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of cases in this series with more than two pregnancies is not large
(about 450 cases).
If we take into account age as well as parity we get the following
figures:—
Age
Under 30 years. 30 years and over.
First pregnancy 22.35 55.83
Second „ 4.74 13.73
Third „ 22.47 40.20
Fourth and subsequent
pregnancies — 56.33
Risks appear to increase quite definitely with age.
(2) Family Income.
Many observers believe that under-nourishment during pregnancy
greatly increases the risks of abortion, still birth and
premature birth.
For the purposes of this enquiry the cases are grouped according
to the fees payable for accommodation : these fees are based
strictly on family income.
Still births according to the fees charged are shown in the
following table:—
Still birth rate
Fees per 1,000 births
Under £2 a week 23.3
£2 and under £3 28.0
£3 and under £4 17.0
Over £4 a week 35.3
No reliable conclusions can be reached from these figures.
There is one condition which undoubtedly is responsible for
some still births and which has received a lot of attention during
recent years.
Most people now-a-days know that for the purpose of blood
transfusion the donor must belong to the same blood group as the
recipient, because bloods of different groups contain elements which
are incompatible and mutually destructive.
The new factor which has been discovered in the blood in
recent years is known as the Rhesus factor. In about fifteen per
cent, of individuals the blood is Rhesus negative and in the rest it
is Rhesus positive. If a mother is Rhesus negative and her developing
child is Rhesus positive, the positive factor in the child's blood
will cause the production of antibodies in the maternal blood : in
time these antibodies develop to such an extent that they bring
about the destruction of the child's blood cells and cause premature
intra-uterine death. The Rhesus factor is inherited from both
parents, but if the positive factor is present it is the dominant
factor: individuals therefore may be double positive (Rh.Rh.)
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