Maternal and fetal outcomes of pregnancies complicated with urolithiasis: a retrospective cohort study

Abstract

Objectives Although urolithiasis is common in the general population, information on its impact on pregnancy is scarce. The objectives of this study are to identify the incidence of urolithiasis in pregnancy, as well as to compare maternal and fetal outcomes of kidney stones with pregnancies not affected by kidney stones. Methods A population-based cohort study consisting of pregnant women was carried out using the United States’ Healthcare Cost and Utilization Project-Nationwide Inpatient Sample from 1999-2015. Exposure was classified by the presence or absence of the ICD-9-CM code 592.X which identified those women diagnosed in admission with calculus of the kidney and/or ureter. Logistic regression was used to evaluate the effect of urolithiasis on maternal and newborn outcomes. Results A cohort of 13,792,544 pregnant patients was identified, of which 11,528 had urolithiasis during pregnancy, resulting in an overall incidence of urolithiasis in pregnancy was 8.3/10,000 pregnancies. Women with urolithiasis were more likely to have 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), and to deliver by cesarean (1.20, 1.15-1.25). Postpartum pyelonephritis (88.87, 81.69-96.69) and maternal death (2.85, 1.07-7.60) were more common. Pregnancies complicated by urolithiasis had greater risk of congenital anomalies (2.84, 2.43-3.31) and preterm birth (1.92, 1.82-2.03), with lower risk of intrauterine fetal death (0.60, 0.45-0.81). Conclusions After observing higher rates of obstetrical complications and poor neonatal outcomes among women with kidney stones, we hypothesize that these women experience a more challenging pregnancy compared with women whom did not have renal calculi during pregnancy.