Salivary uric acid remote serial self‐testing for prediction of adverse pregnancy outcomes of uteroplacental dysfunction

Introduction: Hypertensive disorders of pregnancy (HDP) and fetal growth restriction(FGR) are major manifestations of uteroplacental dysfunction and remain leading causes of maternal and perinatal morbidity. Current strategies for risk assessment rely on hospital-based screening or diagnostic triage and do not provide continuous, personalized monitoring throughout pregnancy. Uric acid is closely linked to placental dysfunction, and salivary uric acid (SUA) reflects circulating concentrations, enabling non invasive remote measurement. This study evaluated whether serial, smartphone-enabled self-testing of SUA could predict adverse pregnancy outcomes related to uteroplacental dysfunction.

Material and Methods: In this prospective observational cohort study, pregnant women were recruited at 20–22 weeks' gestation at a tertiary hospital. Participants performed weekly salivary self-testing using colorimetric uric acid strips until delivery, with results captured via a smartphone application. Images were analyzed using RGB color metrics. Primary outcomes were HDP and/or FGR, defined using ISSHP and FIGO criteria, respectively. Logistic regression models incorporated 4 weeks of lagged RGB-derived SUA metrics together with maternal characteristics. Model performance was assessed using area under the receiver operating characteristic curve (AUC) and calibration metrics, stratified by gestational age at outcome.

Results: Of 495 recruited participants, 318 women with complete longitudinal data were included in the final analysis; 36 (11.3%) developed HDP and/or FGR. A multivariable model combining maternal risk factors with 4 weeks of serial SUA measurements demonstrated good predictive performance. Discrimination was highest for preterm outcomes, with an AUC of 0.814 for prediction within 1 week at<37 weeks' gestation and prediction remained acceptable at term (AUC 0.732).

Conclusions: Remote serial self-testing of salivary uric acid is feasible and shows good predictive ability for adverse pregnancy outcomes related to uteroplacental dysfunction. This non invasive approach has potential to complement existing screening and surveillance strategies by enabling continuous, personalized risk assessment throughout pregnancy. Prospective validation in larger and more diverse populations is warranted.