21. The Abortion Act 1967 originally stipulated a
28 week upper gestational age limit on abortions. That is the
same age that was used in the Infant Life (Preservation) Act 1929
as "prima facie proof that [
] a child was capable of
being born alive". In the 1980s, the Royal College of Obstetricians
and Gynaecologists (RCOG) set up a working party to look at the
survival rates of neonates born before 28 weeks. The working party's
report, Fetal Viability and Clinical Practice (1985), noted
significant progress in neonate survival rates and recommended
that the age at which a foetus should be considered viable should
be 24 weeks. In 1990,
Parliament decided, on a free vote, to amend the Abortion Act
1967 to lower the time limit from 28 to 24 weeks.
22. The term 'neonatal viability' has been subject
to a range of interpretations. At one extreme a baby could be
defined as viable simply because it was born showing signs of
life, for example, breathing or a heart beat, even if it were,
say, an anencephalic newborn which lacked most of the cerebral
hemisphere but was capable of using its lungs.
At the other extreme, it could mean that a baby is capable of
surviving through childhood with no or minimal disabilities.
23. This range of definitions raises related problems
in pinpointing an 'age of viability'. The age of viability could
- the minimum gestational age
at which any neonate could survive;
- the gestational age at which a particular neonate
could survive; or
- the gestational age at which the majority of
neonates could survive.
24. It is important to distinguish between foetal
viability and neonatal viability. Neonatal viability is based
on survival rates among live-born infants, whereas foetal viability
expresses survival in relation to foetuses who are alive and variable
times during the pregnancy.
25. The national EPICure study from 1995 (see paragraph
31) reports that at 20-22 weeks 89% of babies are born dead, while
at 23 weeks, 61% of babies are born dead, dropping to 40% at 24
weeks. Of these,
some would have been dead at the commencement of labour (intra-uterine
death), and can not be included in the denominator for foetal
survival, and the rest would have died during labour. EPICure
1 did not distinguish these two groups, so we can only conclude
from EPICure 1 that foetal survival rates are much lower than
neonatal survival at 22 weeks, significantly lower at 23 weeks
and still considerably lower at 24 weeks.
26. EPICure has traditionally been reported as the
proportion of neonates who survive out of those born alive (or
who have been admitted to NICUs), but not including those who
died during labour. This is therefore neonatal viability, not
27. We took evidence from Professor Neil Marlow,
President of the British Association of Perinatal Medicine (BAPM),
who told us that viability "is the capability of surviving
the neonatal period and growing up into an adult".
Professor John Wyatt, Professor of Neonatal Medicine at University
College London, agreed: "it is the ability to survive and
grow up into adult life with optimal medical care".
28. This use of viability is not the same as the
legislative language: 'capable of being born alive'. However,
as is pointed out in the BMA's paper on Abortion time limits,
some legal cases have also suggested that viability does not equate
solely with being born alive.
29. Gestational age is not the only factor that determines
the likely outcome of an extremely preterm birth. Factors such
as birth weight, whether it is a multiple pregnancy and sex of
the foetus also affect the likely outcome.
Further, there is always a problem that development is continuous
and varies from individual to individual, so any demarcation is
bound to be arbitrary.
The BAPM uses the concept of a 'threshold of viability', which
it puts between 22 and 26 weeks of gestation in the developed
world, and, quoting the WHO, between 22 and 28 weeks in the developing
world. The Nuffield
Council on Bioethics in their recent report uses the same time
period and describes it as "borderline of viability".
EVIDENCE OF MEDICAL ADVANCES
30. Between 1967 and 1990 there were clear advances
in neonatal care which ultimately led to the reduction of the
28 week gestational upper limit to the current 24 week limit.
Since 1990, improvements have continued to be made, and the nature
of these improvements are discussed below.
National and regional studies
31. The most comprehensive analysis of the survival
rates of extremely preterm babies was conducted by the EPICure
group, which is led by Professor Kate Costeloe of Homerton Hospital
in London, Dr Alan Gibson of the Royal Hallamshire Hospital in
Sheffield and Professor Neil Marlow of the University of Nottingham.
The EPICure study looked at every baby born at 25 weeks 6 days
or less gestation in the UK and Ireland between March and December
1995. The health of each child was then assessed at 1 year, 2½
years, 6 years and 10 years. The following table shows the immediate
and 6-year outcomes of premature births, averaged across the UK
2: EPICure - Summary of Outcomes among Extremely Preterm Children