Risk Factors and Outcomes of Recurrent Pregnancy Loss in Japan

Keiko Morita, Yosuke Ono, Toshiyuki Takeshita, Toshitaka Sugi, Tomoyuki Fujii, Hideto Yamada, Mikiya Nakatsuka, Atsushi Fukui, Shigeru Saito

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Aim: To clarify the risk factors and pregnancy outcomes for each risk factor of recurrent pregnancy loss (RPL) in Japan. Methods: Using a prospective RPL database collected from 16 facilities in Japan, the prevalence of risk factors for RPL, their treatments and pregnancy outcomes were examined. Results: Of 6663 patients registered in our database, 5708 patients had RPL. All examinations for risk factors were performed for 1340 patients (23.5%). The prevalences of positive antiphospholipid antibodies (aPL), malformation of the uterus, thyroid dysfunction, parental karyotype abnormality, factor XII deficiency, protein S deficiency and unknown risk factors were 8.7%, 7.9%, 9.5%, 3.7%, 7.6%, 4.3% and 65.1%, respectively. Although factor XII deficiency and protein S deficiency are not recognized as risk factors for RPL in general, low-dose aspirin (LDA) or unfractionated heparin + LDA therapy improved live birth rates. In transiently aPL-positive patients, the live birth rate with LDA therapy was similar to that with heparin + LDA. For unknown risk factors of RPL, the live birth rate in normal fetal karyotype in the none treatment group was similar to that in all other treatments group (81.3% vs 86.0%). Of 5708 RPL patients, pregnancy outcomes were known for 2261 patients and 1697 patients (75.1%) had at least one live birth. Conclusion: The risk factors and pregnancy outcomes for each risk factor of RPL are useful for clinicians and patients. Factor XII deficiency and protein S deficiency may be risk factors of RPL.

Original languageEnglish
Pages (from-to)1997-2006
Number of pages10
JournalJournal of Obstetrics and Gynaecology Research
Issue number10
Publication statusPublished - Oct 1 2019


  • factor XII deficiency
  • pregnancy outcomes
  • protein S deficiency
  • recurrent pregnancy loss
  • risk factors

ASJC Scopus subject areas

  • Obstetrics and Gynaecology


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