Chapters 2 and 3 life span development

Life Span DevelopmentSpring 2010Prenatal Development – Chapter 2Birth and the Newborn Infant – Chapter 3

The Code of LifeHumans begin life as a single cell.Our genetic code is stored and communicated in

our Genes – the basic units of genetic informationGenes are composed of sequences of DNA

(deoxyriboneucleic acid). Our DNA determines the nature of every cell in the body and how it will function.

Humans have over 25,000 genesOur genes are arranged in a specific order along

46 chromosomes (23 pairs). A chromosome is a very long DNA molecule and associated proteins that carry portions of the hereditary information of an organism.

Cells, Chromosomes, and DNA

Influence of Heredity on DevelopmentCell Division: Mitosis and Meiosis Mitosis

◦ Genetic code carried into new cells◦ Each chromosome splits and combines with chemicals to retake it’s

original

form, resulting in 2 identical copies of DNA Meiosis

◦ Process which forms games (sperm and ova), which have only 23 chromosomes

◦ Each pair of chromosomes split, one member of each moving into a new cell

Fertilization◦ Sperm and ovum cells provide 23 chromosomes each, to form 23 pairs◦ 22 are autosomes◦ 23rd pair are sex chromosomes

X or Y chromosomes determine sex of child XX: female; XY: male

Mitosis

Multiple BirthsMonozygotic (MZ) Identical Twins

◦ Derive from a single zygote, which splits it two and develops into two individuals

with the same genetic code.◦ Rarer than DZ twins

Dizygotic (DZ) Fraternal Twins◦ Derive from two separate fertilized ova.◦ Family background

Chances of Bearing Twins◦ Later in life◦ Fertility Drugs

Dominant and Recessive Traits

How do genes determine traits?◦ Traits are determined by pairs of genes; consisting of two

alleles Homozygous: two identical alleles Heterozygous: two different alleles

Law of Dominance (Gregor Mendel)◦ When a dominant allele is paired with a recessive allele, the

dominant will determine trait expressed in the offspring 1 brown eyed allele and 1 blue eyed allele = brown eyed trait

◦ Recessive traits will be expressed only when two recessive alleles are paired 1 blue eyed allele and 1 blue eyed allele = blue eyed trait

◦ Carrier Person who carries & transmits recessive genes but doesn’t

exhibit them

Chromosomal AbnormalitiesChromosomal Abnormalities (More or less than 46

chromosomes) Down Syndrome

◦ Extra chromosome on 21st pair; resulting in 47 chromosomes◦ Facial feature abnormalities; cardiovascular problems; cognitive,

language, and

motor development impairments.

Sex Linked Chromosomal Abnormalities XYY Syndrome (Males with extra Y chromosome)

◦ Heightens secondary sex characteristics Klinefelter’s Syndrome (Males with extra X chromosome)

◦ Less testosterone; sex characteristic abnormalities; gynecomastia; infertility

Turner Syndrome (Females with missing X chromosome)◦ Lack estrogen; infertility; hindered development of ovaries and breasts.

Triple X Syndrome (Females with extra X chromosome)◦ Normal appearance; some cognitive deficiency; increased rate of

infertility.

Genetic Abnormalities Phenylketonuria (PKU)

◦ Failure to metabolize amino acid phenylalanine causes CNS impairments.

◦ Cause of mental retardation Huntington’s Disease

◦ Fatal, progressive degenerative disorder; uncontrollable muscle movements

Sickle-Cell Anemia◦ Red blood cells are malformed and obstruct blood vessels.◦ Can cause swollen joints, stroke, heart attack and kidney failure

Cystic Fibrosis◦ Most common fatal hereditary disease among European Americans◦ Excessive production of thick mucus that clogs pancreas and

lungs.

Sex-Linked Genetic Abnormalities Hemophilia

◦ Disorder in which blood does not clot properly◦ Carried by the X chromosome

Genetic Counseling and Prenatal Testing Genetic Counseling

◦ Advice concerning the probability that children will show genetic abnormalities

Prenatal Testing◦ Amniocentesis

Need withdraws fetal cells from amniotic sac and examines them for genetic and chromosomal abnormalities

◦ Chorionic Villus Sampling (CVS) Syringe extracts villa from outer membrane of amniotic sac via

vagina◦ Ultrasound

High frequency sound waves provide picture of the fetus Identify fetal position, multiple pregnancies, sex, growth, and

structural abnormalities◦ Blood Tests

Can identify presence of recessive genes for a variety of disorders Alpha-fetoprotein Assay (AFP) blood tests

Conception Conception

◦ Union of sperm cell and ovum that occurs when chromosomes of each of these cells combine to form 23 new pairs

◦ Gametes fuse and form the zygote. ◦ Beginning of new human life

The Ova◦ Women have 400,000 ova at birth, which development via

hormones◦ At puberty, ova begin to mature and each month are released◦ Enter fallopian tube and if not fertilized, are discharged with

endometrium The Sperm Cells

◦ Sperm cells can contain X or Y sex chromosomes (Y swim faster)◦ About 200 to 400 million sperm in each ejaculation; each of

which has the possibility of fertilizing the ovum.

Conception The Journey to Conception

◦ Only 1 / 1000 sperm will ever arrive at the vicinity of the ovum

◦ Those that survive, reach fallopian tubes 60 – 90 minutes after ejaculation

◦ Some enter the wrong tube, others fail to make the final 2 inch journey

◦ Travel is not random – chemical secreted by ovum attracts sperm

Fertilization◦ Only one sperm will be able to fertilize the ovum◦ Ova are surrounded by a layer called the zona pellucida◦ Sperm secretes hyaluronidase, which opens the layer

enabling penetration◦ Once a sperm has entered, layer hardens◦ Chromosomes for sperm and ovum line up to create 23

new pairs with a unique set of genetic instructions.

Female Reproductive Organs

Infertility15% of couples suffer from infertility – the

inability to conceive after 12-18 months of trying to become pregnant

Infertility can be caused by a variety of factors:◦ The age of the parents◦ Previous use of birth control, illicit drugs,

cigarettes, STDs◦ Abnormally low sperm count in men◦ The woman’s mother taking certain drugs

during pregnancy◦ Failure of the ovaries to release an egg – this

can be caused by hormonal imbalance in the woman, damage to the fallopian tubes or uterus, or stress

Causes of Infertility In men:

◦ Low sperm count – most common problem◦ Deformed sperm◦ Low sperm motility

Extensive athletic activity◦ Infectious disease◦ Direct trauma to testes

In women:◦ Irregular ovulation or failure to ovulate – most common problem

Hormone irregularity, stress, malnutrition◦ Various infections◦ Inflammation of tissue

Endometriosis: inflammation of endometrial tissue that is sloughed off into the abdomen rather than out of the body during menstruation

◦ Barriers or disorders in passageways Pelvic Inflammatory Disease

Methods to Help Infertile Couples Bear Children Artificial Insemination

◦ Sperm collected and frozen and injected into uterus at time of ovulation

◦ Low sperm count and motility In-Vitro Fertilization (IVF)

◦ Ripened ova are surgically removed and placed in lab dish with sperm

◦ Fertilized eggs are injected into others for implantation in the uterus

◦ Low sperm motility and blocked fallopian tubes Donor IVF

◦ Ovum harvested from another woman and implanted in mother◦ Low or no ova production

Surrogate Mothers◦ Artificially inseminated with fathers sperm◦ Mothers ova may be implanted

Adoption

Pre-natal DevelopmentThe Germinal StageThe Embryonic StageThe Fetal Stage

Stage 1: The Germinal Stage Germinal Stage of Pre-Natal Development

◦ From conception to implantation (0 to 2 weeks) What happens during the germinal stage?

◦ Cell division occurs◦ Within 3 – 4 days, the zygote reaches the uterus◦ After 1 week, the zygote begins to implant in uterine wall◦ The process of implantation takes approximately 1 week

What does the zygote look like?◦ Blastocyst: mass takes on fluid filled ball of cells; cell

differentiation Embryonic disk: Inner layers which become the

embryo and later the fetus Trophoblast: Outer layers differentiate four different

membranes Blood cell production, umbilical cord and placenta,

amniotic sac, chorion

Stage 2: The Embryonic Stage Embryonic Stage of Pre-Natal Development

◦ From implantation to end of the first two months (3 to 8 weeks) What happens during the embryonic stage?

◦ Most vital organ and bodily systems begin to develop from the embryonic disk Development follows the Cephalocaudal and Proximodistal trends Endoderm (outer layer): nervous system, sensory organs, hair,

outer skin Ectoderm (inner layer): digestive and respiratory systems, liver,

pancreas Mesoderm (middle layer): excretory & circularity systems, bones,

muscles Timeline of Development

◦ 3 weeks: head, blood vessels, and brain◦ 4 weeks (Embryo weights only a fraction of an ounce and is ½ inch

long) Heart begins to beat; arm and leg buds developed as well as eyes,

ears, nose, mouth; umbilical cord beings to function◦ 5 – 8 weeks (Embryo weighs 1/13 of an ounce and is one inch long)

Hands, feet, fingers, and toes develop; kidney and liver function; bones

Stage 2: continued At 5 – 6 weeks, non-descript sex organs have formed

◦ Males and females possess a pair of undifferentiated gonads and two sets of primitive duct structures (Mullerian and Wolffian)

Genetic Differentiation (7 weeks)◦ Genetic activity on the Y chromosome causes testes to

differentiate Ovaries differentiate if Y chromosome is absent

◦ At about 4 months, distinct external genital structures Effect of Hormones

◦ Androgens are necessary for the development of male sex organs Testosterone spurs differentiation of male duct system

◦ Low levels of androgen in females cause development of female sex organs Mullerian ducts develop into fallopian tubes, uterus,

and vagina

Stage 2: Embryonic Stage

Stage 3: Fetal Stage Fetal Stage of Pre-Natal Development

◦ From third month to birth (9 weeks to birth◦ Gains in size and weight and maturation of organ systems

Timeline of Development◦ 9 – 12 weeks (Fetus weighs one ounce and is 3 inches long):

Major organ systems formed; eyes distinguishable; sex of fetus can be determined visually; responds to external stimulation.

◦ End of the Second Trimester (Fetus weighs 2 lbs and is 14 inches) Mother detects fetal movement; opens and shuts eyes; sucks

thumb; sleep and wake cycle; responds to light and sound◦ End of the Third Trimester (Fetus weighs 7 lbs and is 20 inches

long) Heart and lungs increasingly able to sustain life; fatty layer

develops under skin substantial gains in height and weight; fetus turns upside down

Survival rate increases to 90% at end of the 7th month

Fetal Stage: Continued Fetal Perception

◦ End of 13th week: responds to sound waves◦ Third trimester: can determine frequencies◦ Research has found:

Memory for prenatal vocalizations Preference for mother’s voice

◦ Gains in size and weight and maturation of organ systems Fetal Movement

◦ Middle of 4th month: detect first fetal movements (squirms)◦ 29-30 weeks: vigorous kicking◦ Activity slows before birth◦ Research has found:

Individual differences Prediction of post-birth activity and motor development

Environmental Influences - Nutrition

Risks of Maternal Malnutrition◦ Can lead to low birth weight, pre-maturity, retardation of brain

development, cognitive, motor, and behavioral development problems

◦ Risks of being too slender: low birth rate◦ Risks of being too obese: stillbirth and neural tube defects

Expectant Mothers Require◦ Protein; Vitamins A – E; Iron; Zinc; Calcium; Folic Acid, &

Calories◦ Supplements often recommended

Expected Weight Gain◦ Between 25 to 35 pounds◦ ½ lb. per week during first half; 1 lb. per week during second

half◦ Sudden large gains or losses are undesirable

Environmental Issues – Drug Use Antibiotics

◦ Malformed bones; missing limbs; stillbirth; brain damage; deafness

Hormones◦ Cancer; masculinization of sex organs of female embryos

Vitamins◦ Blindness; mental retardation; hearth defects

Heroine◦ Low birth weight; pre-mature birth; toxemia◦ Infant addition and mortality◦ Behavioral, motor, and language deficits which are

apparent into childhood

Drug use - continued Marijuana

◦ Tremors, startling, premature birth; birth defects; neurological problems◦ Learning, memory, and behavioral deficits apparent into childhood◦ Predisposes offspring to opiate addition

Cocaine◦ Stillbirth; low birth weight; birth defects◦ Hyperactivity; delayed cognitive and language development; social

problems Alcohol

◦ Fetal Alcohol Syndrome: Underdeveloped brains; facial abnormalities; mental retardation; hyperactivity; learning disabilities; academic and behavioral deficits

Caffeine◦ Increased risk of miscarriage and low birth weight

Cigarettes◦ Prematurity; low birth weight; fetal death; mental retardation;

hyperactivity◦ Second hand smoke and paternal smoking also dangerous

Environmental Influences – Environmental Hazards Lead

◦ Delayed cognitive and intellectual functioning; memory deficits

◦ Paternal exposure increases incidence of kidney tumors Mercury

◦ Mental retardation; neurological damage PCB

◦ Motor and intellectual deficiencies; decreased responsiveness

Radiation◦ Damage to organs (eyes), central nervous system, and

skeleton◦ Mental retardation and physical deformities◦ Paternal exposure increases incidence of leukemia

Environmental Influences – Stress and Aging Maternal Stress

◦ Linked to secretion of hormones with pass through placenta

◦ Connected to complications during pregnancy and labor

◦ Connected to low preterm, low-birth weight, and irritable babies

Parental Age◦ Aging fathers produce abnormal sperm

◦ Ideal maternal age: 20s Teenage: high incidence of infant mortality and low

birth weight Over 30: fertility declines; increased risk of

chromosomal abnormalities and Downs Syndrome and stillborn and preterm babies

Birth and the Newborn InfantThe Process of Birth Begins…Neonates – term used for

newbornsAbout 266 days after conception,

a protein called corticotropin-releasing hormone (CRH) triggers the process of birth

The hormone oxytocin is released from the mother’s pituitary – build-up of oxytocin begins periodic contractions

Dropping or Lightening

◦ Head of fetus settles in pelvis

Braxton-Hicks contractions

◦ First uterine contractions may be experienced as early as 6th month

Blood spotting in vaginal secretions

◦ Day or so before labor

Rush of amniotic fluid from vagina

◦ Occurs in 1 woman in 10

Other Signs

◦ Indigestion, diarrhea, backache, abdominal cramps

Fetus Signals to the Mother

◦ Adrenal and pituitary glands secrete prostaglandins and oxytocin to stimulate labor contractions.

Countdown...

Stage 1

Lasts from a few hours to more than a day

Uterine contractions efface and dilate cervix

◦ Cervix must dilate 10cm (4 inches)

◦ Contractions increase in strength, frequency, and regularity

Mother may be prepped for episiotomy

Fetal monitoring

◦ Measure fetal heart rate and mother’s contractions

Transition

◦ Cervix is nearly fully dilated

◦ Head of fetus moves into vagina (birth canal)

◦ Frequent and strong contractions

The First Stage

Stage 2 Begins when baby appears at birth canal; ends with birth May last few minutes to few hours Crowning

◦ Baby’s head begins to emerge from birth canal

Episiotomy may be performed once crowning takes place◦ Used to prevent tearing of mother

◦ Controversial and used less frequently

Baby breathes on its own

◦ Once baby’s head emerges mucus is suctioned from the mouth

Umbilical cord is clamped and severed◦ Stump will fall off 7 – 10 days later

Newborn may be removed◦ Foot-printed; ID bracelet; drops are applied to eyes; Vitamin K

injection

The Second Stage

Stage 3

Also referred to as the placenta stage

Lasts minutes to an hour or more

Placenta separates from the wall of uterus and is expelled

◦ Bleeding is normal

◦ Uterus begins to shrink

Obstetrician sews episiotomy, if performed

The exact moment of birth occurs when the fetus passes through the vagina and emerges from the mother’s body

The Third Stage

Stages of Childbirth

Stages of Childbirth

Anesthesia General anesthesia

◦ Eliminates pain by inducing sleep

◦ Short and possible long term affects to baby

Local anesthetics (i.e., epidural block)◦ Deadens pain without putting mother to sleep

◦ Minor depressive effects on neonates shortly after birth

Alternative: Natural Childbirth

Prepared Childbirth Lamaze Method

◦ Breathing techniques and relaxation training to conserve energy, relax, and lessen pain

◦ Social support and aid during labor typically provided by Lamaze coach (typically the father)

◦ Doula: experienced, nonprofessional female to provide support Fewer cesareans, less anesthesia, and shorter, less painful

labors

Methods of Childbirth

Cesarean Section Delivered by abdominal surgery Typically performed when the baby is showing signs of

distress Increase in Cesarean Sections Performed in US

◦ Mother’s small pelvis; weakness; or fatigue◦ Baby is too large; in distress (use of fetal monitors)◦ Bypass infections in birth canal from HIV or Herpes◦ Reduce malpractice suits◦ Control date / time of delivery◦ Baby in breach position or transverse position

Diversity of birthing options

LDRP All-in-one Rooms ◦ Birthing suite in hospital equipped for uncomplicated birth

Home Birth◦ Can be fairly safe for healthy women with little risk of complications

Methods of Childbirth

Oxygen Deprivation

Hypoxia - Prenatal oxygen deprivation

◦ Can impair development of central nervous system

◦ Leads to cognitive, motor, and psychological problems

Anoxia - Oxygen deprived at birth

◦ Predicted problems in learning and memory

◦ Can cause health problems such as early-onset schizophrenia

Potential Causes

◦ Maternal disorders; immaturity of respiratory system; accidents

◦ Umbilical cord squeezed during birthing process

Fetal Monitoring Technology

◦ Can detect distress to signal need for Cesarean Section

Birth Problems

Premature and/or Low Birth Weight Babies

Premature or preterm baby

◦ Occurs before 37 weeks gestation (normal is 40 weeks)

Low-birth-weight baby

◦ Weighs less than 5.5 pounds

Small for date

◦ Low-birth-weight, although born at full term

◦ More likely to remain shorter and lighter preterm babies

Risks of Low Birth Weight

◦ Babies born between 3 ¼ and 5 ½ lbs. are seven times more likely to die

◦ Poor neurological and cognitive functioning in school years

◦ Slow motor development

◦ Pre-school experience can foster cognitive and social development

Birth Problems

Postmature babies:

Postmature infants are babies who are still unborn due weeks past the mother’s due date

This is a concern for several reasons:◦ The blood supply from the placenta may

become insufficient to nourish the fetus adequately. As a result, blood supply to the brain may be decreased and could lead to brain damage

◦ Labor becomes riskier for both mom and baby, as baby is likely to be larger and needs to fit through the birth canal

◦ Doctors will typically use drugs to induce labor or perform a C-section

Maternal Depression

Depression is normal due to hormonal changes

Postpartum depression (10 – 20% mothers)◦ Begins one month after delivery and may linger for

weeks/months

◦ Major depressive disorder with PP onset

Sadness, apathy, worthlessness, changes in sleep and appetite

Interaction of physiological and psychological factors

◦ Rare form includes psychotic features

Baby may be at risk of maternal harm

◦ May profit from social support and psychotherapy

The Postpartum Period

Physical Appearance: Babies are often coated with vernix, a thick greasy substance with

smooths the passage through the birth canal Newborns are often covered with fine, dark fuzz called lanugo Newborns eyelids may be puffy and swollen from an accumulation of

liquids during birth

Bonding:Bonding is the close physical and emotional contact between a parent and child

during the period immediately following the birth. This is believed by some developmentalists to impact the long-term relationship Animal studies showed that there is a critical period just after birth when the

animals have a particular readiness to learn, or imprint, from other members of their species who are present

Lorenz demonstrated how incubator-hatched geese would imprint on the first suitable moving stimulus they saw within what he called a "critical period" between 13-16 hours shortly after hatching. Most famously, the goslings would imprint on Lorenz himself (more specifically, on his wading boots), and he is often depicted being followed by a gaggle of geese who had imprinted on him.

The Postpartum Period

Assessing Health of NeonatesNeonates – the term used for newborns. Apgar scale

◦ Based on five signs of health Appearance, Pulse, Grimace, Activity Level, Reparatory

Effort◦ Interpretation of scores

7 or above – no danger below 4 – critical condition

Brazelton Neonatal Behavioral Assessment Scale◦ Based on four areas of behaviors

Motor behavior (muscle tone & reflexes), stress response, adaptive behavior, and control over physiological state

Characteristics of Neonates: General Health

Points 0 1 2

Appearance: Color

Blue, pale Body pink; Extremities

blue

Entirely pink

Pulse:Heart Rate

Absent(not

detectable)

Slow(Below 100

beats / minute)

Rapid(100-140 beats

/ minute)

Grimace:Reflex Irritability

No response Grimace Crying, cooing, sneezing

Activity Level:Muscle Tone

Completely limp

Weak, inactive Flexed arms and legs;

resists extension

Respiratory Effort:Breathing

Absent Shallow, irregular, slow

Regular breathing;

crying

APGAR Scale

Reflexes

Unlearned responses elicited by certain types of stimulation

◦ Some have survival value, while others seem to be evolutionary

◦ Neural functioning can be determined by testing reflex

Reflexes demonstrated by neonates

◦ Rooting Reflex: turn head and mouth in direction of stroking of cheek

◦ Sucking Reflex: babies will suck object that touches the lips

◦ Moro (Startle) Reflex: back arches, legs and arms are flung out and then brought back toward chest into a hugging motion

◦ Grasping (Palmar) Reflex: babies grasp objects pressed against palms

◦ Stepping Reflex: babies will mimic walking when help upright

◦ Babinski Reflex: infant fans toes when feet are stroked

◦ Tonic-Neck Reflex: infant turns head to one side, extending arm and leg

Characteristics of Neonates: Reflexes

Rooting

Reflex

Reflexes

Vision

Visual acuity (sharpness)

◦ Estimate of 20/600

◦ Best see objects 7 to 9 inches from eyes

◦ Lack peripheral vision of older child

◦ Able to track movement within one day of birth

Visual accommodation

◦ Self-adjustments made by eye lens to bring objects into focus

◦ Neonates show little or no visual accommodation

◦ Convergence does not occur until 7 or 8 weeks

Color Vision

◦ Cones less developed than rods at birth

◦ At 3 months, can see most visible colors

Infants are not passive

Characteristics of Neonates: Sensory Capability

Hearing

Fetuses respond to sound

◦ Middle and inner ear mature in shape and size

Neonates hear remarkably well

◦ Respond to sounds of different amplitude and pitch

May play a role in attachment

◦ Show preference for mothers’ voice

◦ Pre-natal exposure to mothers voice and learning may play a role

Responsive to sounds and rhythms of speech

◦ Show no preference for specific languages

Characteristics of Neonates: Sensory Capability

Smell Well developed at birth Demonstrate facial expressions to different odors

◦ Aversion for noxious and preference for pleasant odors Recognize familiar odors

◦ Learned preference for mother

Taste Sensitive to different tastes Demonstrate facial expressions to basic tastes

◦ Discriminate between salty, sour, and bitter tastes◦ Prefer sweet tastes

Characteristics of Neonates: Sensory Capability

Touch

Sensitive to touch

◦ Touch elicits many reflex behaviors

◦ Provides comfort, security, and foundation for attachment

Pain

Less sensitive to pain than older babies

Habituation

Behavioral difference across ethic groups

◦ European American infants habituate slower than Chinese and Japanese American infants

Show a decline in interest as a repeated stimulus becomes familiar

Differences may be due to:

◦ Genetic endowment, pre-natal environment, parental behavior

Characteristics of Neonates: Sensory Capability

Neonates spend about 16 hours per day in sleep

◦ Typical infants has six cycles of waking and sleeping

Series of naps distributed throughout day and night

Sleep through the night by 6 months to 1 year

◦ Six stages of sleep and wakefulness identified

REM Sleep

◦ Brain waves similar to wakefulness; paradoxical sleep

◦ Neonates spend 50% time in REM sleep

◦ Decreases in percentage of REM

6 months – 30%

Function of REM sleep

◦ Brain activity required for brain development

◦ Older children and adults are stimulated during wakefulness

◦ Neonates compensate by spending more time in REM sleep

Characteristics of Neonates: Patterns of Sleep

Main cause of crying

◦ Pain and discomfort

Universal, expressive and functional communication

◦ Expressive response to unpleasant feelings

◦ Stimulates caregiver response

Distinct causes and patterns of cries

◦ Hunger, anger, pain

◦ Colic: sudden, loud, cries and flexing resulting from digestive tract pain

◦ Peaks of crying in late afternoon and early evening

◦ Pitch can provide information

Crying produces physiological response in others

Can be influenced by parental response

◦ Extinction

Characteristics of Neonates: Crying

Sucking serves as a built-in tranquilizer

◦ Decreases crying and agitated movements

◦ Pacifier, sweet solutions

Soothing processes

◦ Pick baby up, patting, caressing, rocking them

◦ Speaking to them in low voice

◦ Try to find cause of distress

Learning process

◦ Parents learn what works through trial and error

◦ Infants learn that crying is followed by an intervention

Is crying reinforced?

Maturation

◦ Crying tends to be replaced by less upsetting verbal requests

Characteristics of Neonates: Soothing

Sudden Infant Death Syndrome – crib death

◦ Apparently healthy babies stop breathing during sleep

◦ Most common cause of death in infants between 1 and 12 months

◦ Most likely to occur between 2 and 5 months

Period when reflexive behavior is weakening

Causes of SIDS remains obscure, but risk factors include

◦ babies aged 2 to 4 months

◦ babies put to sleep on their stomach

◦ premature and low-birth-weight babies

◦ males

◦ lower SES

◦ African Americans

◦ babies of teenage mothers

◦ babies of mothers who smoked or used narcotics during pregnancy

SIDS: Sudden Infant Death Syndrome