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