Preeclampisa and Eclampsia, While Often Preventable, Are Among Top Causes of Pregnancy-Related Deaths
Preeclampsia and eclampsia were the third leading cause of pregnancy-related deaths between 1979 and 1992, according to an analysis based on nationwide mortality, birth and hospital discharge data.1 Approximately 1.5 pregnancy-related deaths per 100,000 live births were attributable to preeclampsia or eclampsia during this time period; these conditions were also a factor in 6% of pregnancy-related deaths from other causes. The risk of death from preeclampsia or eclampsia was highest between 20 and 28 weeks' gestation and among black women, women aged 40 years or older, and women who received no prenatal care.
Using the Centers for Disease Control and Prevention's national Pregnancy Mortality Surveillance System, researchers reviewed pregnancy-related deaths that occurred between 1979 and 1992 among women whose pregnancies went to at least 20 weeks' gestation. (Pregnancy-related deaths were those that occurred during a pregnancy or within a year of its completion and were attributable to the pregnancy or associated complications.) All records that listed preeclampsia or eclampsia (with or without chronic hypertension) as the cause of death were classified as deaths from preeclampsia and eclampsia.
Live-birth information from the National Center for Health Statistics was used to calculate cause-specific mortality ratios as the number of deaths per 100,000 live births. In addition, the National Hospital Discharge Survey provided estimates of delivery hospitalizations involving preeclampsia and eclampsia diagnoses between 1988 and 1992; these estimates were used as the denominator in the calculation of case-fatality rates.
In all, 4,024 pregnancy-related deaths were identified for the study period, 790 of them from preeclampsia or eclampsia. These deaths were approximately evenly split between preeclampsia and eclampsia; about half were specifically attributed to cerebrovascular hemorrhage or renal failure (35% and 13%, respectively). Preeclampsia or eclampsia was listed as a contributing condition in 6% of deaths from other causes, including 11% of anesthesia deaths, 7% of cardiomyopathy deaths and 10% of deaths from placental abruption.
Preeclampsia and eclampsia together were the third leading cause of pregnancy-related deaths between 1979 and 1992 (with a mortality ratio of 1.5 deaths per 100,000 live births), following embolism (1.9 per 100,000) and hemorrhage (1.6 per 100,000); the mortality ratio associated with all pregnancy-related causes was 7.5 per 100,000.
The risk of death from preeclampsia or eclampsia increased as women grew older; women aged 40 years or older were more than five times as likely to die from preeclampsia or eclampsia (6.0 per 100,000) as were those between 20 and 24 years of age (1.1 per 100,000). Women in weeks 20-28 of pregnancy were at much higher risk (12.5 per 100,000) than women who had reached their 37th week (0.5 per 100,000). Black women's overall risk was three times that of white women (3.5 and 1.1 per 100,000, respectively); at ages 30-34, the disparity was even greater (5.3 and 1.3 per 100,000, respectively).
Information on prenatal care and live-birth order were available only for women who died following a live birth. For this subgroup, deaths from preeclampsia or eclampsia were more common among women who received no prenatal care (5.9 per 100,000) than among those who received any care (0.8 per 100,000); the protective effect of prenatal care was stronger for white than for black women. Women who had never given birth before or who had already had four live births were more likely to die from eclampsia or preeclampsia (1.4 and 1.7 per 100,000, respectively) than were those who had previously had 1-3 live births (0.7-0.9).
In all, 6.4 deaths from preeclampsia or eclampsia occurred per 10,000 women hospitalized for delivery between 1988 and 1992; women with eclampsia were much more likely to die from their condition (71.6 per 10,000 cases) than were those with preeclampsia (3.4 per 10,000). Black women were 1.4 times as likely as white women to have preeclampsia or eclampsia at the time of delivery, and they were twice as likely as white women to die as a result (case-fatality rates, 13.9 and 6.1 per 10,000, respectively). Women aged 35 years or older had preeclampsia and eclampsia case-fatality rates that were approximately triple those for women younger than 25.
The researchers note that information on maternal and family medical history was unavailable, and that insufficient numbers prevented them from investigating age and birth order as confounders. Further limitations cited are the incomplete ascertainment of pregnancy-related deaths through routine surveillance methods and the possibility of erroneous or inconsistent information about cause of death on death certificates.
According to the investigators, the higher preeclampsia and eclampsia mortality risk and lower benefit from prenatal care among black women may indicate "a disparity in health status and access to and quality of prenatal care," and warrant further investigation. More generally, they note that deaths from these conditions are "often preventable," and stress the need "to develop specific interventions to reduce mortality from preeclampsia and eclampsia among all women."--A. Hirozawa
1. MacKay AP, Berg CJ and Atrash HK, Pregnancy- related mortality from preeclampsia and eclampsia, Obstetrics & Gynecology, 2001, 97(4):533-538.