Saving Mothers' Lives: - Public Health Agency for Northern Ireland

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Introduction and aims, objectives and defi nitions used in this Report
Defi nitions of, and methods for, calculating maternal mortality
The ninth and tenth revisions of the International Classifi cation of Diseases, Injuries and Causes of
Death, (ICD9/10) defi ne a maternal death as “the death of a woman while pregnant or within 42 days of
termination of pregnancy, from any cause related to or aggravated by the pregnancy or its management,
but not from accidental or incidental causes”. This means that there was both a temporal and a causal
link between pregnancy and the death. When the woman died she could have been pregnant at the time,
that is, she died before delivery, or within the previous six weeks have had a pregnancy that ended in a
live or stillbirth, a spontaneous or induced abortion or an ectopic pregnancy. The pregnancy could have
been of any gestational duration. In addition, this defi nition means the death was caused by the fact that
the women was or had been pregnant. Either a complication of pregnancy or a condition aggravated by
pregnancy or something that happened during the course of caring for the pregnant woman caused her
death. In other words, if the woman had not been pregnant, she would not have died at that time.
Maternal deaths are subdivided into further groups as shown in Table 1. Direct maternal deaths are those
resulting from conditions or complications or their management which are unique to pregnancy, occurring
during the antenatal, intrapartum or postpartum period. Indirect maternal deaths are those resulting from
previously existing disease or disease that develops during pregnancy, not due to direct obstetric causes,
but which were aggravated by physiologic effects of pregnancy. Examples of causes of Indirect deaths
include epilepsy, diabetes, cardiac disease and, in the UK only, hormone dependent malignancies. The
Enquiry also classifi es most deaths from suicide as Indirect deaths as they were usually due to puerperal
mental illness although this is not recognised in the ICD coding of such deaths. The UK Enquiry assessors
also classify some deaths from cancer in which the hormone dependant effects of the malignancy could
have led to its progress being hastened or modifi ed by pregnancy as Indirect although these also do not
accord with international defi nitions. Only Direct and Indirect deaths are counted for statistical purposes as
discussed later in the section on measuring maternal mortality rates.
ICD-10 also introduced two new terms related to maternal deaths. One of them is pregnancy
related death, defi ned as the death of a woman while pregnant or within 42 days of the end of her
pregnancy, irrespective of cause. These deaths include deaths from all causes, including accidental
and incidental causes. Although the latter deaths, which would have occurred even if the woman had
not been pregnant, are not considered true maternal deaths, they often contain valuable lessons for
this Enquiry. For example they provide messages and recommendations about domestic abuse or the
correct use of seat belts. From the assessments of these cases it is often possible to make important
recommendations. The ICD coding classifi es these cases as fortuitous maternal deaths. However, in the
opinion of the UK assessors, the use of the term fortuitous could imply a happier event and this Report,
as did the last, names these deaths as Coincidental.
The other new term introduced in ICD-10 is Late maternal death, defi ned as the death of a woman
from Direct or Indirect causes more than 42 days but less than one completed year after the end of the
pregnancy. Identifying Late maternal deaths enables lessons to be learnt from those deaths in which a
woman had problems that began with her pregnancy, even if she survived for more than 42 days after its
end. However, although this category has only been recently recognised in the ICD 10 codes, and then
only for deaths from Direct or Indirect causes, the previous three UK Enquiry Reports had already included
all Late deaths notifi ed to the assessors (including Coincidental deaths) occurring up to one year after
delivery or abortion, as does this.