Prenatal Development

Prenatal Development Germination Stages of Prenatal Development Genetics Inherited Diseases Neonates

Germination Humans start off as a single cell organism: • Gametes: The male/female reproductive cells • Zygote: Formed an hour after the sperm enters the ovum when the two gametes fuse • Genes: Blueprints for creating a person • 25,000 of them • Composed of DNA molecules _______________________________________________________________ Deoxyribonucleic Acid: (DNA) • Located along 46 chromosomes which are organized in 23 pairs. • Each parent provides 23 chromosomes. • Possible combinations are limitless. • Nearly all of the cells of the body will contain the same 46 chromosomes as the zygote.

Prenatal Development Typically divided into Trimesters: • First: Conception to 3 months • Second: 3 to 6 months • Third: 6 to 9 months The division of pregnancy into trimesters is arbitrary and has no significance with regard to prenatal development.

Prenatal Development Conception • Occurs the moment a sperm cell fertilizes the ovum (egg cell), forming a single-celled zygote.

Prenatal Development Three Stages of Prenatal Development: • Germinal (2 weeks) • Begins with conception. • Takes place in one of the fallopian tubes. • Zygote travels to the uterus and attaches itself to the uterine wall. • Rapid cell division occurs • Once the zygote is successfully attached the germinal stage is over. • Embryonic (6 weeks) • Developing embryo forms all the major body systems, organs, and structures. • Lasts from the beginning of week 3 through week 8. • Begins when the zygote attaches itself to the uterine wall. • Ends when the first bone cells form. • 1 inch long and weighs 1/7 of an ounce. • Embryo already resembles a human being. • Fetal (38 weeks) • Lasts from week 9 (when first bone cells form) until birth. • Experiences rapid growth and further development of body structures, organs, and systems.

Prenatal Development • Teratogen (any agent that causes birth defects): • Drugs (prescription, nonprescription) • Alcohol, tobacco • Environmental pollutants • Infectious diseases • Nutritional deficiencies • Maternal stress • Advanced age of a parent • Severity of damage to the unborn depends on: • Dose • Time of exposure • Genetic susceptibility

Teratogens and Timing of Their Effects on Prenatal Development Zygote Embryonic period (wks) Fetal Period (wks) Central nervous system Heart Arms Most serious damage from teratogens in first 2-8 wks Eyes Legs Ears Teeth Palate Period of susceptibility to structural defects External genitalia Period of susceptibility to functional defects

Prenatal Development • Fetal alcohol syndrome: • Abnormalities in newborn due to mother’s heavy use of alcohol in pregnancy • Abnormalities include: • Facial deformities • Defective limbs, face, heart • Most are below-average intelligence • Some are mentally retarded • Moderate drinkers during pregnancy have babies who were less attentive and alert even at 4 years of age.

Prenatal Development • Maternal smoking can cause: • Respiratory problems • SIDS • ADHD • Low birth weight

Prenatal Development • Illegal drugs that harm during pregnancy: • Cocaine (norcocaine) • Marijuana • Heroin • Incompatible blood types (Rh factor) • Environmental hazards • exposure to radiation or chemicals • STDs, HIV infection, AIDS • Mother to child transmission of HIV is a serious issue in Africa today.

Multiple Births Less than 3% of all cases result in twins • Any more is far less Two types of twins: • Monozygotic (Maternal twins): Identical • Dizygotic (Fraternal): Completely different individuals Mothers carrying multiple children run a higher risk of premature delivery and birth complications.

Is it a boy or a girl? 23 matched pairs of chromosomes: • 22 of them copy their pair. • 23rd chromosome: • Determines sex • XX: females (Two matching, relatively large chromosomes) • XY: males • Female contributes an X chromosome. • Male can contribute either an X or a Y. • If the father contributes a Y chromosome then the infant will be male. • Father who determines the sex of the child.

Genetics Genetics and Traits: • Dominant: • Expressed trait when two competing traits are present. • Recessive: • Trait within an organism that is present, but is not expressed. • Examples: Eye color, skin tone, and cleft pallet • Genotype: • Underlying combination of genetic material present. • Not physically visible • Phenotype: • Observable trait • The trait that is actually seen.

Genetics • Homozygous: • Inheriting from parents similar genes for a given trait. • Heterozygous: • Inheriting from parents different forms of a gene for a given trait. • Polygenic inheritance: • Inheritance in which combination of multiple gene pairs is responsible for the production of a particular trait. • X-linked genes: • Genes that are considered recessive and located only on the x chromosome.

Human Genome Project Reached in 2001: • When molecular biologists succeeded in mapping the specific sequence of genes on each chromosome. • Most important moment in the history of genetics. • Discovered that 99.9% of the gene sequence is shared by all humans. • Behavioral Genetics: Studies the effects of heredity on behavior and psychological characteristics

Inherited Diseases • Down Syndrome: • Disorder produced by the presence. of an extra chromosome on the 21st pair. • Most frequent cause of mental retardation. • Fragile X Syndrome: • Produced by injury to a gene on the X chromosome. • Producing mild to moderate mental retardation.

Inherited Diseases Sickle-cell Anemia: • Blood disorder • Gets its name from the shape of the red blood cells. • Symptoms: Poor appetite, stunted growth, swollen stomach, and yellowish eyes. • Most sever form of the disease rarely live beyond childhood. • Affects one African-American in 400.

Inherited Diseases Tay - Sachs Disease: • Produces blindness and muscle degeneration prior to death • No treatment. • Usually causes death before its victims reach school age. Klinefelter’s Syndrome: • Presence of an extra x chromosome. • Produces underdeveloped genitals, extreme height, and enlarged breasts.

Inherited Diseases Genetic Counseling: • Discipline that focuses on helping people deal with issues relating to inherited disorders.

Prenatal Testing Ultrasound Sonography: • High-frequency sound waves scan the mother’s womb to produce an image of the unborn baby. • Size and shape can be addressed. Chorionic villus sampling: (CVS) • Finds genetic defects. • Involves taking samples of hair like material that surrounds the embryo.

Prenatal Testing Amniocentesis: • Identifies genetic defects • Examines a small sample of fetal cells drawn by a needle. • Inserted into the amniotic fluid surrounding the unborn fetus. • 15-20 weeks into pregnancy. • Nearly 100 percent accurate. Fetal Blood sampling: (FBS) • After 18 weeks of pregnancy. • Collects a small amount of blood from the umbilical cord. • Detects Down syndrome and most other chromosome abnormalities.

Neonates Labor: The Process of Birth Begins • Oxytocin: • Released by the mother’s pituitary gland. • When the concentration of oxytocin is high enough, mother’s uterus begins periodic contractions. • Braxton-Hicks Contractions: (After 4th month) • False labor • Contractions will eventually get strong enough to force the fetus down the birth canal until the baby enters the world. • Cone-head (Don’t Panic!)

Neonates:The Stages of Labor Most labors take 16-24 hours for firstborn children. • Duration of labor can vary depending on mother’s: • Age • Race • Ethnicity • Number of prior pregnancies

Neonates:The Stages of Labor Stage 1: (Longest stage) • Uterine contractions every 8-10 minutes • Last 30 seconds • Toward the end contractions occur every 2 minutes • Last 2 minutes • As the contractions increase the cervix (separates uterus from the vagina) becomes wider • Eventually expanding to allow the baby’s head to pass through • Transition: Final part of the first stage • Fully opened cervix is usually around 10cm Stage 2: (Approx. 90 min) • Episiotomy: Incision made to increase the size of the vagina to help in stretching • Is it ethical? • Baby’s head emerges from the mother • Stage ends when the baby has completely left the mother • The placenta is still inside the mother at the end of this stage

Neonates:The Stages of Labor Stage 3: (Quickest stage) • Expelling of the umbilical cord and placenta • Lasts just a few minutes • In most cases once a baby makes it outside they spontaneously cry, which helps them to clear their lungs of fluid • If they don’t the child may need to be stimulated or startled to make it cry • If it still does not: • Immediate life saving attention may be necessary

Neonates:Apgar Scale Rhythm: • Repetitive, cyclical pattern of behavior. • Important way that behavior can become integrated in the neuronal system and aide in the learning • Circadian Rhythm State: • Degree of awareness that an infant displays to both internal and external stimulation. • Alertness, fussing, crying, and different levels of sleep. • How much stimulation is necessary for a reaction

Neonates:Apgar Scale Apgar Scale Defined: A standard measurement system that looks for a variety of indications of good health in newborns. • Evaluates 5 basic qualities: • Appearance (color) • Pulse (heart rate) • Grimace (reflex irritability) • Activity(muscle tone) • Respiration (respiratory effort) Scoring: • From 0-2 on each of the five qualities • Score total ranges from 0-10 • Prognosis: • Score from 10 down to 8 means that the child is fine • Score from 7 down to 4 will most probably need help to start breathing • Score less than 4 means that the child needs immediate life-saving attention

The Apgar Scale

Neonates:If the Child does not Pass the Apgar Scale Average infant weights: 7 ½ pounds • Infant Mortality: Death within the first year of life • Anoxia: Lack of oxygen • If lasts longer than a few minutes can cause mental retardation • Stillbirth: Delivery of a child who is not alive • Less than 1 in 100

Neonates:If the Child does not Pass the Apgar Scale BIRTH COMPLICATIONS: • Preterm infants: (Premature infants) Born prior to 38 weeks after conception • High risk for illness and death. • Average preterm weighs less than 5 ½ pounds • Called Low-Birthweight Infants • High risk for infection and RDS (Respiratory Distress Syndrome) because of their lungs have not developed completely • Presents great difficulty in taking in sufficient levels of oxygen • Small-For-Gestational-Age Infants: • Due to delayed fetal growth: • Weigh 90% of the average weight of infants of the same gestational age

Neonates:If the Child does not Pass the Apgar Scale • Very-Low-Birthweight Infants: • Weigh less than 2 ¼ pounds • Been in womb less than 30 weeks • Their eyes are fused shut, and earlobes are hardly formed • Their skin is darkened red color • These infants rarely reach the Age of Viability: • Point at which an infant can survive prematurely • An infant born earlier than 25 weeks has less than a 50-50 chance of survival. • Postmature Infants: Still not born after two weeks after the mother’s due date • Blood supply from placenta may become insufficient • Blood supply to the brain may be decreased (brain damage) • Baby may be too large to make it through the birth canal

Neonates:If the Child does not Pass the Apgar Scale • Possible consequences of low birthweight: • Brain injuries • Lung and liver diseases • Learning disabilities • ADHD • Lower levels in reading and math achievement • Deficits are evident in adulthood

Neonates:If the Child does not Pass the Apgar Scale • About 50% of low-birthweight children are enrolled in special education programs. • Low birthweight is linked to asthma. • Some defects can be improved with: • Early speech therapy • Intensive enrichment programs • Kangaroo care and massage therapy

Postpartum Period • Lasts about 6 weeks after childbirth when woman adjusts physically and psychologically back to the prepregnant state. • Influenced by preceding conditions and experiences • Mother learns to care for the baby, feel good about herself and those close to her • Physical: hormone changes, weight loss, return to menstruation, loss of energy or fatigue • Psychological: feelings of depression, anxiety, coping in new role, excessive worrying

70% 20% 10% Percentage of U.S. Women Who Experience Postpartum Blues and Postpartum Depression Postpartum blues: symptoms appear 2 to 3 days after delivery and subside within 2 to 3 weeks No symptoms Postpartum depression: symptoms linger for weeks or months and interfere with daily functioning

Prenatal Development