Virtually every national and international agency involved in statistical assessments of health status, health care, and economic development uses the infant-mortality rate — the number of infants per 1,000 live births who die before reaching the age of one — as a fundamental indicator. America’s high infant-mortality rate has been repeatedly put forth as evidence “proving” the substandard performance of the U.S. health-care system. And now a new report focusing specifically on neonatal mortality (mortality rates in the first four weeks of life) from Mikkel Oestergaard and the World Health Organization (WHO) is being cited as an indictment of U.S. health care, with headlines proclaiming that the U.S. ranks 41st in the world on this measure.
Yet it’s not that simple. Infant and neonatal mortality rates are complex, multifactorial end-points that oversimplify heterogeneous inputs, many of which have no relation to health care at all. Moreover, these statistics gleaned from the widely varied countries of the world are plagued by inconsistencies, problematic definitions, and gross inaccuracies, all of which disadvantage the ranking of the U.S., where accuracy is paramount. Even though Oestergaard’s WHO report lists several “challenges and limitations” in comparing neonatal mortality rates, sensationalized headlines continue to rage about the supposedly poor showing of the United States. The following are a few of the difficulties:
Underreporting and unreliability of infant-mortality data from other countries undermine any comparisons with the United States. In a 2008 study, Joy Lawn estimated that a full three-fourths of the world’s neonatal deaths are counted only through highly unreliable five-yearly retrospective household surveys, instead of being reported at the time by hospitals and health-care professionals, as in the United States. Moreover, the most premature babies — those with the highest likelihood of dying — are the least likely to be recorded in infant and neonatal mortality statistics in other countries. Compounding that difficulty, in other countries the underreporting is greatest for deaths that occur very soon after birth. Since the earliest deaths make up 75 percent of all neonatal deaths, underreporting by other countries — often misclassifying what were really live births as fetal demise (stillbirths) — would falsely exclude most neonatal deaths. Any assumption that the practice of underreporting is confined to less-developed nations is incorrect. In fact, a number of published peer-reviewed studies show that underreporting of early neonatal deaths has varied between 10 percent and 30 percent in highly developed Western European and Asian countries.
Gross differences in the fundamental definition of “live birth” invalidate comparisons of early neonatal death rates. The United States strictly adheres to the WHO definition of live birth (any infant “irrespective of the duration of the pregnancy, which . . . breathes or shows any other evidence of life . . . whether or not the umbilical cord has been cut or the placenta is attached”) and uses a strictly implemented linked birth and infant-death data set. On the contrary, many other nations, including highly developed countries in Western Europe, use far less strict definitions, all of which underreport the live births of more fragile infants who soon die. As a consequence, they falsely report more favorable neonatal- and infant-mortality rates.
A 2006 report from WHO stated that “among developed countries, mortality rates may reflect differences in the definitions used for reporting births, such as cut-offs for registering live births and birth weight.” The Bulletin of WHO noted that “it has also been common practice in several countries (e.g. Belgium, France, Spain) to register as live births only those infants who survived for a specified period beyond birth”; those who did not survive were “completely ignored for registration purposes.” Since the U.S. counts as live births all babies who show “any evidence of life,” even the most premature and the smallest — the very babies who account for the majority of neonatal deaths — it necessarily has a higher neonatal-mortality rate than countries that do not.