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Original Article
- 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
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AbstractOBJECTIVES
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.METHODSWe 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.RESULTSAlgorithm-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.CONCLUSIONSAlgorithm-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. -
SummaryKorean 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.
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