1957 - United Nations Statistics Division

cluded in the total deaths under 1 year and set forth in a
footnote.
It should be noted that the age classification used is not
in accord with the current international standard. In
defining infant deaths for purposes of cause-of-death
statistics and in standardizing the age classification for
special statistics of infant mortality, the World Health
Organization and the United Nations have recommended
31 that deaths under 4 weeks, i.e., under 28 days,
be considered as mortality of newborn or early infancy.
However, since many countries have not yet adopted this
standard and since those that do tabulate infant deaths
according to this classification did not initiate the revised
procedure before 1950 or 1951, it was considered more
convenient to show the calendar-month class and footnote
the 4-week exceptions. This will be apparent in Table
12. For Austria, Finland, and Norway, it was possible to
include data for the same .year tabulated according to
both classifications; these overlapping series are separated
by a horizontal rule in the table. These data, therefore,
enable an evaluation to be made of the probable effect
of the change.
Since data in Table 12 are for males and females separately,
but not for both sexes combined, deaths of unstated
sex are of necessity excluded from the statistics
but are given in footnotes in all cases. Statistics not available
by sex are shown under "male" preceded by a new
box-head specifying "both sexes". Discrepancies of unknown
origin between these and data in Tables 10 and
9 are indicated in footnotes.
Coverage: Statistics of infant deaths by detailed age are
presented in Table 12 for 118 geographic areas. These
include sovereign and non-sovereign countries and data
for ethnic groups or geographic sub-divisions when nothing
else was available. The latter frequencies are shown
in smaller type to aid in distinguishing them from national
coverage.
Limitations: These data are subject to all the general qualifications
of vital statistics set forth on p. 23. Of particular
concern are limitations of completeness due to underregistration
of deaths (see code on Table 9) and variations
in definitions which result in the exclusion of the
deaths of infants who die before registration of birth or
before completion of 24 hours of life. This latter qualification
affects total infant deaths, those under 1 day of
age, and even those up to 3 or more days, depending on
the statutory time allowed for registration of death. For
relative numbers of such infants, see Table 7's footnotes
to Guadeloupe and Martinique.
Limitations in comparability due to differences in
classification by age have been noted above in the discussion
of "under I month" versus "under 4 weeks". Variations
in the method of reckoning infant age at the time of
death also exist; it is an important consideration with
respect to age intervals up to one week. In general, the
age at death is determined on the basis of the time
elapsed after birth (hours, minutes, days, as appropriate)
and is expressed in completed units of time. In some
cases, however, the age is expressed to the nearest day
or is based on calendar days, the calendar day of birth
31 Regulations No. I of the World Health Organization, Article 8;
United Nations PrincijJles for a Vital Statistics System, op. cit.,
Principle 410 (e) (15).
81
being counted as the first day of life and infants dying
the day after birth being classified as I day of age even
though they may have died less than 24 hours after birth.
Age classifications known to be expressed in other than
completed units of time reckoned from the exact time of
birth, are noted in the table. This factor is disregarded
for age intervals of one month or over.
Table 13
Annual rates of infant mortality by detailed age for
each sex and both sexes combined are presented in Table
13. This table corresponds to, and has been based on,
Table 12 and covers the same period-1948-1956. As in
the case of Table 12, this table last appeared in the 1951
Demographic Yearbook, where rates for the period 1936­
1949 were set forth. The present table has been designed
to extend this time coverage to 1956.
As noted in connexion with Table 12 above, infantmortality
rates by detailed infant age provide an extension
of rates in Table 11 to newborn and infancy ages.
The importance of these data for analysis of mortality
has been set forth in the text to the frequency table.
The age classification used in Table 13 is the same as
that employed in the base Table 12 and for the same reasons.
Sub-divisions by age are 5, namely under 1 day, 1
day - under 1 week, 1 week - under 1 month, 1-5 months,
and 6-11 months. Unknown age is included only in the
rate for age under 1 year. For Austria, Finland, and
Norway, rates for both "under 1 [calendar] month" and
"under 4 weeks" have been computed on the same year's
data so that the effect of the classification revision may
be evaluated.
Deaths of unstated sex are included in the rates for
both sexes in this table and, hence, the rate for both sexes
combined, shown in the first column of the table, should
agree with the conventional infant mortality rate shown
in Table 9. Discrepancies of any magnitude are indicated
in footnotes.
Coverage: Rates are available for 108 geographic areas.
The criterion for rate computation was a total frequency
of infant deaths for both sexes combined of 50 or more.
National and sub-national figures are included when this
criterion was met.
Rate computation: Rates are the number of deaths of the
specified age and sex which occurred in the year per 1,000
live births of the same sex during the same period. Thus,
the base of each age-sex rate is the same as that of the rate
for all ages of the same sex, and no adjustment was made
to take account of the fact that some of the deaths were
those of infants born not in the current year but in the
preceding one. Live births used in the denominator of
the rates for both sexes are those presented in Table 6.
Limitations: Although infant mortality rates by detailed
age are of course subject to all the limitations noted in
connexion with vital statistics (see p. 23), perhaps the
most important is that which results from tabulation of
live births by date of registration rather than date of
occurrence. The implications of this procedure have been
set forth in connexion with Tables 6 and 9 above, to
which reference should be made.
Underregistration of births and deaths, as indicated in
the quality codes appended to Tables 6 and 9, also