Kidney disease and maternal and fetal outcomes in pregnancy.

BACKGROUND: Pregnancy in kidney disease is considered high risk, but the degree of this risk is unclear. We tested the hypothesis that kidney disease in pregnancy is associated with adverse maternal and fetal outcomes. STUDY DESIGN: Retrospective study comparing pregnant women with and without kidney disease. SETTING & PARTICIPANTS: Using data from an integrated health care delivery system from 2000 through 2013, a total of 778 women met the criteria for kidney disease. Using a pool of 74,105 women without kidney disease, we selected 778 women to use for matches for the women with kidney disease. These women were matched 1:1 by age, race, and history of diabetes, chronic hypertension, liver disease, and connective tissue disease. PREDICTOR: Kidney disease was defined using the NKF-KDOQI definition for chronic kidney disease or International Classification of Diseases, Ninth Revision codes prior to pregnancy or serum creatinine level > 1.2mg/dL and/or proteinuria in the first trimester. OUTCOMES & MEASUREMENTS: Maternal outcomes included preterm delivery, delivery by cesarean section, preeclampsia/eclampsia, length of stay at hospital (>3 days), and maternal death. Fetal outcomes included low birth weight (weight < 2,500g), small for gestational age, number of admissions to neonatal intensive care unit, and infant death. RESULTS: Compared with women without kidney disease, those with kidney disease had 52% increased odds of preterm delivery (OR, 1.52; 95% CI, 1.16-1.99) and 33% increased odds of delivery by cesarean section (OR, 1.33; 95% CI, 1.06-1.66). Infants born to women with kidney disease had 71% increased odds of admission to the neonatal intensive care unit or infant death compared with infants born to women without kidney disease (OR, 1.71; 95% CI, 1.17-2.51). Kidney disease also was associated with 2-fold increased odds of low birth weight (OR, 2.38; 95% CI, 1.64-3.44). Kidney disease was not associated with increased risk of maternal death. LIMITATIONS: Data for level of kidney function and cause of death not available. CONCLUSIONS: Kidney disease in pregnancy is associated independently with adverse maternal and fetal outcomes when other comorbid conditions are controlled by matching.