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18 March 2019

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Int J Med Sci 2015; 12(1):57-62. doi:10.7150/ijms.10352

Research Paper

The Effect of Single Embryo Transfer on Perinatal Outcomes in Japan

Masako Hayashi1✉, Shoji Satoh2, Yoshio Matsuda3, Akihito Nakai1

1. Department of Obstetrics and Gynecology, Nippon Medical School, Tokyo, Japan;
2. Maternal and Perinatal Care Center, Oita Prefectural Hospital, Oita, Japan;
3. Department of Obstetrics and Gynecology, International University of Health and Welfare, Tochigi, Japan.


Objective: In 2007 and 2008, the Japan Society for Reproductive Medicine and the Japan Society of Obstetrics and Gynecology issued a recommendation for single embryo transfer (SET). Thereafter, SET was implemented in 73% of in vitro fertilization (IVF) cases in Japan. The purpose of this study was to evaluate the effects of compliance with the SET recommendation on perinatal outcomes.

Methods: An electronic audit of the perinatal database of the Japanese Society of Obstetrics and Gynecology was conducted from 2001 through 2010. The database comprised data of 610,726 women. Totally, 20,923 women conceived through IVF. To compare perinatal outcomes, these women were categorized into two study groups depending on whether they conceived before (2004-2005, n = 3,865) or after (2009-2010, n = 6,842) the SET recommendation statement was issued.

Results: The proportion of women who conceived through IVF increased from 1.3% in 2001 to 4.8% in 2010. Compliance with the SET recommendation led to a decrease in the incidence of twin pregnancies (33.9% versus 13%, p < 0.01), incidence of preterm delivery (odds ratio [OR]: 0.54, 95% confidence interval [CI]: 0.50-0.59), low birth weight (OR: 0.42, 95% CI: 0.39-0.45), and neonatal intensive care unit admission (OR 0.70, 95% CI 0.65-0.76), but an increase in the incidence of monochorionic twins (1.6% versus 2.5%, p < 0.01).

Conclusion: Compliance with the SET recommendation improved perinatal outcomes by reducing the incidence of twin pregnancies.

Keywords: in vitro fertilization, twin pregnancy, monochorionic twin, obstetric outcome, perinatal outcome.

This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY-NC) License. See for full terms and conditions.
How to cite this article:
Hayashi M, Satoh S, Matsuda Y, Nakai A. The Effect of Single Embryo Transfer on Perinatal Outcomes in Japan. Int J Med Sci 2015; 12(1):57-62. doi:10.7150/ijms.10352. Available from