chapter 4: prenatal development
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Chapter 4: Prenatal Development. 4.1 The Developing Baby 4.2 Problems in Prenatal Development 4.3 Avoiding Dangers to the Baby. Chapter 4 Objectives. List the methods of family planning Outline what occurs during each of the three stages of prenatal development - PowerPoint PPT PresentationTRANSCRIPT
Chapter 4: Prenatal Development4.1 The Developing Baby4.2 Problems in Prenatal Development4.3 Avoiding Dangers to the Baby
Chapter 4 Objectives•List the methods of family planning
•Outline what occurs during each of the three stages of prenatal development
•Contrast miscarriage and stillbirth
•Identify how ten major birth defects can be diagnosed
•Summarize the hazards that alcohol and other drugs pose to prenatal development
•Assess why environmental hazards must be avoided during pregnancy
•Describe how a fetus can be affected by certain illnesses the mother may contract
The Developing BabyChapter 4 Section 1
Family Planning
Many families carefully consider whether to have children and when to have them. However, anytime a couple has sexual intercourse, a pregnancy can occur. The only sure way to prevent pregnancy is abstinence, or avoiding sexual activity.
Do you think this statement is true or false?
Conception
About every 28 days, an ovum (egg) is released by one of a woman’s two ovaries. This is called ovulation; at the same time certain hormones are
released
During ovulation, the inner lining of the uterus grows and thickens. If the ovum is not fertilized, the lining breaks down and passes out of
the body The menstrual period
When an ovum is released it travels through the fallopian tube (connects the ovary to the uterus) This journey takes about 2-3 days
Conception
When the ovum reaches the uterus unfertilized, it typically breaks up
When a sperm, the male cell, reaches the fallopian tube it may penetrate and fertilize the ovum
The process when the sperm fertilizes the egg is called conception
Ovum's usually live 12-24 hours while sperm are capable of fertilizing an ovum for about 48 to 72 hours During a woman’s cycle, there are only about 3-4 days in which
conception can occur
Conception
The Role of Genetics
People inherit many physical traits from their parents Skin color Hair color and texture Eye color Size and shape of ears Much more…
Some children are more likely to have talents like musical talents or athletic ability
The Role of Genetics
At the moment of conception, every human baby receives 46 chromosomes A chromosome is a tiny threadlike structure in the nucleus of every
cell Chromosomes come in 23 pairs
The fathers sperm and mothers ovum contribute 1 to each pair Has hundreds to thousands of gene
A gene is a unit that determines a human’s inherited characteristics
The complete blueprint for the creation of a person is called a genome The complex molecules that make up genes are called DNA
Dominant and Recessive Genes
Dominant A dominant gene is a
stronger gene
Recessive A recessive gene is a
weaker one and will not be expressed
•The terms dominant and recessive only refer to the relationship of genes to each other•What factor determines the characteristic that a person will express is the dominant gene
• EX: Red hair genes often skip a generation because the gene is recessive
•Most traits are influenced by multiple genes• Height, weight, personality, and intelligence
Let’s Practice
Making a Unique Person
Heredity explains why people in some families look so much alike and why some do not EX: one child with brown hair and another with bright
blond hair The gender of the child is
determined at conception Sex chromosomes come in
two types X and Y
Woman carries the X, and the man carries the X or Y
1st Month
At 2 weeks: size of a pin head
Egg attaches to the lining of the uterus
Critical stage for brain and spinal cord development
Internal organs and circulatory system begin to form
The heart begins to beat
2nd Month
Size about ¼” long at the beginning of the month
Face, eyes, ears, and limbs take shapes
Bones begin to form
3rd Month
Size about 1” as the month begins
Nostrils, mouth, lips, and eyelids form
Buds for all 20 baby teeth appear
Fingers and toes almost complete
All organs present but still immature
4th Month
About 3” long; weighs 1 ounce as the month begins
Can suck its thumb, swallow, hiccup, and move around
Facial features become clearer
5th Month
About 6 ½’-7” long and weighs 4-5 oz as month begins
Hair, eyelashes, and eyebrows appear
Teeth continue to develop
Organs are maturing
Becomes more active
6th Month
Size about 8-10” long and weighs 8-12 oz. as the month begins
Fat deposits under skin, but fetus appears wrinkled
Breathing movements begin
7th Month
Size about 10-12” long and weighs 1 ½-2 lbs as month begins
Has periods of activity followed by periods of rest and quiet
8th Month
Size about 14-16” long, 2 ½-3 lbs as the month begins
May react to loud noises with a reflex jerking action
Moves into a head-down position
9th Month
Size about 17-18” long and weighs about 5-6 lbs as month begins
Weight gain continues
Skin becomes smooth as fat deposits continue to form
Movements decrease as the fetus has less room to move around
Acquires disease-fighting antibodies from the mother’s blood
Descends into pelvis, ready for birth
Chapter 4 Section 2 Problems in Prenatal Development
Losing a Baby
Sometimes a baby does not develop normally Sometimes the developing baby dies
Miscarriage is when a baby dies prior to the 20th week of pregnancy
Still birth is when a baby dies after the 20th week of pregnancy About 15% of recognized pregnancies end in miscarriage
Causes are still not medically known
Still birth occurs in about 2% of pregnancies Most common causes are problems with the placenta, abnormal
chromosomes, poor growth, and infections
Dealing with Grief
Most couples feel a long sense of attachment prior to a baby’s birth May go through similar stages of grief that a parent would
to a child that was already born
Parents may blame themselves and feel alone Couples may need support to deal with grief Most couples that experience a miscarriage or stillbirth
still have healthy children later
Birth Defects
A serious problem that threatens a baby’s health, and is present at birth, is called a birth defect
Some are mild that no one would ever know the child has a birth defect Others can result in disabilities or even death
Approximately 120,000 babies are born each year in the US with a birth defect Scientists are still trying to identify some causes
If found, could possibly decrease the occurrence of birth defects
Types and Causes of Birth Defects Some defects cause an
abnormality in the structure of the body EX: extra or missing
fingers/toes
Some defects cause one or more systems in the body to not function properly EX: blindness,
deafness, and mental retardation
Some abnormalities are not discovered until months or years after birth
4 main causes of birth defects currently: Environment Hereditary Errors in chromosomes Combination of
environment and hereditary factors
Types and Causes of Birth DefectsEnvironmental Nutritional balance of the mothers
diet
Any diseases or infection the mother has
Harmful substances; alcohol, over-the-counter medication, illegal drugs, etc.
Some medicines help the mother but hurt the baby
Air pollution
Exposure to X-Rays and high levels of radiation
Hereditary Parents can pass off faulty
recessive genes This is called recessive
inheritance Tay-Sachs disease Cystic Fibrosis
Types and Causes of Birth DefectsErrors in Chromosomes When a baby has too many or too
few chromosomes
Most common birth defect is Down syndrome 1 in 800 children are born with a
form of Down syndrome
When you have too many or too few it can affect the body’s systems Heart defects Leukemia Poor muscle tone Physical growth or motor
development
Interactions of Heredity and Environment When an environmental and
hereditary factors are present Examples
Cleft lip Cleft palate
Heredity and medications
Spina bifida A predisposition,
tendency, are combined medications during pregnancy
Prevention and Diagnosis
Changing of your lifestyle Frequent doctors visits for prenatal check-ups Genetic counseling
Assesses their risk of having a child with a birth defect that is caused by a defect in genes Compiling a family history
Prenatal Tests More than 100 kinds of birth defects can be detected
before birth
Prenatal TestsAlpha-fetoprotein (AFP) Blood test between 15
and 20 weeks
AFP is produced in the liver of the fetus and shows up in the mothers blood
Abnormal levels can indicate a possible birth defect
Ultrasound Is a test that uses sound
waves to make a video image of an unborn baby
Can monitor problems with a baby’s skeletal, circulatory, or nervous system
Usually during their 20th week
Many doctors now do 3D ultrasounds
Prenatal Tests
Amniocentesis The process of withdrawing a
sample of the amniotic fluid surrounding the unborn baby
Often used as a test for Down syndrome with the mother is older than 35 years or older
Also may be completed if uncertain results are obtained from the AFP
Done between the 15th and 20th week
Chorionic Villi Sampling Uses a sample of tissue
from the membrane that encases the fetus to check for birth defects Tissue is cut off and
analyzed
Chapter 4 Section 3Avoiding Dangers to the Baby
Effects of Alcohol and Other Drugs on Pregnancy
Essential parts of good prenatal care is avoiding hazards such as Alcohol Drugs Smoking X-Rays Hazardous chemicals Other harmful substances Infections Environmental Factors
Alcohol Even small amounts can
harm the baby
Doctors do not know the exact amount that can harm a baby Avoid any amounts
when trying to become pregnant
Fetal Alcohol Syndrome
Incurable condition found in some children of mothers that consumed alcohol during pregnancy
1 in 5 babies born with FAS do not live to 1 year old
Those that survive can have problems Delayed physical growth Heart, liver, kidney defects Hyperactivity Facial deformity Mental retardation Learning Disabilities
AlcoholFetal Alcohol Effects
Abnormalities caused by the mother consuming alcohol during pregnancy Suffer less than
children with FAS
Extent of damage is directly related to the amount the mother drinks Binge drinking
increases your risk of having a child with FAS
Prescription Drugs and Over-The-Counter Drugs
Extreme example of unsafe mediation is thalidomide 1950s- to relieve morning sickness After proved harmful, 5,000 babies were born with birth
defects Missing or deformed arms, legs
Some acne medicine has been proven to cause problems Chemicals found in some medications can cause mental
retardation in the first 3 months 4-9 months, OTC drugs can cause slow growth, infections,
and bleeding at birth
Caffeine
Passes easily through the placenta Cause high blood levels of
caffeine for fetus Increases fetal heart rate
and movement
Consumed in large amounts: Miscarriage Premature birth Low birth weight
Can draw fluid and calcium out of the body
Small amounts (2 cups of coffee or soft drinks per day) not a huge risk
Tobacco
Cause: Low birth weight Premature birth
Linked to: Respiratory infections Allergies
Illegal Drugs
Mothers pass their addiction to their baby
After birth, babies must go through a painful period of withdrawal Long-term effects can
be learning and behavioral disabilities
Cocaine causes miscarriage, still birth, and premature births Causes unborn child to have
strokes resulting in brain and heart damage or even death
Low birth weight Smaller heads Risk of seizures Risk of SIDS (sudden infant
death syndrome) Tremors Exaggerated startle response Irritability and
developmental delays Feeding and sleeping
problems
Illegal Drugs
Marijuana and methamphetamine use is liked to low birth weight and premature delivery Breathing problems Poor attention span Drowsiness Heart defects
Environmental Hazards
Two possible hazards to unborn babies include X-rays and hazardous chemicals.
Radiation from X-rays, or from other sources, can cause birth defects If an X-ray is necessary during pregnancy, inform your
medical staff because precautions can be taken Dental X-rays are generally considered safe
Environmental Hazards
Hazardous Substances and Chemicals Paint Pesticides Lead in water or paint Carbon monoxide Mercury found in some fish Solvents, paint thinners, and formaldehyde
Diseases and Infections
Rubella Rubella is also called the
German measles
Mother contracts it
Birth defects can happen within 1st three months Blindness Deafness Heart disease Mental retardation
Toxoplasmosis Caused by a parasite
Most people have immune systems to fight it off Developing babies cannot
Causes: Blindness Hearing loss Learning disabilities Severe cases
Death Long-term learning
disabilities Precautions:
Never clean a cats litter box
Diseases and Infections
Chicken Pox Viral infection
Depending when infection occurs during pregnancy will affect the outcome to the baby
1st half of pregnancy Congenital Varicella
Syndrome Causes scarring of the
skin, limb defects, eye problems
Some cases miscarriage
Sexually Transmitted Infections Passed from mother to baby
For Example: Syphilis can be treated if
caught early to the unborn baby Can cause skin rash or
lesions, bone/facial deformities, deafness, brain damage
2% end in miscarriage, stillbirth, or death