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 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 Baby Chapter 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? There are other methods of contraception which can help prevent pregnancy and it is important to understand which methods are out there. Most do not prevent STIs but they can prevent pregnancy. Abstinence however is still the only way to prevent pregnancy and STIs Not all forms of contraception are 100% affective. If one says 80% affective, that means that there is a 1 in 5 chance that a pregnancy could occur using that method.

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 No two people, except identical twisn, have identical dna

Dominant and Recessive Genes A dominant gene is a stronger gene 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 So if a man fertilizes an X chromosome with a Y chromosome the combination is for a boy. XX is for a girl.

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 Defects Environmental Hereditary 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 Parents can pass off faulty recessive genes This is called recessive inheritance Tay-Sachs disease Cystic Fibrosis Tay-Sachs disease affects the nervous system and causes it to malfunction Cystic Fibrosis when thick mucus builds up in the lungs, digestive track and other areas of the body

Types and Causes of Birth Defects Errors in Chromosomes Interactions of Heredity and Environment 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 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 Tests Alpha-fetoprotein (AFP) Ultrasound 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 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 Chorionic Villi Sampling 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 Uses a sample of tissue from the membrane that encases the fetus to check for birth defects Tissue is cut off and analyzed Newer techniques using a laparoscope are used to take samples and even operate on unborn babies. These procedures currently carry a risk however new technology makes these procedures safe for widespread use in the future.

Chapter 4 Section 3 Avoiding 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 Environmental factors include prescription and over-the counter drugs, caffeine, nicotine, illegal drugs, and inhalants

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 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 Deformity is a defect in a structure

Alcohol Fetal 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 Deformity is a defect in a structure

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 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 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

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 Toxoplasmosis Rubella is also called the German measles Mother contracts it Birth defects can happen within 1st three months Blindness Deafness Heart disease Mental retardation 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 Sexually Transmitted Infections 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 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 AIDS 35-65% it will be passed to the baby. Most babies are delivered by C-Section if the mother is known to have an STI Herpes can cause the child to be born with brain infections or mental retardation. Some can die from the infection.