Cryopreserved embryo replacement is associated with higher birthweight compared with fresh embryo: multicentric sibling embryo cohort study

• Published in: Scientific reports Vol. 9; no. 1; pp. 13402 - 7
• Main Authors: Anav, Margaux, Phillips, Simon, Ferrieres-Hoa, Alice, Gala, Anna, Fournier, Alice, Vincens, Claire, Vintejoux, Emmanuelle, Maris, Elsa, Grysole, Camille, Bissonnette, François, Brouillet, Sophie, Kadoch, Isaac Jacques, Hamamah, Samir
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.09.2019; Nature Publishing Group
• Subjects: 631/136; 631/1647; Adult; Birth Weight; Cohort analysis; Cryopreservation; Cryopreservation - methods; Development Biology; Embryo Culture Techniques - methods; Embryo transfer; Embryo Transfer - methods; Embryo, Mammalian - cytology; Embryos; Female; Fertilization; Fertilization in Vitro - methods; Freezing; Gestational Age; Gynecology and obstetrics; Human health and pathology; Humanities and Social Sciences; Humans; In vitro fertilization; Life Sciences; Male; multidisciplinary; Oocytes - cytology; Pregnancy; Retrospective Studies; Science; Science (multidisciplinary); Siblings; Supernumerary; Thawing; frozen embryo transfer (FET); Birth weight (BW); Cryopreservation
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-49708-7

Birth weight (BW) is higher after frozen embryo transfer (FET) than after fresh embryo replacement. No study has compared the BW of siblings conceived using the same oocyte/embryo cohort. The aim of this study was to determine whether the freezing-thawing procedure is involved in such difference. Multicenter study at Montpellier University Hospital, Clinique Ovo, Canada and Grenoble-Alpes University Hospital. The first cohort (Fresh/FET) included in vitro fertilization (IVF) cycles where the older was born after fresh embryo transfer (n = 158) and the younger after transfer of frozen supernumerary embryos (n = 158). The second cohort (FET/FET) included IVF cycles where older and younger were born after FET of embryos from the same cohort. The mean adjusted BW of the FET group was higher than that of the fresh group (3508.9 ± 452.4 g vs 3237.7 ± 463.3 g; p < 0.01). In the FET/FET cohort, the mean adjusted BW was higher for the younger by 93.1 g but this difference is not significant (3430.2 ± 347.6 g vs 3337.1 ± 391.9 g; p = 0.3789). Our results strongly suggest that cryopreservation is directly involved in the BW variation. Comparing BW difference between Fresh/FET cohort and FET/FET one, it suggests that parity is not the only responsible, increasing the role of cryopreservation step in BW variation.