Open AccessIdentifying a possible factor for the increased newborn size in singleton pregnancies after assisted reproductive technology using cryopreserved embryos, in comparison with fresh embryos
Author(s) -
Ishii Rena,
Shoda Akiko,
Kubo Michiyo,
Okazaki Satiko,
Suzuki Minori,
Okawa Riho,
Enomoto Megumi,
Shitanaka Manami,
Fujita Yoko,
Nakao Kazuki,
Shimada Nobutaka,
Horikawa Michiharu,
Negishi Hiroaki,
Taketani Yuji
Publication year - 2018
Publication title -
reproductive medicine and biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.005
H-Index - 22
eISSN - 1447-0578
pISSN - 1445-5781
DOI - 10.1002/rmb2.12206
Subject(s) - endometrium , embryo transfer , embryo , gynecology , assisted reproductive technology , medicine , cryopreservation , pregnancy , andrology , obstetrics , biology , infertility , genetics , microbiology and biotechnology
Purpose To determine whether the cycle regimens that are used for endometrial preparation are associated with the birthweight ( BW ) after assisted reproductive technology ( ART ) using frozen‐thawed embryo transfer ( FET ). Methods The BW of singletons who were born by ART using FET was compared retrospectively, according to whether a FET was conducted in a hormone replacement therapy cycle ( HRT , n = 403) or an ovulatory cycle ( OVL , n = 117). The BW after timed intercourse ( NAT , n = 162) also was investigated. Results There were no significant differences in the age of the mothers, percentage of primiparas, gestational periods, Body Mass Index, and sex ratio between the HRT and OVL cycles. The average BW from HRT was significantly greater than that of OVL . The BW from HRT was also greater, compared with NAT , while statistical significance was not achieved between OVL and NAT . The putative factors affecting the BW , such as ovarian stimulation protocols, endometrial thickness, and the stage and quality of embryos, could not explain the difference in the BW between the HRT and OVL cycles. Conclusion An increased BW from ART using FET seems to be ascribable to conditions of the endometrium, but not cryopreservation procedures per se, which might provide a mechanistic framework for understanding heavier neonates who are born by FET .