Perspectives in Disease Prevention and Health Promotion Enhanced Maternal Mortality Surveillance -- North Carolina, 1988 and 1989

Despite dramatic declines in maternal mortality in North Carolina since the late 1940s, public health officials have continued to characterize the magnitude of and risk factors for maternal death in that state (1,2). In 1989 and 1990, the State Center for Health and Environmental Statistics enhanced its surveillance for maternal mortality by computer-matching birth and fetal-death records with the death certificates of females who had died in 1988 and 1989. This report summarizes the findings of this enhanced surveillance for 1988 and 1989.

The names and dates of birth of females aged 10-50 years who had died in North Carolina during 1988 and 1989 from causes other than cancer or injury were computer-matched to those of females named on birth and fetal-death records during that period. Possible maternal mortality was defined as the death of a female within 1 year of delivering a live infant or within 1 year of a fetal death.

North Carolina's vital statistics system reported 12 maternal deaths in 1988 and seven in 1989, representing rates of 12.3 and 6.9 deaths per 100,000 live births in 1988 and 1989, respectively. The computer-matching process identified an additional 17 possible maternal deaths for 1988; epidemiologic and clinical review of the maternal records by the state\'s maternal mortality review committee suggested that 16 of these women had died of pregnancy-related causes. For 1989, an additional 19 deaths were identified, of which 13 were determined to be pregnancy-related.

Of the 29 additional maternal deaths identified for the 2-year period, four occurred within 1 day of a pregnancy outcome, 13 occurred within 1 week, and 21 occurred within 6 weeks. Review of the multiple cause-of-death codes for these 29 deaths showed that a codable maternal condition had been listed on the death certificate for two of the females. The adjusted maternal mortality rate for the 2-year period (24.0 deaths per 100,000 live births) was substantially higher than the rate based on vital statistics alone (9.5 per 100,000). Reported by: WJ May, MD, Bowman Gray School of Medicine, Wake Forest Univ, Winston-Salem; PA Buescher, PhD, AL Murray, MA, State Center for Health and Environmental Statistics, North Carolina Dept of Environment, Health, and Natural Resources. Statistics and Computer Resources Br, Div of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, CDC.

Editorial Note

Editorial Note: Findings from previous studies have suggested that many deaths related to pregnancy are not identified through vital records (3-5). The assessment in North Carolina demonstrates that more complete counts of maternal deaths can be obtained by linking birth and fetal-death certificates with death certificates of reproductive-aged women. In particular, this study identified pregnancy-related deaths from preexisting or concurrent disease processes that may be adversely affected by pregnancy (i.e., cardiovascular conditions). In addition, the assessment confirmed that most deaths from traditional causes of maternal mortality (e.g., hemorrhage, pregnancy-induced hypertension, infection, and anesthesia) are being identified through the North Carolina vital records system.

Despite the increased identification through the enhanced surveillance approach in North Carolina, there are at least three reasons that some maternal deaths may not have been identified. First, some deaths are not listed in the computerized record of pregnancy outcome (e.g., ectopic pregnancy, induced abortion, spontaneous abortion before 20 weeks\' gestation, or death that occurs during pregnancy). Second, incorrect identifiers (name or date of birth of mother) on either the death certificate or on the birth and fetal-death files may preclude linkage of records. Third, before 1988, the mother\'s date of birth, a key matching variable, was not recorded on birth and fetal-death certificates in North Carolina; consequently, some deaths in early 1988 may not have been identified as pregnancy-related if the pregnancy outcome occurred in 1987.

The matching approach used in North Carolina may be of the most assistance in states without other enhanced surveillance activities. States and localities with enhanced systems may already be identifying some of the additional deaths. For example, the New York City Department of Health has included a specific question on the death certificate to help identify pregnancy-related deaths and routinely traces back to hospital records and autopsy reports to confirm suspected pregnancy-related deaths; consequently, linkage of death files to fetal-death and live-birth certificates has identified few additional maternal deaths in New York City (6). In Oregon, an intensive cause-of-death query program often results in the reclassification of deaths of reproductive-aged women as maternal deaths; hence, that state's maternal mortality rate reported from vital statistics is more than twice the U.S. rate (5). Since 1945, North Carolina has had an active maternal mortality review committee. About half of the additional 1988-1989 pregnancy-related deaths identified by matching had already been identified through that committee's ongoing surveillance.

In the United States, the national vital records system adheres to the World Health Organization definition and classification rules for maternal deaths, which are more restrictive than those used by most states in their maternal surveillance activities; therefore, results from a broader surveillance system may differ from national vital statistics. Enhanced maternal mortality surveillance can augment and expand the important core information routinely available from the vital statistics system (7). At the same time, to increase the accuracy of maternal mortality rates, efforts should be made to promote more complete and accurate certification of cause of death on death certificates (8). Findings from further studies of the etiology of these deaths could be applied to state-based prevention programs.

For additional information regarding the enhanced maternal mortality surveillance system in North Carolina, contact Paul A. Buescher, Ph.D., State Center for Health and Environmental Statistics, P.O. Box 27687, Raleigh, NC 27611-7687; telephone (919) 733-4728.

References

1. May WJ, Greiss FC. Maternal mortality in North Carolina: a forty-year experience. Am J Obstet Gynecol 1989;161:555-61.

2. Buescher PA. Healthier mothers and children through women's preventive health services. N C Med J 1990;51:262-4.

3. CDC. Misclassification of maternal deaths--Washington State. MMWR 1986;35:621-3.

4. New York State Department of Health. Maternal mortality in New York State. Albany, New York: State of New York, 1988.

5. Hopkins DD, Grant-Worley JA, Bollinger TL. Survey of cause-of-death query criteria used by state vital statistics programs in the US and the efficacy of the criteria used by the Oregon Vital Statistics Program. Am J Public Health 1989;79:570-4.

6. Allen MH, Chavkin W, Marinoff J. Ascertainment of maternal deaths in New York City. Am J Public Health 1991;81:380-2.

7. Zemach R. What the vital statistics system can and cannot do (Editorial). Am J Public Health 1984;74:756-8.

8. Rosenberg HM. Improving cause-of-death statistics (Editorial). Am J Public Health 1989;79:563-4.

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