Childbirth in young Korean women with previously treated breast cancer: The SMARTSHIP study

Hak Min Lee, Bo Wook Kim, Seho Park, Sungmin Park, Jeon Eon Lee, Young Jin Choi, Sung Yong Kim, Sang Uk Woo, Hyun Jo Youn, Ilkyun Lee

    Research output: Contribution to journalArticlepeer-review

    8 Citations (Scopus)


    Purpose: Alongside the modern trend of delaying childbirth, the high incidence of breast cancer among young women is causing significant pregnancy-related problems in Korea. We estimated the incidence of childbirth for young Korean breast cancer survivors compared with women who did not have breast cancer using a nationally representative dataset. Methods: Using a database from the National Health Insurance Service in South Korea, we analyzed 109,680 women who were between 20 and 40 years old between 2007 and 2013. They were prospectively followed, and childbirth events were recorded until December 31, 2015. We compared childbirth rates and characteristics between the breast cancer survivors and the noncancer controls. Results: Compared to 10,164 childbirths among 91,400 women without breast cancer (incidence rate: 22.3/1000), 855 childbirths occurred among 18,280 breast cancer survivors (incidence rate: 9.4/1000); the adjusted hazard ratio (HR) for childbirth was 0.41 (95% CI 0.38–0.44). Chemotherapy, endocrine therapy, and target therapy were associated with the decreasing childbirths among survivors, with corresponding adjusted HRs of 0.61 (0.53–0.70), 0.44 (0.38–0.51), and 0.62 (0.45–0.86), respectively. Breast cancer survivors had a lower probability of full-term delivery and a higher frequency of preterm labor than controls, with corresponding adjusted ORs of 0.78 (0.68–0.90) and 1.33 (1.06–1.65), respectively. Conclusions: We showed that a history of breast cancer has a negative effect on childbirth among young premenopausal women in Korea. Breast cancer survivors should be aware that they have a higher risk for preterm labor and are less likely to have a full-term delivery than women without a history of breast cancer.

    Original languageEnglish
    Pages (from-to)419-427
    Number of pages9
    JournalBreast Cancer Research and Treatment
    Issue number2
    Publication statusPublished - 2019 Jul 30

    Bibliographical note

    Funding Information:
    Acknowledgements This work was supported by the Korean Breast Cancer Society and the Study of Multi-disciplinARy Teamwork for breast cancer survivorSHIP (SMARTSHIP). This study enrolled patients from the National Health Information Database (NHIS-2017-4-011), which was provided and is maintained by the National Health Insurance Service (NHIS). The authors would like to thank the National Health Insurance Service for cooperation.

    Publisher Copyright:
    © 2019, Springer Science+Business Media, LLC, part of Springer Nature.


    • Breast cancer survivor
    • Childbirth
    • Incidence rate

    ASJC Scopus subject areas

    • Oncology
    • Cancer Research


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