Background: Hypertensive disorders of pregnancy are important causes of maternal and perinatal morbidity and mortality. Early identification of women at risk of pregnancy-induced hypertension (PIH) may facilitate closer surveillance and timely intervention. Reduced urinary calcium excretion and a low urinary calcium-creatinine ratio (UCa/Cr) have been proposed as potential early markers of preeclampsia.

Aim: To evaluate the urinary calcium-creatinine ratio in a spot urine sample obtained before 20 weeks of gestation and assess its utility in predicting pregnancy-induced hypertension.

Methods: This prospective observational study was conducted in the Department of Obstetrics and Gynecology, Rajkiya Mahila Chikitsalaya, JLN Medical College, Ajmer, from June 2023 to May 2024. A total of 270 normotensive pregnant women with singleton pregnancies and gestational age <20 weeks were enrolled. Women with hypertension, proteinuria, previous PIH, chronic hypertension, multiple pregnancy, diabetes mellitus, renal, vascular or immunological disease were excluded. A spot urine sample was analyzed for calcium and creatinine, and the urinary calcium-creatinine ratio was calculated. Participants were followed throughout pregnancy for development of PIH.

Results: Of 270 women, 60 (22.22%) developed PIH and 210 (77.78%) remained normotensive. The most common age group was 26–30 years in both groups. Age, parity, socioeconomic status, gestational age at enrollment and family history of hypertension were not significantly associated with PIH. Cesarean delivery was more frequent among women with PIH (35.0% vs. 20.95%; p=0.024). BMI was significantly associated with PIH (p<0.0001), with overweight women constituting 55.0% of the PIH group. Mean urinary calcium-creatinine ratio was significantly lower among women who developed PIH (0.04±0.02) than among normotensive women (0.18±0.06; p<0.0001). A UCa/Cr ≤0.04 was present in 91.67% of PIH women compared with 1.90% of normotensive women (p<0.0001). The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were 91.67%, 98.10%, 93.22%, 97.63% and 96.67%, respectively.

Conclusion: A low urinary calcium-creatinine ratio, particularly a value ≤0.04, was strongly associated with subsequent pregnancy-induced hypertension. Spot urinary UCa/Cr is a simple, non-invasive and inexpensive biomarker that may have potential utility in early risk stratification of pregnant women.