Analysis of 122 triplet and 1 quadruplet pregnancies after single embryo transfer in Japan

Abstract Research question To estimate the prevalence of triplet and quadruplet pregnancies after single embryo transfer (SET) in Japan. Design We conducted a retrospective observational study on 274,605 pregnancies after 937,848 SET cycles in registered assisted reproductive technology (ART) data from the Japan Society of Obstetrics and Gynaecology between 2007 and 2014. We also conducted a questionnaire survey of hospitals that provided ART, and we also collected and analysed data on pregnancies with embryo division into three or more after SET. Results According to the Japanese ART national registry database, SET resulted in 109 triplet pregnancies (0.04% of pregnancies), whereas the questionnaire survey revealed 33 triplet and 1 quadruplet pregnancies. After exclusion of 20 duplicated cases, a total of 122 triplet and 1 quadruplet pregnancies, including 46 monochorionic (1 gestational sac [GS], 37.4%), 18 dichorionic (2 GSs, 14.6%) and 59 trichorionic pregnancies (3 GSs, 48.0%). Compared with singleton pregnancies, patients with monozygotic triplet or quadruplet pregnancies were less frequently diagnosed with unexplained infertility (P = 0.004), received more gonadotropin injections (P = 0.021) and underwent more blastocyst cultures and assisted hatching (AH) (P = 0.002 and Conclusions The Japanese ART national registry data revealed 122 triplet and 1 quadruplet pregnancies, which were conceived after embryo manipulations using blastocyst transfer and AH as potential risk factors for zygotic splitting.