Proteinuria in Pregnancy: A Key Factor in Chronic Hypertension Management

Purpose: This study aims to determine whether new-onset proteinuria is a clinically significant predictor of adverse maternal and fetal outcomes in pregnancies complicated by chronic hypertension. Methods: This retrospective cohort study was conducted at a single center that included five birthing hospitals in the Metropolitan Detroit area, conducted between 2015 and 2022. The primary outcome measure was the development of superimposed preeclampsia with severe features. Secondary maternal outcomes included the development of preeclampsia without severe features, preterm delivery, and gestational age at delivery. Secondary fetal outcomes included fetal growth restriction and admission to the neonatal intensive care unit. Covariates analyzed included age, race, obesity, and presence of pregestational or gestational diabetes. All patients were treated with antihypertensive agents, specifically nifedipine or labetalol. Exclusion criteria included absence of baseline proteinuria assessment, absence of hypertension, multifetal gestation, or missing covariate data. Only the first pregnancy was included for patients with multiple pregnancies within the cohort. Descriptive statistics were reported as mean ± standard deviation for continuous variables and as frequencies with percentages for categorical variables. The normality of continuous variables was assessed using the Shapiro-Wilk test. Group comparisons based on new-onset proteinuria were conducted using a two-sample t-test for continuous variables and a Chi-square test for categorical variables. If the assumptions were not met, the Wilcoxon rank-sum test or Fisher’s exact test was applied. Poisson regression with robust error variances was used to calculate risk ratios (RR) and 95% confidence intervals (CI) for binary outcomes, while linear regression was used for continuous outcomes. Both unadjusted and adjusted models were analyzed, accounting for potential confounders. Statistical significance was defined as p < 0.05. Results: Among the 3815 patients with chronic hypertension included in the study, 890 exhibited a normal baseline urine protein-to-creatinine ratio. During pregnancy, 248 (27.9%) developed new-onset proteinuria, while 642 remained without proteinuria. The incidence of new-onset proteinuria was significantly higher among Black patients. Those who developed new-onset proteinuria were more likely to experience adverse maternal and neonatal outcomes, including a significantly higher likelihood of developing preeclampsia with severe features (11.3% vs. 4.0%, p