Survival after extremely preterm birth
BMJ 2008; 336 doi: https://doi.org/10.1136/bmj.39559.518391.BE (Published 29 May 2008) Cite this as: BMJ 2008;336:1199All rapid responses
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Professor Modi's editorial (BMJ 31 May 2008) adds value to the debate
at the limits of viability and survival. She cites new data updating
survival figures to 2005. The term gestation and gestational age are used
in the paper and by common usage refer to the length of time from the last
menstrual period to delivery. The true definition of gestation from the OED
is "condition of being carried in the womb during the period between
conception and birth" and this will, by deduction be two weeks less. In
ordinary circumstances this will have no importance in the debate however
the lay press can latch on to babies that survive at 22 weeks from IVF to
delivery and hail these as survivors at 22 weeks gestation. They would be
technically correct using the English definition, though the "medical"
definition of such a pregnancy would be 24 weeks (22 weeks from IVF+2
weeks added amenorrhoea). Common usage is therefore fine provided
absolutely all are using it. There are dangers when there is deviation
between medical and English definitions.
Competing interests:
I have sat on an RCOG committee on beginning of life issues
Competing interests: No competing interests
Dear Peter Saunders,
Many thanks for your query about the publication
of the paper by Field et al and the accompanying editorial. The paper was
not fast tracked and the accompanying editorial was commissioned in the
usual way. Neither Evan Harris nor anyone else beyond ourselves and our
peer reviewers had any hand in the decision making that led to
publication. All research articles and their accompanying editorials are
now published online ahead of print. We have done this for several years
for the research papers and for the past year for accompanying editorials,
and we will shortly be extending this continuous publication model to all
BMJ content. Your question about what types of data should influence the
public policy debate in this area is welcome and I look forward to hearing
other views on this.
Competing interests:
None declared
Competing interests: No competing interests
Dear Sir,
I learnt about this editorial and the article to which it refers when
I was sent an embargoed copy on Thursday 8 May and asked to comment. There
has been huge media coverage since especially in the Independent and
Guardian. However I was somewhat surprised to see that it was not in this
week's paper edition of the BMJ which arrived today.
Why the rush to get it on the web and into the public domain?
The editorial says that upper time limits are to be debated in the
House of Commons this year. What it doesn't say is that they are to be
debated and voted on in just ten days time on 20 May.
So the rush to get this into the public domain was to influence that
debate. This was the same motivation which led to the massive media
coverage around EPICURE 2 just a few weeks ago despite the fact that that
research has not yet appeared in any peer-reviewed journal. And it is
interesting to see that Evan Harris MP, who is leading the parliamentary
campaign to keep the upper abortion limit at 24 weeks is widely quoted in
the newspapers and clearly was alerted very early that this was coming.
Did he perhaps also have a role in pushing this up the BMJ's agenda? It
would be most interesting to know, but I suspect that we never will find
out. The headlines have come and gone and the political opbjectives have
been achieved.
What about the science itself? Is there really no evidence that the
survival of babies younger than 24 weeks has improved? We are told that
Field and colleagues’ data are in keeping with other geographically
defined population studies - and of course they are. The Trent results
show that no babies survived at 22 weeks and less than one in five at 23
weeks.
But the key issue here is whether public policy should be based on
these sort of population studies or on best-practice models.
The Unversity College London results published earlier this year (1)
showed no survivors at 22 or 23 weeks in 1981-85 but 71% (5/7) and 47%
(8/17) respectively in 1996-2000. These numbers may be too small to be
statistically significant but they are highly suggestive of a trend in
centres of excellence that rebuts the major premise of this editorial.
Minneapolis figures in 2005 similarly showed 66% survival at 23 weeks (2).
Furthermore the national statistics for 2005 recently highlighted by
a Parliamentary question and published in the Telegraph confirm that
babies do survive at 22 weeks in parts of the country other than Trent(3).
Department of Health data show that 435 children were born after less
than 24 weeks of pregnancy during 2005. Of those, 52 survived for at least
a year.
The data, for births in England and Wales, showed that eight of the
152 children born after 22 weeks' gestation lived for a year or more. At
23 weeks, 44 of 283 children survived. Of the 201,173 abortions in England
and Wales in 2006, 1,262 were at 22 weeks or more.
So it is clear that nationally in 2005 a significant number of babies
were surviving below the current abortion limit. Even if viability is to
be the sole criterion used for setting that 24 limit (and not any other of
almost 20 reasons given by campaigners (4)) then surely that limit should
come down on the basis that in one year 52 out of 435 babies survived
below the limit and that in centres of excellence at 23 years like UCL and
Minneapolis survival rates are around 50% or better.
References
1. K Riley, S Roth, M Sellwood, JS Wyatt. Survival and
neurodevelopmental morbidity at 1 year of age following extremely preterm
delivery over a 20-year period: a single centre cohort study. Acta
Paediatrica 2008; 97(2)159-165.
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1651-2227.2007.00637.x
2. Hoekstra RE et al. Survival and longterm neurodevelopmental
outcome of extremely premature infants born at 23-26 weeks gestational age
at a tertiary centre. Pediatrics 2004; 113: e1-e6.
http://pediatrics.aappublications.org/cgi/content/full/113/1/e1
3. Many born within abortion limit survive. Daily Telegraph, 18 April
2008. http://www.telegraph.co.uk/news/uknews/1582935/Many-born-within-
abortion-limit-survive.html
Competing interests:
I would like to see the upper limit for abortion come down.
Competing interests: No competing interests
Antecedant events to premature delivery hinder the premature infant
Professor Modi brings us the contemporary views as to survival
following extreme premature birth. These views come from the best
available research. Society is currently interested in at what gestational
age an extremely premature infant has a reasonable chance of survival.
Society is using this gestational age as the point beyond which abortion
should not be allowed.
Babies born at the extreme limits of viability are hindered not only
by their immaturity – they are also affected by the antecedant events that
promoted their delivery. Infection, prolonged membrane rupture, severe pre
-eclampsia, abruptions and the like not only cause the premature delivery,
they have adverse effects on the infant.
Therefore society should not look to the gestational age of babies
that have been exposed to and damaged by adverse ante-natal features to
determine the gestational age of viability. It could be that a well grown
baby, exposed to no adverse forces, electively delivered at 23 weeks could
survive. Until we know this, we should not using the gestation at which
these babies exposed to adverse features survive as the point at which an
undamaged baby might reasonably survive. Nor should we be using the
gestational age at which these damaged babies survive from as the point at
which we allow abortion up to.
Competing interests:
None declared
Competing interests: No competing interests