Metabolic and Hypertensive Complications of Pregnancy in Women with Nephrolithiasis

Background and objectives Kidney stones are associated with future development of hypertension, diabetes, and the metabolic syndrome. Our objective was to assess whether stone formation before pregnancy was associated with metabolic and hypertensive complications in pregnancy. We hypothesized that stone formation is a marker of metabolic disease and would be associated with higher risk for maternal complications in pregnancy. Design, setting, participants, & measurements We conducted a retrospective cohort study of women who delivered infants at the Massachusetts General Hospital from 2006 to 2015. Women with abdominal imaging (computed tomography or ultrasound) before pregnancy were included in the analysis. Pregnancy outcomes in women with documented kidney stones on imaging (stone formers, n=166) were compared with those of women without stones on imaging (controls, n=1264). Women with preexisting CKD, hypertension, and diabetes were excluded. Results Gestational diabetes and preeclampsia were more common in stone formers than nonstone formers (18% versus 6%, respectively; P<0.001 and 16% versus 8%, respectively; P=0.002). After multivariable adjustment, previous nephrolithiasis was associated with higher risks of gestational diabetes (adjusted odds ratio, 3.1; 95% confidence interval, 1.8 to 5.3) and preeclampsia (adjusted odds ratio, 2.2; 95% confidence interval, 1.3 to 3.6). Infants of stone formers were born earlier (38.72.0 versus 39.2 +/- 1.7 weeks, respectively; P=0.01); however, rates of small for gestational age offspring and neonatal intensive care admission were similar between groups (8% versus 7%, respectively; P=0.33 and 10% versus 6%, respectively; P=0.08). First trimester body mass index significantly influenced the association between stone disease and hypertensive complications of pregnancy: in a multivariable linear regression model, stone formation acted as an effect modifier of the relationship between maximum systolic BP in the third trimester and body mass index (P interaction <0.001). Conclusions In women without preexisting diabetes, hypertension, and CKD, a history of nephrolithiasis was associated with gestational diabetes and hypertensive disorders of pregnancy, especially in women with high first trimester body mass index.