Pregnancy outcomes in a prospective matched control study of pregnancy and renal disease.

OBJECTIVE: Assessment and comparison of pregnancy outcomes in women with renal disease and women with high risk pregnancies due to medical illness without renal disease.
DESIGN: A prospective, matched controlled study.
SETTING: The High Risk Obstetrical Clinics of Magee Women's Hospital, a primary and referral center where approximately 9,500 deliveries occur per year. PATIENTS: Two groups of pregnant women, all identified in the first trimester. The study group included 43 pregnancies in 40 women with renal disease as defined by: 1) known renal disease antedating pregnancy, 2) prepregnant proteinuria > or = 150 mg/24 hours, or 3) first trimester serum creatinine > or = 0.8 mg/dl or proteinuria > or = 300 mg/24 hours. The 43 controls included women with medical problems other than renal disease that placed them at high obstetrical risk. Control women were matched to study women for parity, advanced maternal age, race, and insulin-dependent diabetes mellitus. MEASUREMENTS: For all patients, blood pressure was recorded once at approximately 10, 20, and 30 weeks gestation. For study patients, serum creatinine, 24-hour urinary protein, and creatinine clearance were obtained at least once in each trimester. Pregnancy outcomes were recorded as favorable if gestation was > or = 36 weeks and without evidence of intrauterine growth retardation. Adverse pregnancy outcomes included prematurity, intrauterine growth retardation, intrauterine fetal death, spontaneous abortion, or neonatal death.
RESULTS: Forty-two percent of study and control patients were diabetic. First trimester renal function was normal (creatinine < 0.8 mg/dl) in 12 study patients, mildly impaired in 24 (creatinine 0.8-1.4 mg/dl) and moderately impaired in 5 (creatinine > or = 1.4 mg/dl). Compared with controls, first and third trimester hypertension was more prevalent in the study patients (p = 0.003, p = 0.012); overall mean blood pressure was also higher in study patients (92 +/- 11 mmHg vs 85 +/- 8 mmHg, p = 0.002). The mean gestational age was shorter in the study patients (33.4 +/- 6.9 weeks vs 37.2 +/- 4 weeks, p = 0.001). Overall pregnancy loss was more common in the study patients (14/43 vs 3/43, p = 0.003) with spontaneous abortion contributing half of those pregnancy losses (7/14). Hypertension in any trimester was associated with adverse pregnancy outcome in study but not control patients. In the subset of study patients, adverse fetal outcome was directly associated with degree of renal dysfunction and proteinuria.
CONCLUSIONS: Pregnancy outcome in women with renal disease was significantly worse than in the control group and showed no improvement over retrospective reports from the 1970's and 1980's. Specifically, fetal deaths were more common in women with renal disease and were predicted by proteinuria and the degree of renal dysfunction. The uncommonly low number of spontaneous abortions in the control group may have contributed to the worse fetal outcome in the study patients compared with controls. Women with diabetes mellitus and hypertension are at particularly high risk for relatively poor pregnancy outcome. These higher risks should be discussed when counseling women with renal disease who contemplate pregnancy.