???? Birth Defects - PowerPoint PPT Presentation

1 / 64
About This Presentation
Title:

???? Birth Defects

Description:

Birth Defects Birth defects are defined as abnormalities of structure, function, or body metabolism that are present at birth. 1. General One of the ... – PowerPoint PPT presentation

Number of Views:248
Avg rating:3.0/5.0
Slides: 65
Provided by: GeneralEl7
Category:
Tags: birth | defect | defects

less

Transcript and Presenter's Notes

Title: ???? Birth Defects


1
???? Birth Defects
2
  • Birth defects are defined as
    abnormalities of structure, function, or body
    metabolism that are present at birth.

3
1. General
  • One of the most common worries for
    expectant parents is that something will be wrong
    with their baby.

4
  • Understanding the nature and causes of
    birth defects can help reduce the mystery, fear
    and guilt often associated with them.

5
  • However, most babies are born without
    problems, while most of those who are can have
    treatment that will make them much better, or
    even allow them to lead a normal life.

6
  • An international monitoring programme
    shows that, across Europe, just over 2 per cent
    of babies are discovered at birth to have a
    defect that will affect their ability to survive
    or function normally.

7
  • Some defects are often not discovered
    until later (eg deafness and problems in
    walking).

8
  • There is considerable regional variation
    in the rate of defects seen at birth. Glasgow and
    Dublin have traditionally been black spots, with
    rates over 3 per cent, but these figures are
    falling.

9
  • The number of babies actually born with
    defects is also markedly affected by the
    availability of prenatal screening, and the
    availability of voluntary termination of
    pregnancy in the case of severe abnormalities.

10
2. Forms of Birth Defects
  • Defects of limbs, heart and spinal cord
    represent about half of all abnormalities.

11
  • The most common kinds of defect are
    those affecting the limbs (arms and legs). These
    include missing or extra fingers or toes,
    deficiencies in limb length, and abnormalities in
    positioning, such as club foot.

12
  • Heart abnormalities represent the next
    most common category of defect. Common heart
    defects include 'holes in the heart' where blood
    can pass from one side of the heart to the other.
    Again, these may not all be detected at birth.

13
  • The third most common kind of defect
    affects the spinal cord, such as spina bifida.

14
  • Other defects commonly observed include
    those affecting the face (such as cleft lip and
    palate), problems with the development of the
    intestines and stomach, and problems affecting
    the sexual organs.

15
(No Transcript)
16
Single gene disorder
  • Ploygene disorder
  • Chromosome disorder
  • Mitochondrial disease

17
  • Major chromosomal problems such as Down's
    syndrome (Trisomy 21) are found in about 0.15 per
    cent of births (about three babies in every
    2000).

18
3.The cause of birth defects
  • In ancient times, abnormalities were seen
    as warnings or punishments from the gods. Even
    quite recently, it was believed that specific
    events during the pregnancy - such as being
    frightened by a mouse - would lead to specific
    defects in the baby, eg a mouse shaped birth
    mark. Such folk beliefs still persist in places.

19
  • A. Genetics
  • Genetics play a role in birth defects.
    One missing or faulty gene can cause a birth
    defect.
  • gene mutation
  • Chromosome aberration

20
  • It may be that they are carriers of the
    condition, or that the genetic problem occurred
    for the first time in the cells that gave rise to
    the baby. Known genetic causes account for about
    25 per cent of all abnormalities.

21
  • B. Environment Environmental causes
    (including exposure to drugs, radiation and
    illnesses) can be identified in about 10 per cent
    of birth defects. The risk of exposure to such
    environmental factors often causes great concern,
    although genetic causes are more common.

22
  • There are three main kinds of factor
    that can cause defects chemical, biological and
    physical.

23
  • Chemical factors, including drugs
    Thalidomide is perhaps the most notorious example
    of a drug that caused defects. It was brought on
    to the market after inadequate testing and
    specifically prescribed for pregnant women.

24
  • Treatment for pregnancy reaction
  • untoward effectsdefect of limbs(
  • phocomelia)

25
(No Transcript)
26
  • Following this, much stricter rules about
    drug testing were introduced, and international
    monitoring programmes were put in place. Doctors
    are also much more cautious about prescribing
    drugs to women of child-bearing age, so it is
    unlikely that a disaster on this scale will occur
    again in the UK.

27
  • Several medical treatments pose the risk
    of birth abnormalities.
  • Tetracycline(antibiotic) affect hard tissue
    formation during the foetal period, affecting the
    long bones and teeth.

28
  • Some anticonvulsant medicines used for
    epilepsy may also cause problemshare lip, limbs
    defects, congenital heart disease

29
  • Moderate alcohol use in pregnancy is a
    particularly tricky problem.

30
  • Smoking is bad for the development of
    the baby in a number of ways. Pregnant women
    should not smoke under any circumstances.

31
  • Lack of something may be as damaging as
    the presence of something. Extensive trials have
    confirmed that taking folic acid before pregnancy
    can reduce the number of spinal cord defects such
    as spina bifida.

32
  • poisons pollution

Cri du chat syndrome
33
  • Biological factors, including illnesses The
    rubella virus, which causes German measles, poses
    a serious hazard to the developing baby. It can
    cross the placenta and attack the baby to cause a
    range of defects.
  • The proportion of mothers infected with
    the rubella virus during the first 12 weeks of
    pregnancy who have an abnormal child can reach 20
    per cent.

34
  • cytomegalovirus also cause problems as
  • Enlarged spleen
  • Liver problems
  • Jaundice (yellowing of the skin and eyes)
  • Small size
  • mental retardation,
  • cerebral palsy
  • vision and hearing loss

35
  • herpes simplex
  • 4weeks 61
  • 5-8weeks 26
  • 9-10weeks 6
  • Heart defects deafness cataract

36
  • Bacteria such as salmonella, present in
    undercooked meat (especially chicken), and
    listeria (found in some cheeses), can cause
    problems for the continuation of the pregnancy
    (rather than birth defects).

37
  • Toxoplasma
  • Toxoplasma is a species of parasite
  • The definitive host of the cat, but the parasite
    can be carried by many warm-blooded animals .
  • Toxoplasmosis, the disease of which T. gondii is
    the causative agent, is usually minor and
    self-limiting but can have serious or even fatal
    effects on a fetus whose mother first contracts
    the disease during pregnancy.

38
  • Acute stage Toxoplasma often give flu-like
    symptoms in the early acute stages
  • The acute stage fades in a few days to months,
    leading to the latent stage. Latent infection is
    normally asymptomatic but some induce
    encephalitis, which can be deadly
  • If infection occurs for time during pregnancy,
    the parasite can cross the placenta, possibly
    leading to hydrocephalus or chorioretinitis.

39
  • Physical factors (including radiation)
    X-rays and radiation given as cancer therapy can
    affect the baby. Your medical carers will be very
    cautious about giving you an abdominal X-ray if
    you are pregnant or potentially pregnant (this
    means almost every woman of child-bearing age!).

40
  • C. Other factors The exact causes of the
    remaining 65 per cent of defects are currently
    unclear. Many of these defects arise from an
    interplay of genetic and environmental factors.

41
4. When a baby most vulnerable
  • The time at which the developing baby is
    exposed to a possibly damaging environmental
    factor is more important in determining the
    nature of the likely abnormality than the nature
    of the factor itself.

42
  • In fact, if babies are exposed to the same
    damaging factor at different times in their
    development, the nature of the damage is likely
    to be different.

43
  • For instance, exposure to the rubella
    virus at three weeks after fertilisation may
    cause heart defects, and at six weeks after
    fertilisation, it may cause deafness. Exposure
    radiation at three weeks may cause similar damage
    to rubella.

44
'sensitive period
45
  • Pregnancy is usually timed from the last
    menstrual period, which is generally about a
    fortnight before fertilisation. Three weeks after
    fertilisation to the '10th week of pregnancy'.

46
  • The developing baby is particularly
    vulnerable to environmental factors during a
    five-week period starting about three weeks after
    fertilisation, and lasting till about the end of
    the eighth week after fertilisation.

47
5. Spina Bifida
  • Spina bifida is a birth defect that
    involves the incomplete development of the spinal
    cord or its coverings. The term spina bifida
    comes from Latin and literally means "split" or
    "open" spine.

48
  • caused by the incomplete closure of the
    embryonic neural tube.

49
  • A. Types of Spina Bifida
  • The causes of spina bifida are largely
    unknown. Some evidence suggests that genes may be
    involved. A high fever during pregnancy may
    increase a woman's chances of having a baby with
    spina bifida. Women with epilepsy who have taken
    the drug valproic acid may have an increased risk
    of having a baby with spina bifida.

50
  • Spina bifida occurs at the end of the
    first month of pregnancy when the two sides of
    the embryo's spine fail to join together, leaving
    an open area. In some cases, the spinal cord or
    other membranes may push through this opening in
    the embryo's back. The condition can typically be
    detected before a baby is born and treated right
    away.

51
neural tube
coccyx end
Head end
52
spina bifida occulta
53
  • The vertebrae are not completely closed. The skin
    at the site of the lesion may be normal, or it
    may have some hair growing from it.
  • Many people with the mildest form of this type of
    spina bifida do not even know
  • Back pain.

54
  • meningocele

55


12345 Spinous process Central canal Skin partially covering the neural tube defectSpinal cordDura mater
56
  • the meninges are forced into the gaps between the
    vertebrae.
  • As the nervous system remains undamaged,
    individuals with meningocele are unlikely to
    suffer long-term health problems, although there
    are reports of tethered cord.

57
  • The protruded portion of the spinal cord and the
    nerves which originate at that level of the cord
    are damaged or not properly developed. As a
    result, there is usually some degree of paralysis
    and loss of sensation below the level of the
    spinal cord defect. Thus, the higher the level of
    the defect the more severe the associated nerve
    dysfunction and resultant paralysis

58
myeloschisis (rachischisis)
59
  • 1 Spinous process 2 Spinal cord 3 Dura mater
    4 Skin up to the neural tube defect

60
  • occurs when the spinal canal and backbone do not
    close before birth, causing the spinal cord to
    protrude through an opening in the back. This can
    cause partial or complete paralysis below the
    spinal opening.
  • Patients have loss of function of lower
    extremities and may also have bowel and bladder
    dysfunction.

61
  • Arnold-Chiari malformation

the medulla oblongata
62
anencephalus
63
  • occurs when the cephalic (head) end of the neural
    tube fails to close
  • resulting in the absence of a major portion of
    the brain, skull, and scalp.
  • Children with this disorder are born without a
    forebrain, the largest part of the brain
    consisting mainly of the cerebral hemispheres
  • The remaining brain tissue is often exposednot
    covered by bone or skin

64
END
Write a Comment
User Comments (0)
About PowerShow.com