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- 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.
- 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
- 16,078 View
- 226 Download
- 4 Web of Science
- 4 Crossref
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Abstract
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AbstractOBJECTIVES
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).METHODSAn 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.RESULTSThe 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.CONCLUSIONSThis 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. -
SummaryKorean 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
- Immunosuppressant use and adverse pregnancy outcomes in women with systemic lupus erythematosus: a retrospective cohort study in Korea
- Epidemiologic Study for the Association between Phenol Contaminated Drinking Water and Poor Pregnancy Outcomes in Taegu City.
- Jung Han Park, Ju Young Lee
- Korean J Epidemiol. 2000;22(1):20-31.
- 9,402 View
- 26 Download
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AbstractFrom 14 to 17 March 1991 the Nakdong River which is a major source of drinking water for Taegu was contaminated with phenol that was spilled out of a factory in Gumi industrial park. Many people who drank the contaminated water complained of various symptoms and were apprehensive of possible adverse effect to the fetus. This study was conducted to examine the effect of drinking water contaminated with phenol on pregnancy outcome in Taegu. All of livebirths and stillbriths delivered in the 5 General Hospitals in Taegu during 1 year from 1 April 1991 were included for this study. For this duration, total number of babies delivered in the 5 General Hospitals was 21,196. Among them, 77.7%(16,468) were delivered from women living in Taegu and it accounted for 47.5% of 34,688 livbirths registered in Taegu during the same period. The babies born to the women living in Taegu were divided into phenol-exposed and unexposed groups. Exposed group was the residents of the area where contaminated water was supplied and they accounted for 81.4% of the women included for this study. Unexposed group was the residents of the area where drinking water was not contaminated with phenol and they accounted for 18.6% of the study subjects. Data were abstracted from the hospital records. All the rates were adjusted for the maternal age and parity by direct method. The abortion rates for the exposed group was 1.7 per 1,000 abortions and livebirths and 1.6 for the unexposed group. The stillbirth rate for the exposed group was 10.5 per 1,000 livebirths and stillbirths 20 weeks of gestation and 9.5 for unexposed group. The early neonatal death rate(within the 1st week after birth) for the exposed group was 7.8 per 1,000 livebirths and 5.4 for the unexposed group. The perinatal death rate for the exposed group was higher as 14.1 per 1,000 livebirths and stillbirths 28 weeks of gestation than 10.8 for the unexposed group. The proportions of intrauterine growth retardation(IUGR) were 2.7% for the exposed group and 3.3% for the unexposed group. Congenital anomaly incidence rates per 1,000 livebirths was 7.4 for the exposed group and 8.4 for the unexposed group. The low birthweight incidence rate for the exposed group was 6.6% and 6.5% for the unexposed group. These differences between two groups were not statistically significant. The premature birth rate(< 37 completed gestational week) was 6.0% for the exposed group and 4.8% for the unexposed group and the difference was statistically significant(p<0.05). Monthly variation of these indices did not show any clue that suggested concurrent change with the phenol contamination of the drinking water. There were no sufficient evidence that could support the hypothesis of adverse effects of phenol contaminated water on pregnancy outcome, such as abortion, stillbirth, premature birth, IUGR, congenital anomalies and early neonatal death.
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