The effect of health maintenance organization vs commercial insurance status on obstetrical management and outcome

Objective: To compare obstetrical management and birth outcomes between patients with health maintenance organization (HMO) insurance and those with private commercial insurance. Design: Retrospective, population-based cohort study. Setting: King County, Washington Patients: Among newborns delivered in 1992 and 1993, a random sample of 4000 birth records listing HMO insurance for prenatal care was compared with a random sample of 4000 birth records listing private commercial insurance as the primary coverage. Main Outcome Measures: Use of ultrasonography and amniocentesis; rate of primary cesarean section performed; adequacy of prenatal care; incidence of maternal medical complications, low birth weight and congenital malformations; and length of hospital stay. Results: Women covered by HMO compared with commercial insurance were more likely to undergo ultrasonography (relative risk [RR], 1.4; 95% confidence interval [CI], 1.3-1.4). Inadequate prenatal care was less frequent among HMO-insured patients (RR, 0.6; 95% CI, 0.5-0.7), as was the incidence of birth weight below 2500 g (RR, 0.7; 95% CI, 0.6-0.9). No differences in rates of cesarean section and congenital anomalies were observed. Among women without obstetrical risk factors. HMO-insured mothers were at an increased risk of labor and delivery complications (RR, 1.4: 95% CI. 1.3-1.5): their infants were at an increased risk of infant distress (RR, 1.8; 95% CI, 1.5-2.2). Conclusions: Patients with HMO insurance have improved access to prenatal care and screening when compared with privately insured patients. The reasons for increased risks of abnormal maternal and infant outcomes observed among a subset of HMO-insured patients are unclear. A study with more detailed prospective data collection is warranted.