Risk of Postpartum Urinary Stone Disease in Women with History of Urinary Stone Disease during Pregnancy

Objective: To determine the risk of postpartum urinary stone disease in women with a history of stone disease during pregnancy. Methods: Using the Optum® de-identified Clinformatics® Datamart we identified pregnant women with urinary stone disease in the United States between January 2003 to December 2017 by standardized International Classification of Diseases Ninth and Tenth Editions (ICD-9 and ICD-10), and Current Procedural Terminology code criteria. We limited the cohort to include women without evidence of urinary stone disease before pregnancy. We abstracted patient demographic characteristics, clinical risk factors for stone disease, and data for urinary stone disease encounters and related procedures after pregnancy. Encounters occurring within 1 year of pregnancy were excluded. Cox proportional hazard models were used to analyze for significance. Results: We identified a total of 1,395,783 pregnant women with a median postpartum follow-up of 4.0 years, including 5971 (0.4%) women with a urinary stone during pregnancy. Of these, 736 (12.3%) had an additional urinary stone diagnosis claim after pregnancy, compared with 13,275 (0.95%) women without a history of stone disease during pregnancy (p < 0.0001). In multivariable proportional hazards models urinary stone disease during pregnancy (hazards ratio 12.8, 95% confidence interval [11.8-13.8]) was independently associated with a higher hazard of urinary stone disease after pregnancy. Conclusion: Women with urinary stone disease during pregnancy were more likely to present with recurrent urinary stone disease after pregnancy. Given the one in eight chance of needing further care, women with history of stone disease during pregnancy may benefit from risk counseling, surveillance, or secondary prevention efforts in the postpartum period.