Report of the International Conference on the Perinatal and Infant Mortality Problem of the United States / under the sponsorship of the National Center for Health Statistics, Public Health Service, U.S. Department of Health, Education, and Welfare.

  • United States. Public Health Service.
Date:
1966
Catalogue details

Licence: Public Domain Mark

Credit: Report of the International Conference on the Perinatal and Infant Mortality Problem of the United States / under the sponsorship of the National Center for Health Statistics, Public Health Service, U.S. Department of Health, Education, and Welfare. Source: Wellcome Collection.

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    years from the midpoint of 1950-56 to the mid- point of 1957-63. This was the same rate of decline observed in the total fetal death ratio for the United States. In order to adjust the de- cline in the fetal death ratios of the other States so that a true assessment of the change could be made, Dr. Greenberg assumed that the period after the registration change should have a fetal death ratio lower than that prior to the change at a rate of about 10 percent for every 7 years. This gave him an expected fetal death ratio which, when multiplied by the live births after the change, resulted in the expected number of fetal deaths. Next, he computed a relative increase based upon the observed fetal deaths during the period after the change over the expected fetal deaths. Increases in the ratio of observed to expected fetal deaths would indicate a real change in the total number of fetal deaths reported at 20 weeks or more. Table 2 shows the relative changes. Nine of the States increased, some as little as 3 percent, and two as much as 16 percent. Dr. Greenberg concluded that ifthe European nations were to lower the minimum reporting period to less than 28 weeks, the total number of fetal deaths would probably increase by as much as 4.35 percent. Since the United States registers fetal deaths of 20 weeks or more, any comparison of fetal deaths 28 weeks and over with the European countries would be biased against the United States. When the fetal deaths of 28 weeks and more are examined in order to compare the United States with some of the European nations, the fact that the United States has a lower re- porting period influences the fetal death ratios. A second source of variation in the fetal death ratio arises from differences in determining the period of gestation. Four registration areas in the United States base gestation upon the specified date of last menses, while other areas base it on the weeks of gestation as reported. When New York City changed its method of recording gestation in 1957 and requested that the data of the first day of the last menstrual period (LMP) be reported, so that the length of gestation could be more accurately and consistently calculated, the fetal death ratio at 20 weeks' or more ges- tation increased 24 percent. At the same time, however, the proportion of ''not stated'' gestation periods increased. Discussion brought out the question of whether other factors added to this sharp increase, such as the concentrated cam- paign for better registration which was being conducted by New York City. However, it was resolved that this study was concerned with the immediate effect of the change in reporting the age of the fetus at a time when the influence of the campaign for complete registration was waning. The point to be further studied is that if data for the United States—New York City to be specific—can be increased by as much as one-fourth because of a change in the method of reporting period of gestation, then how is gestation period determined in foreign countries end how does the measurement compare with that of the United States? Dr. Greenberg next discussed tabulation procedures, In the United States, England and Wales, Scotland, and Norway, first-day mor- tality includes deaths within 24 hours after birth. However, in Denmark and the Netherlands, first- day mortality includes only deaths occurring on the calendar day of birth. In order to appraise the effect of this tabulation difference, Dr. Greenberg calculated a separation factor from the distribu- tions of (1) births by hour of birth for a 24-hour period, and (2) deaths by hour of death among those infants dying within the first 24 hours after birth. This separation factor was simply the percent of babies which die within 24 hours after birth and which do not die on the same calendar day of birth. Basedon 108 000 live births in Indiana in 1957 and on the assumption, verified by North Carolina data, that the distribution of first-day deaths approximately follows a simple exponential curve, he estimated the separation factor to be approximately 22 percent, Otherwise stated, deaths within 24 hours after birth exceed deaths occurring on the same calendar day of birth by about 28 percent. However, from Norwegian data of 1949-51 and 1959-61 deaths were tabulated for the peri- ods of 24 hours after birth and for the same calendar day of birth. The two groups of data indicated that 28.5 percent of the deaths within the first 24 hours of life did not occur on the same calendar day of birth. As a compromise,