Abstract / Summary
Validated first-trimester combined screening for preeclampsia is not universally available, whereas dipstick urinalysis is inexpensive and routinely used. We evaluated whether first-trimester dipstick proteinuria is associated with subsequent preeclampsia after adjustment for prespecified maternal characteristics and assessed its pragmatic value as an adjunctive risk marker. This retrospective case-control study included 175 consecutive women who developed preeclampsia and 175 randomly selected normotensive, uncomplicated controls who received first-trimester antenatal care and delivered at the same tertiary institution between March 2022 and November 2024. Preeclampsia was defined according to the American College of Obstetricians and Gynecologists criteria. Women with chronic hypertension, known chronic kidney disease, diabetes mellitus, autoimmune disease, multiple gestation, or prior hypertensive disorder of pregnancy were excluded. Dipstick proteinuria at 11 + 0 to 13 + 6 weeks was categorized as negative/trace or positive (>= +1). Between-group comparisons used two-sided independent-samples t tests for continuous variables and chi-square or Fisher exact tests for categorical variables, as appropriate. The association with subsequent preeclampsia was evaluated using univariable and multivariable logistic regression, with maternal age, body mass index, and parity entered a priori as covariates. Exploratory receiver operating characteristic analysis and a secondary contemporaneous agreement analysis with 24-hour urine protein measurement after 20 weeks were also performed. First-trimester dipstick proteinuria >= +1 was more frequent among women who subsequently developed preeclampsia than among controls (74/175 [42.3%] vs. 28/175 [16.0%]; unadjusted odds ratio 3.85, 95% confidence interval 2.33–6.36; p < 0.001). The association remained significant after adjustment for maternal age, body mass index, and parity (adjusted odds ratio 3.49, 95% confidence interval 2.06–5.91; p < 0.001). At the prespecified >= +1 cutoff, specificity was 84.0% and sensitivity was 42.3%; discrimination was limited (AUC 0.63, 95% CI 0.59–0.68; p < 0.001). Women who developed preeclampsia delivered earlier and had higher frequencies of NICU admission, maternal ICU admission, transfusion, postpartum hemorrhage, and longer hospitalization than controls. In a secondary subgroup evaluated after 20 weeks for suspected hypertensive disease, contemporaneous dipstick testing showed high agreement with 24-hour protein quantification (Cohen kappa 0.85); this analysis was not interpreted as validation of first-trimester dipstick testing against later proteinuria. First-trimester dipstick proteinuria >= +1 remained associated with subsequent preeclampsia after adjustment for maternal age, body mass index, and parity. However, its low sensitivity and limited discrimination preclude use as a stand-alone screening test, and the case-control design does not permit estimation of absolute population risk or prevalence-dependent predictive values. These findings support a cautious role for dipstick proteinuria as an inexpensive adjunctive risk marker where validated combined first-trimester screening is unavailable, while prospective external validation remains necessary.