4—prenatal development and birth

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Slide 1

4—Prenatal Development and Birth

• Prenatal Development

• Birth

• The Postpartum Period

• Summary


Slide 2

Prenatal Development

• The Course of Prenatal Development– The Germinal Period

• The period of prenatal development that takes place in the first two weeks after conception. It includes the creation of the zygote, continued cell division, and the attachment of the zygote to the uterine wall.


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– The Germinal Period (continued)• Blastocyst: The inner mass of cells that develops

during the germinal period. These cells later develop into the embryo.

• Trophoblast: The outer layer of cells that develops in the germinal period. These cells provide nutrition and support for the embryo.

• Implantation: Attachment of the zygote to the uterine wall (10 to 14 days after conception)


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• The Course of Prenatal Development– The Embryonic Period

• The period of prenatal development that occurs 2 to 8 weeks after conception. During the embryonic period, the rate of cell differentiation intensifies, support systems for the cells form, and organs appear.

• The embryo has three layers of cells: endoderm, ectoderm, and mesoderm.


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– The Embryonic Period (continued)• Endoderm: develops into digestive and respiratory

systems.

• Ectoderm: develops into the nervous system, sensory receptors, and skin parts.

• Mesoderm: develops into the circulatory system, bones, muscles, excretory system, and reproductive system.


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– The Embryonic Period (continued)• Life-support systems develop:

– Amnion: The life-support system that is a bag or envelope containing a clear fluid in which the developing embryo floats.

– Umbilical cord: The life-support system containing two arteries and one vein; connects the baby to the placenta.

– Placenta: A disk-shaped group of tissues in which small blood vessels from the mother and offspring intertwine.


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– The Embryonic Period (continued)• Organogenesis:

– Organ formation that takes place during the first 2 months of prenatal development.


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Significant Developments in the Germinal

Period

• Refer to Figure 4.1


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The Placenta and the Umbilical Cord



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– The Fetal Period• The prenatal period of development that begins 2

months after conception and lasts for an average of 7 months.


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The Three Trimesters of Prenatal Development



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– Teratology and Hazards to Prenatal Development• Teratogen

– From the Greek word Tera, meaning “monster.” Any agent that causes a birth defect. The field of study that investigates the causes of birth defects is called teratology.

– The severity of damage and type of defect from any particular teratogen depends on dose, genetic susceptibility, and time of exposure.


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Teratogens and the Timing of Their Effects on Prenatal Development



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– Teratology and Hazards to Prenatal Development (continued)

• Prescription and Nonprescription Drugs

– Prescription drugs: Antibiotics, some antidepressants, some hormones, and Accutane.

– Nonprescription drugs: Diet pills, aspirin, and caffeine.


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• Psychoactive drugs: Act on the nervous system to alter states of consciousness, modify perceptions, and change moods.

• Alcohol: Even moderate consumption during pregnancy can result in fetal alcohol syndrome (FAS), a cluster of abnormalities such as facial deformities, defective limbs, face, and heart, below average intelligence, and mental retardation.


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• Psychoactive drugs: Nicotine– Adverse effects prenatally, perinatally, and

postnatally– Preterm births, low birth weight, fetal and

neonatal deaths, respiratory problems, and sudden infant death syndrome (SIDS)

– Possibly poor language and cognitive skills, and ADHD


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• Psychoactive drugs: Illegal drugs– Cocaine: Children are likely to develop

neurological and cognitive deficits.– Marijuana: Possible deficits in memory and

information processing..– Heroin: Newborns experience withdrawal

symptoms; later behavioral problems and attention deficits.


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• Incompatible blood types• Maternal diseases: Rubella, syphilis, genital herpes,

AIDS• Maternal diet and nutrition• Emotional states and stress• Maternal age• Paternal factors• Environmental hazards


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• Prenatal Care– Prenatal care varies enormously, but usually involves a

defined schedule of visits for medical care that includes screening for manageable conditions and treatable diseases.

– Prenatal care programs often include comprehensive educational, social, and nutritional services.


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Percentage of U.S. Women Using Timely Prenatal Care: 1990 to 2001



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• Cultural Beliefs About Pregnancy– A woman’s behavior during pregnancy is often

determined by cultural beliefs.

• Normal Prenatal Development– Most of the time, prenatal development does not go

awry and development occurs along the positive path described (Lester, 2000).


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Review and Reflect:Learning Goal 1

• Describe prenatal development– Review

• What is the course of prenatal development?

• What are some of the main hazards to prenatal development?

• What are some good prenatal care strategies?

• What are some cultural beliefs about pregnancy?

• Why is it important to take a positive approach to prenatal development?


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– Reflect• What can be done to convince women who are

pregnant not to smoke or drink? Consider the role of health-care providers, the role of insurance companies, and specific programs targeted at women who are pregnant.


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Birth

• The Birth Process– Stages of Birth

• First stage—Initially, uterine contractions are 15–20 minutes apart, last up to a minute, and cause the cervix to dilate; in the late first stage, contractions occur every 2–5 minutes and the cervix is dilated to an opening of about 4 inches.

• Second stage—Birth of the infant.

• Third stage—Delivery of the placenta (afterbirth).


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Birth

• The Birth Process (continued)– Childbirth Setting and Attendants

• While 99% of births in the U.S. take place in hospitals, births at home are more common in many other countries.

• Cultural norms differ with respect to the father’s participation in the childbirth process.


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Birth

– Childbirth Setting and Attendants (continued)

• Midwives are used by only 6% of women in the U.S. (90% of U.S. births are attended by physicians), although midwifery is the norm throughout most of the rest of the world.

• Doula: A caregiver who provides continuous physical, emotional, and educational support to the mother before, during, and just after childbirth.


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Birth

• The Birth Process (continued)– Methods of Childbirth

• Three kinds of drugs are used during labor:

– Analgesia to relieve pain

– Anesthesia to block sensation or to block consciousness

» Epidural block

– Oxytocics to stimulate contractions


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Birth– Methods of Childbirth (continued)

• Natural and Prepared Childbirth– Natural childbirth: This method attempts to reduce

the mother’s pain by decreasing her fear through education about childbirth and relaxation techniques during delivery (developed by Dick-Read).

– Prepared childbirth: This childbirth strategy is similar to natural childbirth but includes a special breathing technique to control pushing in the final stages of labor and a more detailed anatomy and physiology course (developed by Ferdinand Lamaze).


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Birth

– Methods of Childbirth (continued)• Cesarean Delivery

– Breech position: The baby’s position in the uterus that causes the buttocks to be the first part to emerge from the vagina and requires a cesarean delivery in which the baby is removed from the mother’s uterus through an incision made in her abdomen.


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Birth

• The Birth Process (continued)– The Transition from Fetus to Newborn

• During contractions, oxygen supply to the fetus is decreased

– If labor takes too long, anoxia (insufficient supply of oxygen) can develop, which can cause brain damage.

• Adrenaline and noradrenaline are secreted to protect the fetus in the event of anoxia.

• Vernix caseosa: A protective skin grease that protects the neonate against heat loss.


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Birth

• Assessing the Newborn– Apgar Scale

• A widely used method to assess the health of newborns at 1 and 5 minutes after birth. The Apgar Scale evaluates infant heart rate, respiratory effort, muscle tone, body color, and reflex irritability.

• Scale of 0, 1, or 2: Total score of 7–10 indicates good condition, 5 indicates possible problems, below 3 signals a life-threatening emergency.


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Birth

The Apgar Scale



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Birth

• Assessing the Newborn (continued)– Brazelton Neonatal Behavioral Assessment

Scale (NBAS)• A test given 24 to 36 hours after birth to assess

newborns’ neurological development, reflexes, and reactions to people; also used in research studies on infant development.

• 27 items are organized in four categories: physiological, motoric, state, and interaction.


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Birth

• Assessing the Newborn (continued)– Neonatal Intensive Care Unit Network

Neurobehavioral Scale (NNNS)• An offshoot of the NBAS to assess at-risk infants.

• Provides a more comprehensive analysis of the newborn’s behavior, neurological and stress responses, and regulatory capacities.


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Birth

• Low Birth Weight and Preterm Infants– Low birth weight: An infant who weighs less than 5 1/2

pounds at birth.

• Very low birth weight: Under 3 pounds.

• Extremely low birth weight: Under 2 pounds.

– Preterm infant: An infant born 3 weeks or more before the pregnancy has reached its full term.


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Birth

• Low Birth Weight and Preterm Infants (continued)– Small for Date Infant

• Also called a small for gestational age infant, this infant’s birth weight is below normal when the length of pregnancy is considered. A small for date infant may be preterm or full-term.


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Birth

Preterm Births in the United States: 1982–2002



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Birth

• Low Birth Weight and Preterm Infants (continued)– Incidences and Causes of Low Birth Weight

• The U.S. rate of 7.6% is considerably higher than that of many other developed countries (4–5%), but the rate in poor countries can be as high as 50%.

• Causes: Mother’s poor health and nutrition, diseases that impair fetal growth, cigarette smoking during pregnancy, young age of mother, use of drugs.


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Birth

• Low Birth Weight (continued)– Consequences of Low Birth Weight

• Most are normal and healthy.• Low brain weight increases the likelihood of brain

injury.• At-risk for lung or liver diseases.• Increased risk for learning disability, attention deficit

hyperactivity disorder, and breathing problems.• Intensive enrichment programs improve short-term

outcomes.


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Birth

• Low Birth Weight (continued)– Kangaroo Care and Massage

• Kangaroo care: A way of holding a preterm infant so that there is skin-to-skin contact that improves breathing, heart rate, temperature, sleep, and weight gain and results in decreased crying, greater alertness, and earlier hospital discharge.

• Massage: Tiffany Field has shown that massage therapy lowers stress and improves emotionality, sociability, soothability, weight gain, and earlier discharge from hospital.


Slide 41

Explorations in Child Development

Weight Gain Comparison of Premature Infants Who Were Massaged or Not Massaged



Slide 42

Review and Reflect: Learning Goal 2

• Discuss the birth process– Review

• What are the three stages of birth? What are some different childbirth strategies? What is the transition from fetus to newborn like for the infant?

• What are three measures of neonatal health and responsiveness?

• What are the outcomes for children if they are born preterm or with a low birth weight?


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– Reflect• If you are a female, which birth strategy do you

prefer? Why? If you are a male, how involved would you want to be in helping your partner through pregnancy and the birth of your baby?


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The Postpartum Period

• What Is the Postpartum Period?– The period after childbirth when the mother

adjusts, both physically and psychologically, to the process of childbirth. This period lasts for about 6 weeks or until her body has completed its adjustments and returned to a nearly prepregnant state.


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• Physical Adjustments– Initial fatigue can undermine the mother’s sense of

well-being and confidence.

– After delivery, a woman’s body undergoes sudden and dramatic changes in hormone production.

– Involution is the process by which the uterus returns to its prepregnant size 5 or 6 weeks after birth.


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• Emotional and Psychological Adjustments– “Baby Blues” and Postpartum Depression

• Signs that professional counseling is needed include:

– Excessive worrying

– Depression

– Extreme changes in appetite

– Crying spells

– Inability to sleep


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– Postpartum Depression (continued)• Postpartum depression: Strong feelings of

sadness, anxiety, or despair in new mothers that make it difficult for them to carry out daily tasks.

• The role of hormonal changes in postpartum depression has not yet been identified.

• Postpartum depression also affects the child.


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• Emotional and Psychological Adjustments– The Father’s Adjustment

• The baby comes first and gets all the attention

• Parents need to

– Set aside time for each other

– Become aware of the infant’s needs

– Develop a sensitive, comfortable relationship with the baby


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



Slide 50


• Bonding– The formation of a close connection, especially a

physical bond, between parents and their newborn in the period shortly after birth.

– Rooming-in arrangements allow the baby to remain in the mother’s room during most of the hospital stay to increase bonding.


Slide 51


• Explain the changes that take place in the postpartum period– Review

• What does the postpartum period involve? What physical adjustments does the woman’s body make in this period?

• What emotional and psychological adjustments characterize the postpartum period?

• Is bonding critical for optimal development?


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– Reflect• If you are a female, what can you do to adjust

effectively in the postpartum period? If you are a male, what can you do to help the mother adjust in the postpartum period?


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Summary

• Prenatal development is divided into three periods: germinal (conception until 10 to 14 days later), embryonic (2 to 8 weeks after conception), and fetal (2 months after conception until about 9 months, or when the infant is born).

• Teratology is the field that investigates the causes of congenital (birth) defects.


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Summary

• Prenatal care varies extensively but usually involves medical care services with a defined schedule of visits.

• Specific actions in pregnancy are often determined by cultural beliefs.

• Although things can and do go wrong during pregnancy, most of the time pregnancy and prenatal development go well.


Slide 55

Summary

• Childbirth occurs in three stages: – First: Contractions and dilation of cervix– Second: Baby’s head moves through cervix; the baby is

born– Third: Afterbirth

• Baby is prepared and capable of adapting to handle the stress of birth, but anoxia (lack of oxygen, especially if labor is prolonged) is a potential hazard.

• Childbirth strategies vary around the world.


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Summary

• For many years, the Apgar Scale has been used to assess the newborn’s health. The Brazelton Neonatal Behavioral Assessment Scale examines the newborn’s neurological development, reflexes, and reactions to people.

• More recently the Neonatal Intensive Care Unit Network Neurobehavioral Scale was created to assess at-risk infants.


Slide 57

Summary

• Low birth weight infants weigh less than 5 1/2 pounds at birth and may be preterm or small for date.

• Most low birth weight infants are normal and healthy, but as a group they have more health and developmental problem than other children.

• Kangaroo care and massage therapy are beneficial for preterm infants.


Slide 58

Summary

• The postpartum period is the name given to the period after childbirth or delivery.

• Physical adjustments in the postpartum period include fatigue, involution (the process by which the uterus returns to its prepregnant size 5 or 6 weeks after birth), hormonal changes, and deciding when to resume sexual intercourse and when to begin exercises to recover body contour and strength.


Slide 59

Summary

• Emotional fluctuation of the mother is common in the postpartum period.

• Approximately 10% of U.S. women experience postpartum depression, which involves such strong feelings of sadness, anxiety, or despair that new mothers have difficulty carrying out daily tasks.


Slide 60

Summary

• Bonding is the formation of a close connection, especially a physical bond, between parents and the newborn shortly after birth.

4—prenatal development and birth

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