Although urolithiasis is relatively common in the general population, there is limited information on this condition available in the pregnant population. The objectives of this study are to identify the incidence of urolithiasis in pregnancy, as well as to compare maternal and fetal outcomes associated with urolithiasis in pregnancy.

Using the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample database from the United States, a population-based retrospective cohort study consisting of pregnant women who delivered between 1999 and 2015 was conducted. ICD-9-CM code 592.X was used to identify pregnant women with urolithiasis within the cohort, with pregnant women without urolithiasis forming the comparison group. Unconditional logistic regression models were used to estimate the associations between urolithiasis in pregnancy and maternal and neonatal outcomes, while adjusting for baseline maternal characteristics.

A cohort of 13,792,544 pregnant women was identified, of which 11,528 had a urolithiasis-related admission during pregnancy, for an overall incidence of 8.3 per 10,000 pregnancies. Women with urolithiasis had a greater risk of developing preeclampsia/eclampsia, OR 1.35(95% CI 1.24-1.47), gestational diabetes, 1.29(1.20-1.30), abruptio placenta, 1.41(1.22-1.64), placenta previa, 1.55(1.27-1.90), pyelonephritis, 88.87(81.69-96.69), venous thromboembolism, 1.65(1.23-2.22), and more likely to deliver by cesarean, 1.20(1.15-1.25). As well, maternal death was more common among these women, 2.85(1.07-7.60). Congenital anomalies, 2.84(2.43-3.31) and prematurity, 1.92(1.82-2.03) were more commonly found among babies born to women with urolithiasis.

Although the mechanism is unclear, women with urolithiasis in pregnancy have an increased risk of adverse pregnancy and newborn outcomes.