Transcript Chapter 4.2 * Problems in Prenatal Development

Chapter 4.2 – Problems in Prenatal
Development
Losing A Baby
 Miscarriage – when the developing baby
dies prior to the 20th week of pregnancy
 Fairly common
 15% of recognized pregnancies end in
miscarriage
 The cause is usually not known
Losing A Baby
 Stillbirth – when the developing baby dies
after the 20th week
 Occurs in about 1% of pregnancies
 Most common causes are problems with the
placenta, abnormal chromosomes, poor
growth, and infections.
Dealing With Grief
 The loss of a child can be very unexpected
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and painful
Often go through stages of grief similar to
those experienced by the loss of a child that
was already born
May feel alone or may blame themselves
Most cases – the death was completely out
of the parents’ control
Still able to healthy children later on
Birth Defects
 Birth Defect – a serious problem that
threatens a baby’s health, and is present at
birth.
 Approximately 120,000 babies are born each
year in the United States with a birth defect.
 Scientists and medical professionals are
working hard to understand the causes of
birth defects.
Types and Causes of Birth Defects
 Not all birth defects are obvious at birth
 Some may cause an abnormality in the
structure of the body
 Some may cause one or more systems of the
body to not function properly
 Scientists do not full understand the causes
for most birth defects, but they have found
four main causes.
Four Main Causes of Birth Defects
 Factors in the environment
 Hereditary factors
 Errors in chromosomes
 A combination of environmental and
hereditary factors
Environmental Causes of Birth
Defects
 The nutritional balance of the mother’s diet
 Any diseases or infections the mother has during
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pregnancy
Harmful substances the mother consumes such
as alcohol, over-the-counter medications,
tobacco, and illegal drugs
Some medicines that benefit the mother but hurt
the baby
Air pollution
Exposure to X-rays and high levels of radiation, or
to certain chemicals such as solvents and
pesticides, especially in early prenancy.
Hereditary Causes
 Every person has approximately 20,000 to
25,000 genes that determine traits
 Genes direct the growth and development
of all the body systems
 Recessive inheritance – when a child
receives two copies of a faulty recessive
gene that causes some type of birth defect
 Tay-Sachs disease
 Cystic Fibrosis
 Dominant inheritance – when a child
receives one defective dominant gene
 Huntington’s disease – does not appear until
middle age
Errors in Chromosomes
 Several types of birth defects are caused by
problems in the number or structure of
chromosomes.
 An error may occur when an egg or sperm
cell is developing.
 Can cause a baby to have too many or too
few chromosomes
 Or have broken or rearranged chromosomes
 Down Syndrome – an extra copy of
chromosome 21
Interaction of Heredity and
Environment
 Some birth defects are caused by a
combination of heredity and environment
 Child may inherit a tendency that may later
lead to a heart defect
 If a factor such as drug use or a virus affects the
baby during pregnancy it will have the heart
defect
 If the baby didn’t inherit the gene and get exposed to
the drug or virus then it wouldn’t have the heart
defect.
 Examples: Cleft lip, cleft palate, spina bifida
Prevention and Diagnosis of Birth
Defects
 Quit smoking and drinking is there is a
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possibility of pregnancy
Visit the doctor for prenatal care
Avoid alcohol, drugs, and tobacco the entire
pregnancy
Only take medications approved by doctor
Genetic Counseling
Prenatal Testing
Genetic Counseling
 Some family doctors may be able to perform
genetic counseling but usually referred to a
genetic counselor
 Examined by genetic counselor:
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Family History
Medical History
Diseases
Causes of death in the family
Physical Exam
Blood samples
Body tissue samples
Prenatal Tests
 Alpha-fetoprotein (AFP)
 Ultrasound
 Amniocentesis
 Chronic Villi Sampling
 New Prenatal Diagnosis