grading of the blastocyst were calculated. The serum estrogen (E2), progesterone (P) levels, endometrium thickness and serum hCG levels on day 11 after embryo transfer (ET) were compared between the MZT and singleton pregnancies. Statistical analyses were used appropriately. RESULTS: Fifty-one MZT pregnancies (1.78%) were identified. The only significant differences observed between MZT and singleton pregnancies were the proportion of TE grade (P = 0.022) and the hCG levels on day 11 after ET (P = 0.003). Multivariate logistic regression revealed that trophectoderm (TE) grade was an independent factor affecting MZT, the adjusted odds ratios (aORs) of grade A and B TE were 5.46 [95% confidential interval (CI) 1.48-20.16, P = 0.011) and 3.96 (95% CI 1.17-13.40, P = 0.027) compared to grade C respectively. There were no significant associations between the parental age, fertilization method, ovarian stimulation protocol, endometrium preparation protocol, vitrified day, expansion stage, inner cell mass (ICM) grade and MZT. CONCLUSIONS: TE grade is associated with MZT at the blastocyst stage, potentially mediated via increased secretion of hCG from more well developed TE. Increased hCG secretion in turn may prolong the implantation window to support the embryo splitting.
BACKGROUND: The aim of this study was to explore specific factors that predispose to monozygotic twinning (MZT) at the blastocyst stage. METHODS: This was a retrospective observational study of a cohort of 2863 pregnancies after single blastocyst transfer (SBT) between January 2011 and June 2019 in our hospital. MZT pregnancy was identified as the number of fetuses exceeded the number of gestational sacs (GSs) by transvaginal ultrasound at 6-7 gestational weeks. The incidences of MZT regarding the maternal age at oocyte retrieval, paternal age, ovarian stimulation protocol, fertilization method, endometrium preparation protocol, vitrified day, and the Gardner grading of the blastocyst were calculated. The serum estrogen (E2), progesterone (P) levels, endometrium thickness and serum hCG levels on day 11 after embryo transfer (ET) were compared between the MZT and singleton pregnancies. Statistical analyses were used appropriately. RESULTS: Fifty-one MZT pregnancies (1.78%) were identified. The only significant differences observed between MZT and singleton pregnancies were the proportion of TE grade (P = 0.022) and the hCG levels on day 11 after ET (P = 0.003). Multivariate logistic regression revealed that trophectoderm (TE) grade was an independent factor affecting MZT, the adjusted odds ratios (aORs) of grade A and B TE were 5.46 [95% confidential interval (CI) 1.48-20.16, P = 0.011) and 3.96 (95% CI 1.17-13.40, P = 0.027) compared to grade C respectively. There were no significant associations between the parental age, fertilization method, ovarian stimulation protocol, endometrium preparation protocol, vitrified day, expansion stage, inner cell mass (ICM) grade and MZT. CONCLUSIONS: TE grade is associated with MZT at the blastocyst stage, potentially mediated via increased secretion of hCG from more well developed TE. Increased hCG secretion in turn may prolong the implantation window to support the embryo splitting.
Authors: Caroline Brogliato; Janaína Romanini; Caroline Z Berton; Claudia H Suganuma; Laura T Vellez; Ivan H Yoshida; Caio P Barbosa Journal: JBRA Assist Reprod Date: 2020-05-01