demographic yearbook annuaire demographique 1951

erly recorded but the registration of births is defective.
Attention is therefore drawn to the reliability code given in
the table as a safeguard against serious misinterpretation
and to the notations concerning the treatment of infant
deaths occurring shortly after birth which also has a strong
effect on the level and comparability of the rates.
The spectacular decline of infant mortality observed in
many areas over the last two or three generations appears
to have continued during the period 1930-1950. A decline
may be seen in almost every series of rates given in table 19.
A grouping of these series in accordance with the level of
the infant mortality rate in the first year (1930) and the last
year shown in most of these series (1949) gives the distribution
shown in Table E.
In 1930 more than half of these countries reported an
infant mortality rate of 100 or more. The maximum rate
observed was 296.7. Nineteen years later, the great majority
of countries-in fact, more than four-fifths of them-had
an infant mortality rate below 100, and almost one-third a
rate below 50. By 1949, the maximum rate of 169.0 was
more than 40 per cent below the former maximum. Among
the lowest rates reported in 1949 were those of 23.9 for
Iceland and 23.3 for Sweden.
The relative decline in the infant mortality rate during
the period in question was not the same in all areas, being
much more rapid in some than in others. In general, areas
with a high initial rate had a larger decline than those with
a low initial rate. This difference results in part from the
fact that infant mortality has two components that have
different causations and follow different trends. Death occurring
during the first few weeks or at most the first month of
life, commonly referred to as "neonatal" deaths, are largely
the result of developmental causes, i.e., causes which began
during the pre-natal stage of life, and to injuries received at
birth or connected with the act of birth. These causes have
so far been difficult to control and the reduction obtained
in neonatal mortality has been slow or negligible. Deaths
occurring after the first month of life are attributable mainly
to environmental and social causes, and can be controlled
effectively with present knowledge and with improvements
of the social and environmental conditions of newborn
children. Consequently, this segment of infant mortality has
declined at a much faster rate than neonatal mortality.
As a result of the difference in the behaviour of the two
components of the infant mortality rate, neonatal mortality
constitutes the major part of the total infant mortality in
areas where the rate is low at present. In areas with a
present high rate of infant mortality, the second component
of the rate is more important; hence there are greater
possibilities for substantial savings of infant lives in the
future. Statistics of infant deaths, classified by subdivisions
InJant
mortality
rate
TABLE E
Number of areas reporting mortality rates
at specified levels-1930 and 1949
1930
--------~------------ ---------
All classes. . . . . . . . . . . . . . . . . . . . . . .. 77
Under 50. . . . . . . . . . . . . . . . . . . . . . 7
50-99 29
100-149 22
150 and over. . . . . . . . . . . . . . . . . .. 19
Median rate 105
Number oj areas
1949
85
25
45
13
2
80
of the first year of life, bring out this inverse correlation
between the level of the infant mortality rate and the percentage
ofinfant deaths that occur before the age of 1 month.
The 54 areas for which statistics for 1945 or a later year
are presented in table 20 have been classified with respect
to these two characteristics and the results are shown in
table F below.
For the 18 countries with rates of less than 50 per 1,000
live births, neonatal mortality constitutes more than 50 per
cent of total infant mortality. Conversely, in 8 of the 9
countries with infant mortality rates of 100 or over, neonatal
mortality amounts to less than 50 per cent of the total.
The lowest percentage is 24; the highest 75.
A corollary of these observations is the comparative stability
ofthe neonatal mortality rate in time, especially among
areas of low infant mortality (see rates in table 21 for the
period 1936-1950). It may therefore be inferred that further
declines of the infant mortality rate in low-mortality areas
will be slow unless new techniques are discovered for controlling
the development of the foetus during pre-natal life
or unless child-birth is made safer for the infant.
Death rates at other ages. The most striking feature of the
age-specific death rates shown in table 17, is the marked
decrease in mortality at almost all ages that has occurred
since the middle of the 1930 decade. A comparison between
1936 or 1937 and a recent postwar year can be made in only
a limited number of cases. All of these are countries which
had already achieved comparatively low levels of mortality
at the beginning of the period under consideration and
where death rates were generally expected to show only
moderate or slow further declines. But the statistics record
decreases as high as 70 per cent at some ages; decreases of
40 per cent or more are frequent (see data for these countries
in table G).
In these 17 countries the greatest reductions occurred in
the death rates of childhood and early adulthood. With
infant mortality perhaps approaching a "biological minimum",
the ages at which mortality is more subject to
environmental control show a greater relative improvement.
Rates for the age group 1-4 years, have fallen to unprecedently
low levels, being less than 2 per 1,000 in 8 of the 17
countries shown in table G and in 11 of the 36 countries
for which postwar data are available in this volume.
Even in the next two age groups (5-9, 10-14), which had
very low rates at the beginning of the period, reductions
were of the order of 40 to 60 per cent. The group 10-14,
commonly the age period of lowest mortality, shows current
InJant
mortality
rate
All areas .
Under 50 .
50-99 .
100-149 .
150 or over .
TABLE
Distribution of 54 areas with respect to the level of the infant
mortality rate and the percentage of infant deaths occurring
in the first month of life
(Data refer to the latest available year)
F
Number oj areas by percentage oj
inJant deaths under 1 month
Under 65
35 35-49 50-64 per cent
Total per cent per cent per cent or over
54 8 22 17 7
18 11 7
27 4 18 5
8 4 3 1
1 1
13