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16
The figures in the last column show the true relation between maternal age
and risk in childbirth, and may be compared with the death rates from all causes
among all women at the same ages:—
Age
period.
Female death-rate
from all causes
(per 1.000 living,
1911-21).
Mortality of married women
in childbirth excluding
first confinements
(per 1,000 births, 1911-21).
Fertility of married women
according to age.
England and Wales, 1920-21
(births per 1,000 women).
15—
3.2
1.38
447
20—
3.8
1.72
359
25—
4.4
2.51
268
30—
5.0
3.58
197
35—
5.9
5.21
131
40—45
7.0
11.86
32
In the last column is shown the comparative fertility of mothers according to
age in 1920-21 (see annual report of the Registrar-General for 1922, Text, p. 138),
and it will be observed that as the fertility decreases the risk of confinement increases.
The inverse relation of the figures in the last two columns is very close; the observation
on page 13 of the inverse relation of maternal mortality and fertility at different
periods of time therefore applies also to different ages of the mother.
The data given above show that women marrying at 18 and having three
children before the age of 25 years would have on the average a death risk per
1,000 children born of 207; while women marrying at 33 and having three children
before the age of 40 would have a death risk of 5.86 per 1,000 births. The postponement
of marriage in such an instance would presumably nearly treble the
maternal risk per birth.
On the other hand if no women had borne children after the age of 35 in the
period 1911-1921 the total births would have been less by 20.3 per cent. but the
maternal deaths would have been reduced by as much as 340 per cent. Thus birth
control may have a considerable effect upon the maternal mortality rates.
Figures relating to New South Wales during the eight years, 1893-1900, contained
in Sir T. Coghlan's statistical essay on "The Decline in the Birth-rate," pp. 60 and
62, show that the maternal mortality-rate per 1,000 births would have been a
minimum if each married woman had borne four children. The maternal risk in
childbirth of a married woman bearing her first child was equivalent to a mortality of
8'8 per 1,000 births : the average risk among multiparae was as follows:—
Average maternal risk
Children borne. per 1,000 births.
2 6.74
3 6.32
4 6.05
5 6.21
6 6.23
After the fourth child the average risk increases with the number of children.
The life-table for London for 1920-22 shows that the average births per married
woman in that period was only 2.8.
In view of the higher risk of mothers in a first confinement, it is obvious that a
decrease in the average size of the family will increase the proportion of first confinements
and thus tend to increase the rate of maternal mortality when calculated
per 1,000 births. The point is referred to by Dr. Janet M. Campbell in her third
report on Maternal Mortality, p. 6, where a statistical note on the subject by Prof.
Greenwood and Dr. T. H. C. Stevenson is added. It is shown that a population
with a stated proportion of large families may have a maternal mortality rate which
is equal to that of another population in which there are no large families. In
France, where questions affecting fertility have received more attention than in this
country, the number of first confinements is ascertained and it is thus possible to
calculate the effect of varying proportions of primiparae in an actual population.