Predictors of Hypertensive Disorders of Pregnancy in Japan: A Population-Based Retrospective Cohort Study Using the Shizuoka Kokuho Database.

AIM: To identify the predictors of the onset of hypertensive disorders of pregnancy (HDP) in pregnant women in Japan.

METHODS

This population-based, retrospective cohort study was conducted in Shizuoka Prefecture, Japan, using data from the Shizuoka Kokuho Database from 2012 to 2020. A 1-year baseline period and a 280-day follow-up period were defined for each participant. The outcome was the occurrence of HDP, identified using the International Classification of Diseases, 10th Revision codes. Candidate predictors included maternal age, residential area, and baseline comorbidities. Associations were assessed using multivariable logistic regression and conditional inference tree analysis.

RESULTS

A total of 6362 pregnant women were included. Among them, 222 (3.5%) were diagnosed with HDP. Multivariable logistic regression identified advanced maternal age (odds ratio [OR] 1.05, 95% confidence interval [CI] 1.02-1.07), diabetes mellitus (OR 3.21, 95% CI 1.22-8.47), preexisting hypertension (OR 2.38, 95% CI 1.04-5.46), and systemic lupus erythematosus (OR 5.90, 95% CI 1.41-24.65) as predictors of HDP onset. In sensitivity analyses excluding women with preexisting hypertension, maternal age, diabetes mellitus, systemic lupus erythematosus, and obesity remained associated with HDP onset. Conditional inference tree analysis identified maternal age > 34 years as the primary splitting variable, followed by hyperlipidemia, hypertension, and liver disease. Among women aged > 34 years without hyperlipidemia or hypertension, polycystic ovary syndrome was associated with increased risk of HDP.

CONCLUSIONS

We delineated a multifactorial risk profile for HDP. These findings indicate that routinely collected claims data may facilitate earlier risk stratification and support more individualized prenatal care.