Sm. Sci. Med. Vol. 35, No. 5, pp. 739-140, 1992 Printed in Great Britain. All rights reserved

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RESEARCH INFANT MORTALITY

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0277-9536192 $5.00 + 0.00 1992 Pergamon Press Ltd

NOTE

AND ILLEGITIMACY

DAVID LIWER Center for the Study of Suicide, RR41, 5 Stonegate Court, Blackwood, NJ 08012, U.S.A.

Abstract-The

changing rate of infant mortality over time in the U.S.A. from 1940 to 1986 and the variation in the infant mortality rate over the states were both found to be associated with the illegitimacy rates. Key words-infant

mortality, illegitimacy

The fact that the U.S.A. has a much higher infant mortality rate than other developed nations has been

a puzzle for many years. In 1987, for example, the infant-mortality rate in the U.S.A. was 50% higher than that in the Netherlands and twice as high as that in Japan. In a review of research on this problem, Eberstadt [l] noted that this increased infant mortality rate in the U.S.A. could not be explained by the high infant mortality rate among African-Americans since the rate was high for white Americans also. Medical care in the U.S.A. also appeared unable to explain the high infant mortality rate since, for any given birth weight, American babies have a higher chance of survival than babies in many other industrialized nations. Instead what appears to be critical in America is the high percentage of babies born with very low birth-weights. Many factors affect the birth weight of babies, including the mother’s age, education and income, race, poverty, the mother’s smoking behavior, unwanted children, and illegitimacy. Eberstadt concluded that illegitimacy was the most important factor since it increased the proportion of low birthweight babies which in turn resulted in a high infant mortality rate. This association has been confirmed in a study of individual babies born in eight American states [l]. Eberstadt noted that unmarried mothers are far less likely to seek prenatal care than are married mothers, and this difference may be responsible for the low birth-weights and high mortality rates. The present study was designed to explore whether the illegitimacy hypothesis could explain the variation in the infant-mortality rate in the U.S.A. both over regions and over time.

National Center for Health Statistics, for the period 1940-1986. The times series regression was carried out using a package provided by Doan [2] using the Cochrane-Orcutt method to correct for serial autocorrelation. For the regional analysis, data for the 48 continental states of the U.S.A. in 1980 were used: the illegitimacy rate, the percentage of black residents, the percentage of people living in poverty, and the percentage of 15-19 year-olds not finishing elementary school were obtained from the 1980 Census data and the infant mortality rates for babies aged zero to 27 days from the Vital Statistics of the United States, 1980. RESULTS AND

DISCUSSION

For the time series analysis, year and illegitimacy were examined for their impact on infant mortality. Infant mortality was negatively associated with the year (Pearson r = -0.98) and illegitimacy rate (r = -0.94), indicating that the infant mortality rate declined in recent years and was lower in years when the illegitimacy rate was lower. In the full multiple regression, both variables contributed significantly to the multiple R of 0.99: for year b = -0.183, P = 0.015 and for illegitimacy rate b = -0.043, P = 0.003. The correlation between infant mortality rates and illegitimacy rates over the states was 0.80 (P < O.OOl), indicating that infant mortality rates were higher in states where illegitimacy rates were higher. Infant mortality rates were also associated with the percentage of African-American residents (r = 0.85), the percentage of people living in poverty (I = 0.38) and the percentage of 15-19 year-olds not finishing elementary school (r = 0.42). In the full multiple regression, only illegitimacy and the percentage of black residents contributed significantly, and the multiple R was 0.87. In conclusion, since research on individuals had indicated that the high rate of infant mortality in the U.S.A. might be a result of the high incidence of illegitimate births, which results in poor prenatal care

METHOD For the time series study, data on the illegitimacy rate (the percentage of births to unmarried women) and the perinatal mortality rate (for infants aged 0 to

27 days) were obtained from the annual volumes Vital Statistics of the United States, published by the 739

740

DAVIDLESTER

and low birth weights, the present study examined whether illegitimacy rates could account for the varying infant mortality rate in America over time and over regions. It was found that indeed infant mortality rates could be accounted for by the illegitimacy rate, though other factors were also important such as the percentage of black residents in the regions and the year for the time-series analy-

sis (perhaps care).

an indication

of improving

medical

REFERENCES 1. Eberstadt

N. America’s infant-mortality

puzzle. The

Public Interesr 105,30-47, 1991. 2. Doan T. A. Regression Analysis of Time Series. Var

Econometrics, Evanston, IL, 1990.

Infant mortality and illegitimacy.

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