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When a child is born with a limb deficiency, parents often express concern
about medicines taken in pregnancy. Joanne Rowe goes in search of evidence
as to whether antibiotics could be to blame for limb deficiencies.
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When a child is born with a limb deficiency it is almost inevitable
that the baby's family will search for a cause. Unfortunately, for
the vast majority of Reach parents, the health experts are unable
to give an explanation. This invariably means that we look back
over the pregnancy and try to pinpoint things we may or may not
have done which could have affected our unborn babies.
Since the thalidomide scare drugs have been the most obvious target
for possible blame when a child is born with abnormalities. This
raises the question as to whether the prescription or over-the-counter
medicines, in particular antibiotics, that mothers took during pregnancy
could have caused their child's limb deficiency.
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One such mum was Eva Smus, whose son Yiddi was born with only part of
his left palm and finger buds present. When Mrs Smus was between six and
eight weeks pregnant she became ill with tonsillitis and her doctor prescribed
antibiotics. Mrs Smus had taken the recommended folic acid supplements
and only had two or three paracetamols during the rest of her pregnancy
so when Yiddi was born she was convinced his limb deficiency was the fault
of the antibiotics.
"It was the first thing that came into my mind. It was the only
thing," she said.
And she says the doubt about the antibiotics will always be at the back
of her mind until the cause of limb deficiency is proved.
Thalidomide
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Sadly, no one knows for definite that drugs cannot cause limb deficiency
but here we try to look at the available evidence, although this
is very slight, and find out the views of health professionals.
According to Judy Priest, author of "Drugs in Conception,
Pregnancy and Childbirth" until the mid 1950s there was a fantasy
that drugs could not harm unborn babies and could only be beneficial.
Laws governing the testing and sale of drugs were lax and so when,
in the 1960s, the anti-morning sickness drug thalidomide was found
to have caused terrible damage to thousands of babies, it came as
a dreadful shock and the world became wary of drugs.
These days laws are tighter governing the testing of drugs and
GPs are cautious about prescribing them to pregnant women.
The British National Formulary states "drugs should only be
prescribed during pregnancy if the expected benefit to the mother
is thought to be greater than the risk to the foetus, and all drugs
should be avoided if possible during the first trimester."
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Effects of drugs in pregnancy unknown
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Alarmingly, according to Mrs Priest, two thirds of all
drugs available on prescription have no background data about their
effect on pregnant women and unborn babies and drug companies face
major problems when it comes to deciding whether new products are
safe for use in pregnancy. Tests can be done on animals but there
are ethical as well as practical considerations which mean tests on
pregnant women cannot be done.
Even so, Mrs Priest thinks today's drugs are an unlikely cause of
limb deficiency. "If there are, say 3,200 women giving birth
it is likely that one of them might have something wrong with their
baby that is caused by a drug. In most of that the drugs which would
be given would be prescription drugs for a significant illness like
epilepsy or alcoholism," she said. "So the chances of you
and me who are fine, OK, straightforward women, doing anything that
would have caused a deficiency in our babies is so tiny that it doesn't
bear thinking about."The cause is more likely to be one of the
700 or so chemicals that are invented every year for everything else
that we can't avoid because we live here in this world. "Mrs
Priest stresses that if a mother is ill and does not take a drug to
help alleviate her symptoms this could also put the unborn child at
risk and the two factors need to be balanced when deciding whether
to take medicine. |
It is a point backed up by Dr Mark Denman Johnson, the Isle of Wight
GP who is currently carrying out a study into the possible causes of limb
deficiency.
He mentioned that some studies of pregnant animals have shown that high
fevers could have an effect on their unborn offspring, although this has
not shown up in his own study of children with limb deficiencies. He stressed
that it is also difficult trying to establish whether a drug has caused
a limb deficiency because of problems deciding whether it was the drug
at fault or the illness for which it was taken. However, he added that
he has found no evidence that antibiotics have caused limb deficiency.
In 1992 less than one in 100 babies was born with a congenital malformation
and, of these, less than one percent could be directly linked to prescribed
or over the counter drugs.
Increasing use of antibiotics
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Mrs Priest's book states that recent studies have shown 80 percent
of women take one or more drugs while they are pregnant and it is
estimated that 10 percent of pregnant women are prescribed antibiotics.
With the increased use of antibiotics over the last 50 years health
professionals agree that if they had been to blame for limb deficiency
then limb centres would have been seeing children with limb deficiencies
in rising numbers.
Dr Herbert Day, former senior medical officer at the Manchester
disablement services centre and chairman of the Amputee Medical
Rehabilitation Society working party which produced the recommended
standards of care for congenital limb deficiency, kept records which
prove the numbers of children born with limb deficiencies over a
30 year period have remained constant. In the decade up to 1968
there were 106 children referred to the centre with transverse upper
deficiencies, 112 in the following decade and 113 in the 10 years
up to 1988. Longitudinal deficiencies follow a similar pattern with
23, 21 and 27 referrals each decade and lower limb deficiencies
seen were 41, 34 and 33 over the same time periods.
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Scepticism
He is sceptical that a drug or toxin could have caused the deficiencies
which, in most of our children, affects just one limb. "If you take
a poison how can it affect half your body? This seems to me to be the
classic thing that is against unilateral abnormalities coming from some
sort of toxic agent," said Dr Day.
To back up his point he added that in the cases recorded of thalidomide
victims, all had bi-lateral longitudinal deficiencies, affecting either
all four limbs or both upper limbs. None were affected on only one side.
Understanding how the foetus develops is the key to discovering what
went wrong in our children's case, but unfortunately research has not
progressed far enough to give us the answers.
A minority of limb deficiencies do have recognised causes. These are where
the individual has an inherited genetic disorder, a syndrome such as Poland
syndrome or Cornelia de Lange syndrome, there are rare cases of chromosomal
abnormalities and the known toxic agents such as thalidomide as previously
mentioned.
More questions remain
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The majority of remaining limb deficiencies are mainly transverse
in nature and it is still unknown why the left side is affected
twice as often as the right, why it is more common in girls than
boys and why a deficiency just below the elbow is the most common
whereas one just below the knee is extremely rare. These differences,
Dr Day argues, point away from drugs being the cause and he believes
scientists will eventually discover the responsibility lies with
genes.
"It would be very facile and simplistic to say that the development
of limbs is a complicated process and it is amazing it doesn't go
wrong more often," he said.
"We are finding out gradually that more and more of our health
is determined by genetic peculiarities."
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Further reading:
"Drugs in Conception, Pregnancy and Childbirth" by Judy Priest
is published in paperback by Thorsons priced £9.99.
"Congenital Limb Reduction Defects, Clues from developmental biology,
teratology and epidemiology" by Nigel Brown, Judith Lumley, Cheryll
Tickle and Janet Keene is published by The Stationery Office priced £19.99.
This is a major academic work aimed at health professionals.
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