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

For the past nine years, ONS have been able to match death records of women of fertile age living in
England and Wales with birth registrations up to one year previously. The aim is to identify deaths of all
women in England and Wales who died within one year of giving birth and to see how many additional
cases can be found. The methodology, used in the past two triennia, was again applied for this Report
and again shows that the majority of these deaths occurred Late, i.e. some months after delivery. The vast
majority of these Late deaths were due to Coincidental Late causes and these are shown in Chapter 14.
Denominator data used for calculating mortality rates
Number of maternities
It is impossible to know the exact number of pregnancies which occurred during this or any preceding
triennium since not all pregnancies result in a registered live or still birth. Because of the unreliability of
these data, due to the lack of appropriate denominators, the most common denominator used throughout
this and previous Reports is the number of maternities rather than the total number of pregnancies.
Maternities are the number of pregnancies that result in a live birth at any gestation or stillbirths occurring
at or after 24 weeks’ completed gestation and are required to be notifi ed by law. The total number of
maternities for the United Kingdom for 2003-05 was 2,113, 831.
Estimated pregnancies
This denominator is used for calculating the rate of early pregnancy deaths. It is a combination of the
number of maternities, together with legal terminations, hospital admissions for spontaneous miscarriages
(at less than 24 weeks’ gestation) and ectopic pregnancies with an adjustment to allow for the period of
gestation and maternal ages at conception. The estimate for the United Kingdom 2003-05 was 2,898,400.
However, the resulting total is still an underestimate of the actual number of pregnancies since these
fi gures do not include other pregnancies which miscarry early, those where the woman is not admitted to
hospital, or indeed those where the woman herself may not even know she is pregnant.
Table 2
Maternal mortality defi nitions used in this Report
Maternal mortality defi nitions Reasons for use
UK Enquiry maternal mortality rates; Direct and
Indirect deaths per 100,000 maternities
The internationally defi ned Maternal Mortality
Ratio (MMR); Direct and Indirect deaths per
100,000 live births
Deaths from obstetric causes per 100,000
estimated pregnancies.
The most robust fi gures available for the UK and used
for 50 years trend data in this Report.
For international comparison although care needs to be
taken in its interpretation due to the more accurate case
ascertainment in the UK though the use of this Enquiry.
Because the data from spontaneous abortions and
ectopic pregnancies are unreliable this denominator
is only used when calculating rates of death in
early pregnancy.
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