A recent study showed that Southern-born blacks had the highest mortality rates from hypertension-related diseases, which remained high even when this group migrated to other regions of the United States. Abruptio placentae (premature separation of the placenta), a major cause of third trimester bleeding that can threaten the life of both mother and infant, is often caused by hypertension-related problems in pregnancy, which affect black women at least twice as often as women of other races. Yet, black women born in the South have no greater risk of this obstetric complication than black women born elsewhere.
Apparently, a mother's place of residence rather than place of birth is associated with an increased risk of abruptio placentae. Furthermore, prevalence of risk factors for this problem among black women in a particular region correlates with the rate of abruption in that region, according to a study supported in part by the Agency for Healthcare Research and Quality (HS09788).
Researchers from the University of Medicine and Dentistry of New Jersey examined birth records of all live singleton births among black women in the United States during 1995-1996. They derived age-adjusted rates of abruption for combinations of regions of birth (including foreign-born) as well as regions of residence for these women. The overall incidence of abruptio placentae among black women was 6.7 per 1,000 live births.
The age-adjusted rates of abruption among black women who had not migrated showed that those in the Northeast had the highest rates (8.3 per 1,000), followed by those in the Midwest (6.3 per 1,000), South (6.0 per 1,000), and West (4.9 per 1,000). The prevalence of risk factors for the problem (anemia, intrapartum fever, hypertension, and renal disorders) showed the same pattern. Geographic mapping to better identify variations in the risk of abruption and distribution of risk factors within the Northeast may be the first step in efforts to reduce perinatal morbidity and mortality, suggest the researchers. Their study also showed lower rates of abruption among foreign-born black women (4.0 per 1,000) compared with black women born in any region of the United States.
More details are in "Risk of abruptio placentae by region of birth and residence among African-American women in the USA," by Ambarina S. Faiz, Kitaw Demissie, Cande V. Ananth, and George G. Rhoads, in Ethnicity & Health 6(3), pp. 247-253, 2001.