For a half-century, black women have incurred nearly 4 times as many pregnancy complications as white women, even allowing for age, parity, and educational level. Excessive mortality from a given condition may reflect a higher prevalence, a higher case-fatality rate, or both. The investigators calculated these rates for 5 pregnancy complications—preeclampsia, eclampsia, abruptio placentae, placenta previa, and postpartum hemorrhage. These potentially life-threatening conditions together account for about one-fourth of pregnancy-related deaths. National data sets were used to estimate prevalence and case-fatality rates of these disorders in the years 1988–1999. The prevalence rate was defined as the number of affected pregnant women per 100,000 live births, and the case-fatality rate as the number of deaths attributable to the particular condition for every 100,000 affected women.
Although there were no significant racial differences in prevalence rates, black women with these diagnoses were 2 to 3 times more likely to die than were white women. Black-white prevalence rate ratios ranged from 0.8 to 1.6; none of them differed significantly from unity. In contrast, case-fatality rates for all 5 conditions were significantly higher for black women. Case-fatality rate ratios for black versus white women ranged from 2.4 for placenta previa to 3.3 for postpartum hemorrhage. For each condition, the pregnancy-related mortality ratio for black women was 2.5 to 3.9 times greater than that for whites. And for each condition, at least two-thirds of the difference was ascribed to higher case-fatality rates in black women. A maximum of one-third of the difference for any of the conditions was ascribed to higher prevalence in blacks. The method used to redistribute women whose race was unknown did not substantially influence the results.
The investigators conclude that increased rates of pregnancy-related mortality in black women reflect, to a large extent, higher case-fatality rates. Clarifying the mechanisms that determine the severity of complications and the risk of death—including interactions between biology and health services—might help to identify interventions that improve pregnancy outcomes.