chapter 3: prenatal development and birth ©2009 the mcgraw-hill companies, inc. all rights...

CHAPTER 3: PRENATAL DEVELOPMENT AND BIRTH

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

Life-Span DevelopmentTwelfth Edition

Prenatal Development


Conception occurs when a single sperm cell from the male unites with an ovum (egg)

Prenatal development is divided into 3 periods and lasts approximately 266-280 days:

Germinal period: first 2 weeks after conception, zygote created

Embryonic period: occurs from 2 to 8 weeks after conception

Fetal period: begins 2 months after conception and lasts until birth



Germinal Period: period of development that takes place the first two weeks after conception Rapid cell division by the zygote Blastocyst: group of cells after about 1 week Trophoblast: outer layer of cells that later provides

nutrition and support for the embryo Implantation: attachment of the zygote to the uterine

wall; occurs 10 to 14 days after conception



Embryonic Period: development from 2 to 8 weeks after conception Begins when blastocyst attaches to uterine wall Mass of cells is now called an embryo Three layers of cells: endoderm, mesoderm, and ectoderm Amnion: a bag that contains a clear fluid (amniotic fluid)

in which the embryo floats Umbilical Cord: connects the baby to the placenta Placenta: group of tissues containing mother and baby’s

intertwined blood vessels Organogenesis: process of organ formation during the first

two months of prenatal development



Fetal Period: development from two months after conception to birth Rapid growth and change Viability: the age at which a fetus has a chance of

surviving outside the womb Currently 24 weeks; changes with advances in medical

technology



The Brain: Babies have approximately 100 billion neurons (nerve

cells) at birth Architecture of the brain takes shape during the first two

trimesters Increases in connectivity and functioning occur from the

third trimester to 2 years of age Neural tube develops 18 to 24 days after conception

Anencephaly Spina bifida



The Brain: Neurogenesis: the generation of new neurons

Begins at fifth prenatal week and continues throughout prenatal period

Neuronal migration: cells move outward from their point of origin to their appropriate locations Occurs approximately 6 to 24 weeks after conception

Hazards to Prenatal Development


Teratogen: any agent that can cause a birth defect or negatively alter cognitive and behavioral outcomes Drugs (prescription, nonprescription) Incompatible blood types Environmental pollutants Infectious diseases Nutritional deficiencies Maternal stress Advanced age of parent



Severity of damage to the unborn depends on: Dose Genetic susceptibility Time of exposure

Critical period: a fixed time period during which certain experiences or events can have a long-lasting effect on development



Prescription and Non-prescription Drugs: Many women are given drugs while pregnant

Some are safe; some can cause devastating birth defects Known prescription teratogens include antibiotics,

some antidepressants, some hormones, and Accutane Non-prescription teratogens include aspirin and diet

pills



Psychoactive Drugs: drugs that act on the nervous system to alter states of consciousness, modify perceptions, and change moods Includes caffeine, alcohol, nicotine

Caffeine: small risk of miscarriage and low birth weight for those

consuming more than 150 mg. daily Increased risk of fetal death for those consuming more

than 300 mg. daily FDA recommends not consuming caffeine or consuming it

sparingly



Alcohol: Fetal alcohol syndrome: abnormalities in newborn due to

mother’s heavy use of alcohol in pregnancy Facial deformities Defective limbs, face, heart Most have below-average intelligence; some are mentally retarded

Even light to moderate drinking during pregnancy has been associated with negative effects on the fetus

FDA recommends no alcohol consumption during pregnancy



Nicotine: Maternal smoking can negatively influence prenatal

development, birth, and postnatal development Associated with:

Preterm births and low birth weight Fetal and neonatal death Respiratory problems SIDS (sudden infant death syndrome) ADHD (attention deficit hyperactivity disorder)



Illegal drugs that harm during pregnancy: Cocaine Methamphetamine Marijuana Heroin

Incompatible blood types (Rh factor) Can cause mother’s immune system to produce

antibodies that will attack the fetus



Environmental hazards: Radiation Environmental pollutants and toxic wastes

Maternal Diseases: Sexually transmitted diseases (syphilis, genital herpes,

AIDS) Rubella Diabetes



Maternal factors:Maternal diet and nutritionMaternal ageEmotional states and stress

Paternal factors: Exposure to teratogens Paternal age

Prenatal Care


Prenatal care typically includes: Screening for manageable conditions and treatable

diseases Medical care Educational, social, and nutritional services

Centering Pregnancy: relationship-centered program

Importance of prenatal care


20

0

30

40

50

60

70

80

90

100

10

20041990

Percentage

Non-Latino White women

African American

womenLatino women

Percentage of U.S. Women Using Timely Prenatal Care: 1990 to 2004

The Birth Process


Three stages of birth: Stage 1: uterine contractions begin at 15 to 20 minutes

apart and last up to 1 minute, becoming closer and more intense with time Causes the cervix to stretch and open to about 10 cm This stage lasts an average of 12 to 14 hours

Stage 2: baby’s head begins to move through dilated cervix opening and eventually emerges from the mother’s body This stage lasts approximately 45 minutes

Stage 3: umbilical cord, placenta, and other membranes are detached and expelled (afterbirth)

The Birth Process


Childbirth Setting and Attendants: 99% of deliveries take place in hospitals Home delivery or freestanding birth center Compared to doctors, midwives:

Typically spend more time than doctors counseling and educating patients

Provide more emotional support Are typically present during the entire labor and delivery process

Doulas provide continuous physical, emotional, and educational support for mother before, during, and after childbirth

Methods of Childbirth


Key choices involve use of medication and when to have a cesarean delivery

Typical pain medication: Analgesia: pain relief Anesthesia: blocks sensation in an area of the body

(can also block consciousness) Epidural block

Oxytocics: synthetic hormones used to stimulate contractions



Natural childbirth: aims to reduce pain by decreasing fear and using breathing/relaxation techniques

Prepared childbirth (Lamaze): special breathing techniques; education about anatomy and physiology Basic belief is that, when information and support are

provided, women know how to give birth



Other natural techniques used to reduce pain: Waterbirth: giving birth in a tub of warm water Massage Acupuncture: insertion of very fine needles into

specific locations in the body Hypnosis: the induction of a psychological state of

altered attention and awareness Music therapy: utilizes music to reduce stress and

manage pain



Cesarean Delivery: the baby is removed from the mother’s uterus through an incision made in the abdomen Often used if baby is in breech position or other

complications arise Cesareans involve a higher infection rate, longer hospital

stays, and a longer recovery time Rate of cesarean births has increased dramatically in

recent years Better identification of complications Increase in overweight and obese mothers Extra caution by doctors to avoid lawsuits

Transition from Fetus to Newborn


Birth process is stressful for baby Anoxia: a condition in which the fetus has an insufficient

supply of oxygen Baby secretes adrenaline and noradrenalin, hormones that

are secreted in stressful circumstancesMeasuring neonatal health and responsiveness:

Apgar Scale: assessed at 1 minute and 5 minutes after birth evaluates heart rate, body color, muscle tone, respiratory effort,

and reflex irritability 10 is highest, 3 or below indicates an emergency



Measuring neonatal health and responsiveness: Brazelton Neonatal Behavioral Assessment Scale

(NBAS): Typically performed within 24–36 hours after birth Assesses newborn’s neurological development, reflexes, and

reactions to people and objects Low scores can indicate brain damage or other difficulties

Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS): Provides a more comprehensive analysis of newborn’s behavior,

neurological and stress responses, and regulatory capacities Assesses the “at-risk” infant

Preterm and Low Birth Weight Infants


Preterm and Small-for-Date Infants: Low birth weight infants weigh less than 5 ½ lbs. at birth Preterm infants are those born three weeks or more before full

term Small-for-date infants are those whose birth weight is below

normal when the length of the pregnancy is consideredRate of preterm births has increased

Number of births to mothers 35 years and older Rates of multiple births Management of maternal and fetal conditions Substance abuse Stress



Causes of low birth weight: Poor health and nutrition Cigarette smoking Adolescent births Use of drugs Multiple births/reproductive technology Improved technology and prenatal care



Possible consequences: Language development delays Lower IQ scores Brain injury Lung or liver diseases More behavioral problems Learning disabilities ADHD Breathing problems (asthma) Approximately 50% are enrolled in special education

programs



Some effects can be improved with: Early speech therapy Intensive enrichment programs Kangaroo care, massage therapy, and breast feeding

Kangaroo Care: treatment for preterm infants that involves skin to skin contact

Massage: research conducted by Tiffany Field

The Postpartum Period


Postpartum period lasts about six weeks or until the mother’s body has completed its adjustment and has returned to a nearly pre-pregnant state

Physical Adjustments: Fatigue Hormone changes Return to menstruation Involution: process by which the uterus returns to its pre-

pregnant size 5–6 weeks after birth Weight loss/return to exercise



Emotional and Psychological Adjustments: Emotional fluctuations are common “Baby Blues” experienced by 70% of new mothers in the

U.S. Typically resolves in 1–2 weeks, without treatment

Postpartum Depression Excessive sadness, anxiety, and despair that lasts for two weeks or

longer Experienced by 10% of new mothers Hormonal changes after birth may play a role May affect mother–child interactions


Postpartum blues: symptoms appear 2 to 3 days after delivery and subside within 1 to 2 weeks

No symptoms

10%

70%

20%

Postpartum depression: symptoms linger for weeks or months and interfere with daily functioning

Percentage of U.S. Women Who Experience Postpartum Blues and Postpartum Depression



A Father’s Adjustment: Many fathers feel that the baby gets all of the

mother’s attention Parents should set aside time to be together Father’s reaction is improved if he has taken

childbirth classes and is an active participant in the baby’s care

Bonding


Bonding: the formation of a connection, especially a physical bond, between parents and the newborn in the period shortly after birth Isolation of premature babies and use of drugs in birth

process may harm bonding process Bonding may be a critical component in the child’s

development However, close contact in the first few days may not be necessary

Most hospitals offer a rooming-in arrangement while mother and child are in the hospital

chapter 3: prenatal development and birth ©2009 the mcgraw-hill companies, inc. all rights...

Documents

mcgrawhill companies

prenatal development2009

prenatal week

period of development

conception fetal period

embryonic period

germinal period

group of cells