Skip Navigation
Skip to contents

Epidemiol Health : Epidemiology and Health

OPEN ACCESS
SEARCH
Search
Advanced Search
mobile menu button

Search

Page Path
HOME > Search
2 "Algorithms"
Filter
Filter
Article category
Keywords
More +
Publication year
Authors
More +
Funded articles
Original Articles
Evaluation of gestational age by pregnancy outcomes and distribution of pregnancy-related codes in Korean claims data
Woo-Jung Kim, Yunha Noh, Yongtai Cho, Eun-Young Choi, HyunJoo Lim, Hyesung Lee, Ju-Young Shin
Epidemiol Health. 2026;48:e2026007.   Published online February 4, 2026
DOI: https://doi.org/10.4178/epih.e2026007
  • 514 View
  • 30 Download
AbstractAbstract AbstractSummary PDF
Abstract
OBJECTIVES
This study aimed to evaluate a fixed-duration algorithm for gestational age (GA) estimation according to pregnancy outcomes and to describe the GA distribution of pregnancy-related codes in Korea.
METHODS
We included 351,055 pregnancy episodes (2019–2022) from linked data between the National Health Insurance Service and the Korea Immunization Registry Information System (KIRIS). GA from claims data was estimated by subtracting fixed durations from the delivery date (algorithm-based GA), and GA derived from KIRIS was defined as the gold standard. Accuracy was evaluated as the proportion of episodes in which the difference between the estimated GA and the reference standard fell within ±2 weeks. We described the distributions of the GA at which each prenatal test, pregnancy complication, and diagnostic code was recorded.
RESULTS
Algorithm-based GA estimation showed high accuracy for live births (92.2% within ±2 weeks) but markedly lower accuracy for non-live birth outcomes, including stillbirth (3.3%), termination (7.2%), spontaneous abortion (45.2%), and ectopic pregnancy (20.0%). In additional analyses aimed at identifying potential indicators for improving GA estimation, most events occurred within clinically expected timeframes, although some individual codes exhibited poor temporal alignment.
CONCLUSIONS
Algorithm-based GA estimation using claims data performed well for live births but demonstrated limited accuracy for non-live birth outcomes. Incorporating information from prenatal tests and pregnancy complications may enhance GA estimation.
Summary
Korean summary
본 연구는 국내 전국민 단위 청구자료와 예방접종 등록자료를 연계하여 고정 임신기간 기반 알고리즘의 재태연령 추정 정확도를 임신 결과별로 체계적으로 검증하였다. 출생아에서는 ±2주 기준 92.2%의 높은 정확도를 보였으나, 사산·인공임신중절·자연유산·자궁외임신 등 비출생 결과에서는 현저히 낮은 정확도를 보여 결과 유형에 따른 성능 이질성이 확인되었다. 산전검사 및 임신 합병증과 같은 시간 민감적 임상지표를 통합한 계층적 접근이 청구자료 기반 재태연령 추정의 타당도 향상에 기여할 수 있다.
Key Message
Using nationwide linked claims and immunization registry data in Korea, this study systematically validated the performance of a fixed-duration algorithm for gestational age estimation across pregnancy outcomes. While high accuracy was observed for live births (92.2% within ±2 weeks), substantially poorer performance was identified for non–live-birth outcomes, indicating marked outcome-specific heterogeneity. Integration of time-sensitive clinical indicators, including prenatal tests and pregnancy complications, may enhance the validity of gestational age estimation in administrative data research.
Identifying pregnancy episodes and estimating the last menstrual period using an administrative database in Korea: an application to patients with systemic lupus erythematosus
Yu-Seon Jung, Yeo-Jin Song, Jihyun Keum, Ju Won Lee, Eun Jin Jang, Soo-Kyung Cho, Yoon-Kyoung Sung, Sun-Young Jung
Epidemiol Health. 2024;46:e2024012.   Published online December 19, 2023
DOI: https://doi.org/10.4178/epih.e2024012
  • 15,969 View
  • 226 Download
  • 4 Web of Science
  • 4 Crossref
AbstractAbstract AbstractSummary PDFSupplementary Material
Abstract
OBJECTIVES
This study developed an algorithm for identifying pregnancy episodes and estimating the last menstrual period (LMP) in an administrative claims database and applied it to investigate the use of pregnancy-incompatible immunosuppressants among pregnant women with systemic lupus erythematosus (SLE).
METHODS
An algorithm was developed and applied to a nationwide claims database in Korea. Pregnancy episodes were identified using a hierarchy of pregnancy outcomes and clinically plausible periods for subsequent episodes. The LMP was estimated using preterm delivery, sonography, and abortion procedure codes. Otherwise, outcome-specific estimates were applied, assigning a fixed gestational age to the corresponding pregnancy outcome. The algorithm was used to examine the prevalence of pregnancies and utilization of pregnancy-incompatible immunosuppressants (cyclophosphamide [CYC]/mycophenolate mofetil [MMF]/methotrexate [MTX]) and non-steroidal anti-inflammatory drugs (NSAIDs) during pregnancy in SLE patients.
RESULTS
The pregnancy outcomes identified in SLE patients included live births (67%), stillbirths (2%), and abortions (31%). The LMP was mostly estimated with outcome-specific estimates for full-term births (92.3%) and using sonography procedure codes (54.7%) and preterm delivery diagnosis codes (37.9%) for preterm births. The use of CYC/MMF/MTX decreased from 7.6% during preconception to 0.2% at the end of pregnancy. CYC/MMF/MTX use was observed in 3.6% of women within 3 months preconception and 2.5% during 0-7 weeks of pregnancy.
CONCLUSIONS
This study presents the first pregnancy algorithm using a Korean administrative claims database. Although further validation is necessary, this study provides a foundation for evaluating the safety of medications during pregnancy using secondary databases in Korea, especially for rare diseases.
Summary
Korean summary
임산부의 약물 사용 안전성에 대한 근거 제공을 위해 실제 인구집단에서의 임신 중 약물 치료 안전성을 평가하는 청구자료 기반 연구가 중요하다. 본 연구에서는 국내 청구자료에 적용할 수 있는 임신 정의 및 임신 결과 조작적 정의 알고리즘을 개발하였다. 본 알고리즘은 임신 결과 간의 우선순위를 고려한 계층 구조를 활용하며, 조기 분만 및 초음파 검사 코드 등을 통해 최종 월경 기간을 추정하였다. 또한 알고리즘을 전신홍반루푸스 환자에 적용하여 유산, 사산 등의 유병률을 산출하고 임신 중 잠재적으로 부적절한 면역억제제 사용을 파악하여 국내 청구자료의 특성을 고려한 임신 중 약물 사용 연구의 기반을 마련하였다.
Key Message
Limited safety data for pregnant women prompted recent studies on medication during pregnancy using real-world databases. This study developed a tailored algorithm for Korean healthcare claims database, employing a hierarchy of pregnancy outcomes and incorporating pre-term delivery and sonography codes for last menstrual period estimation. Applied to systemic lupus erythematosus (SLE) patients, this study presented the prevalence and drug utilization pattern of pregnancy-incompatible immunosuppressants from preconception to pregnancy end, laying a foundation for further claims database studies on medication pregnancy safety.

Citations

Citations to this article as recorded by  
  • Immunosuppressant use and adverse pregnancy outcomes in women with systemic lupus erythematosus: a retrospective cohort study in Korea
    Yu-Seon Jung, Yeo-Jin Song, Eun Jin Jang, Soo-Kyung Cho, Yoon-Kyoung Sung, Sun-Young Jung
    Rheumatology.2026;[Epub]     CrossRef
  • Utilisation patterns of immunomodulators and pregnancy outcomes in systemic lupus erythematosus: Insights from Korean national data
    Yu-Seon Jung, Yeo-Jin Song, Hyeon Ji Lee, Eunji Kim, Soo-Kyung Cho, Yoon-Kyoung Sung, Sun-Young Jung
    Lupus.2025; 34(2): 140.     CrossRef
  • Narrative Review of National Health Insurance Claims Data for Gestational Age Calculation and Vaccine Safety Evaluation in Pregnancy
    Taemi Kim, Seung-Ah Choe
    Health Insurance Review & Assessment Service Research.2025; 5(2): 98.     CrossRef
  • Neurodevelopmental delays in children born after medically assisted reproduction: a national population cohort study
    Seung-Ah Choe, Eunseon Gwak, Juyoung Lee, Jung Hye Byeon, Ju-Young Shin, Seungbong Han, Jee Hyun Kim
    Journal of Neurodevelopmental Disorders.2025;[Epub]     CrossRef
Epidemiol Health : Epidemiology and Health
© Korean Society of Epidemiology.
TOP