title: Association of Unilateral Renal Agenesis With Adverse Outcomes in Pregnancy: A Matched Cohort Study.
abstract: BACKGROUND
  Data regarding the effect of a solitary kidney during pregnancy have come from studies of living kidney donors. We evaluated the risk for adverse pregnancy outcomes in women with a single kidney from renal agenesis.
  
  
  METHODS
  Matched cohort study.
  
  
  METHODS
  Using data from 7,079 childbirths from an integrated health care delivery system from 1996 through 2015, we identified births from women with renal agenesis. Only first pregnancies and singleton births were included. After excluding those with diabetes and kidney disease, 200 women with renal agenesis were matched 1:4 by age (within 2 years), race, and history of hypertension to women with 2 kidneys.
  
  
  METHODS
  Renal agenesis defined by International Classification of Diseases, Ninth Revision (ICD-9) codes prior to pregnancy.
  
  
  RESULTS
  The primary outcome was adverse maternal outcomes, including preterm delivery, delivery by cesarean section, preeclampsia/eclampsia, and hospital length of stay. Adverse neonatal end points were considered as a secondary outcome and included low birth weight (<2,500g) and infant death/transfer to acute inpatient facility.
  
  
  RESULTS
  Mean gestational age at delivery was 37.9±2.1 weeks for women with renal agenesis compared to 38.6±1.8 weeks for women with 2 kidneys. Compared with women with 2 kidneys, those with renal agenesis had increased risk for preterm delivery (OR, 2.88; 95% CI, 1.86-4.45), delivery by cesarean section (OR, 2.11; 95% CI, 1.49-2.99), preeclampsia/eclampsia (OR, 2.41; 95% CI, 1.23-4.72), and length of stay longer than 3 days (OR, 1.81; 95% CI, 1.18-2.78). Renal agenesis was not significantly associated with increased risk for infant death/transfer to acute facility (OR, 2.60; 95% CI, 0.57-11.89) or low birth weight after accounting for preterm delivery (OR, 2.11; 95% CI, 0.76-5.88).
  
  
  CONCLUSIONS
  Renal agenesis was identified by ICD-9 code, not by imaging of the abdomen.
  
  
  CONCLUSIONS
  Women with unilateral renal agenesis have a higher risk for adverse outcomes in pregnancy.
authors.affiliation: Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO; Denver Health Medical Center, Denver, CO. Electronic address: jessica.kendrick@ucdenver.edu.
authors.forename: Jessica
authors.initials: J
authors.lastname: Kendrick
authors.affiliation: Intermountain Healthcare, Salt Lake City, UT.
authors.forename: John
authors.initials: J
authors.lastname: Holmen
authors.affiliation: Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO.
authors.forename: Zhiying
authors.initials: Z
authors.lastname: You
authors.affiliation: Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO.
authors.forename: Gerard
authors.initials: G
authors.lastname: Smits
authors.affiliation: Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO.
authors.forename: Michel
authors.initials: M
authors.lastname: Chonchol
mesh_terms: D000328:Adult; D015331:Cohort Studies; D000013:Congenital Abnormalities; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007668:Kidney / Q000002:abnormalities*; D007674:Kidney Diseases / Q000150:complications / Q000151:congenital*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology* / Q000209:etiology*; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000453:epidemiology; D015995:Prevalence; D018570:Risk Assessment
keywords: Solitary kidney; adverse maternal outcome; adverse neonatal outcome; cesarean delivery; eclampsia; gestational age; hospital length of stay; low birth weight; preeclampsia; pregnancy; pregnancy complications; preterm delivery; unilateral renal agenesis