Prenatal Development and Childbirth
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Transcript of Prenatal Development and Childbirth
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Prenatal Development and Childbirth
Chapter 3
3
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Prenatal Development and Childbirth
• Prenatal Growth and Development
• Prenatal Environmental Influences
• Childbirth
• The Evolving Family
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Prenatal Growth and Development• Prenatal development is divided into three
periods:– Germinal: 0 to 2 weeks
– Embryonic: 2 to 8 weeks
– Fetal: 9 to 38 weeks
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Prenatal Growth and Development
• Ovulation occurs about 2 weeks after start of menstrual period– The ovum (egg) travels through fallopian
tubes, where fertilization may take place
– If fertilization takes place, a zygote results
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Two Ways to Describe the Prenatal Period
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Germinal Period
• Time of extremely active cell vision
• Toward end of first week after conception, cells have developed into a blastula, ball of cells around a fluid-filled center
• Cells begin to differentiate to form supportive structures
• Twins may develop during the first few divisions of the zygote
– Monozygotic (identical) twins develop when two identical cells separate and develop into two embryos
– Dizygotic (fraternal) twins develop when two eggs (ova) are released simultaneously and each unites with a different sperm
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Ovulation and Fertilization
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Embryonic Period
• Beings when implantation is complete
• Some cells form the embryonic disc, from which the child will develop
• Other cells will form supportive structures differentiated into the: – placenta
– umbilical cord
– amniotic sac
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The Embryo
• Develops into three distinct layers:
– Ectoderm: outer layer
• Will become skin, sense organs, brain, nervous system
– Mesoderm: middle layer
• Will become muscles, blood, excretory system
– Endoderm: inner layer
• Will become digestive system, lungs, thyroid, thymus, and other organs
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The Embryo (continued)
• During the second month, most major body structures develop, except the brain
• Spontaneous abortions (miscarriages) occur primarily during first trimester, usually by 12 or 13 weeks
– Often caused by genetic defects or unsuccessful implantation
– Maternal age, health, nutrition, and exposure to toxic substances, are also risk factors
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The Fetal Period
• Lasts from the beginning of third month until birth
• Organs and systems mature and develop, especially the brain and nervous system
• At age 24 weeks, the healthy fetus reaches the age of viability, meaning it has a 50% chance of surviving outside the womb if given high-quality intensive care
• Half of surviving fetuses born at 24 weeks have serious anomalies
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Milestones of Development in the Fetal Period
• Week 12– Size: 3 inches long, 1 ounce– Arms, legs, and fingers are developed and can
move– Fingerprints developed– Sexual organs developed– Vocal cords and taste buds formed– Eyes and teeth begin to develop
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Milestones of Development in the Fetal Period
• Week 16– Size: 5 1/2 inches long, 4 ounces– Heartbeat is stronger and more regular– Lanugo develops and covers the body– Fingernails and toenails developed
• Week 20– Size: 10-12 inches long, 8 oz. – 1 pound– Senses of taste and smell formed– Hair and eyelashes developed– Movements can be detected by mother– Fetus sucks its thumb
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Milestones of Development in the Fetal Period
• Week 24 (age of viability)– Size: 11-14 inches long, 1 pound to 1 pound 8 oz.– Eyes formed and open– Posture straightened and internal organs shift– Brain development occurs
• Week 28– Size: 14-17 inches long, 2 pounds, 8 oz. to 3 pounds– Body fat is accumulated– Body rhythms developing– Brain develops localized centers– Fetus can feel pain and touch; responds to sound and vibration
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Milestones of Development in the Fetal Period
• Week 32– Size: 16 ½ - 18 inches long, 4-5 pounds– Rapid weight gain; body regulation becomes refined– Most bones formed– Fetus could survive without medical intervention
• Week 36-38– Size: 19 inches long, 6 pounds– Hearing is complete– Fetus shifts to “head-down”– Vernix caseosa falls away; lanugo dissolves– Antibodies are passed from the mother
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Developmental Trends
• Three general trends characterize early developmental processes:– Cephalocaudal trend
• Development advances from the head to the feet
– Proximodistal trend• Development proceeds from the middle of the
body outward
– Gross-to-specific trend• Responses become more specific as development
advances
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Developmental Trends• Three general trends characterize early
developmental processes:– Cephalocaudal trend
• Development advances from the head to the feet
– Proximodistal trend• Development proceeds from the middle of the
body outward
– Gross-to-specific trend• Responses become more specific as development
advances
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Prenatal Environmental Influences
• Both genetic defects and environmental influences during the prenatal period or childbirth can result in congenital anomalies
• Maternal age is linked to increased incidence of congenital anomalies
– One in 25 mothers over the age of 45 will have a child with Down syndrome
– Age may be related to age of the ova, which may become damaged over time
– Hormone levels also shift as women age
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Maternal Health and Nutrition
• Maternal malnutrition in pregnancy is linked to:– higher rates of spontaneous abortion
– premature birth
– stillbirth
– later difficulties in development
• Early quality prenatal care is associated with having healthy babies
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Critical Periods in Prenatal Development
• A critical period is one during which the developing child is at the greatest risk for harm as a result of teratogens
• Sometimes exposure to a specific teratogen causes specific harm
• Or, exposure to certain teratogens may increase overall risk of damage
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Critical Periods in Prenatal Development
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Teratogens and Their Effects
• Viruses (HIV, rubella, the flu) may cross the placental barrier and affect the baby
• Using HAART therapy and Caesarian delivery, mother-to infant HIV transmission reduced to near zero
• Certain prescription drugs can cause damage
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Teratogens and Their Effects
• Prenatal alcohol exposure: – May cause fetal alcohol affects or fetal alcohol
syndrome
– Also increases risk for learning disabilities, attention problems, and hyperactivity
– No amount of alcohol consumption during pregnancy is safe
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Video Clip
Facts about fetal alcohol syndrome and faces of victims:http://www.youtube.com/watch?v=04IlEeh9vPs
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Teratogens and Their Effects
• Marijuana exposure is linked to birth defects, structural defects, and cognitive deficiencies
• Cigarette smoking may lead to stillbirth, prematurity, spontaneous abortion, low birth weight and cognitive deficits
• Amphetamine drugs (e.g., cocaine) may damage the nervous system
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Childbirth• Three stages:
– initial labor
– labor and delivery
– afterbirth
• Childbirth practices vary widely among cultures and generations
• Many women prefer natural childbirth today, though with medical assistance
• Birthing centers are becoming more common• Cesarean section used in 26% of U.S. births
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Technological Innovations
• Allow physicians to detect problems early in pregnancy:
– Chorionic villus sampling (CVS)
– Ultrasound
– Amniocentesis
– Fetal monitors
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Video Clip
Broadcast news story on 3D and 4D ultrasound technology:http://www.youtube.com/watch?v=ERTgbRnlAQw
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Complications in Childbirth
• Breech presentation may require c-section
• Baby’s general health is evaluated on the 10-point Apgar Scale
• Prematurity is associated with:
– Low birth weight
– Difficulty adjusting after birth
– Behavioral problems in childhood
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Video Clip
Describes the benefits of kangaroo care:http://www.youtube.com/watch?v=8hLo4_4ksAI
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The Apgar Scoring System for Newborns
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Video Clip
Description of the Apgar scale: http://www.youtube.com/watch?v=3C6F74Zs1BE
Copyright © 2010 Pearson Education, Inc. All rights reserved.
The Evolving Family• Birth is a psychological and social milestone for
the family
• The transition to parenting can be challenging– Pregnancy affects mothers emotionally and
psychologically, as well as physically
– Fathers may feel a greater sense of responsibility and concern about the future
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Video Clip
Describes a nurse-family partnership program in Sacramento County, California that is in danger of being eliminated:http://www.youtube.com/watch?v=PwdiEtExyMg
Copyright © 2010 Pearson Education, Inc. All rights reserved.
The Newborn• The child experiences birth trauma
• Average full-term newborn weighs between 5 pounds, 8 ounces and 9 pounds, 8 ounces
• Typically between 19 and 22 inches long
• May have enlarged genitalia
• Upon birth, babies make major adjustments to their respiration, circulation, digestion, and temperature regulation
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The Newborn
• Babies are born with two types of reflexes
– Survival
• Breathing, sucking, rooting, sneezing, gagging
– Primitive
• May have had survival value in evolutionary past, these reflexes disappear during first months of life
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Video Clip
Description of the primary reflexes:http://www.youtube.com/watch?v=gyVLD0hl0XY
Copyright © 2010 Pearson Education, Inc. All rights reserved.
The Newborn
• Social and emotional processes of the infant will lead to development of attachment
• Attachment is reciprocal:
– Extends from infant to caregiver and visa versa
– For example, breast-feeding is good for mother and baby
• Infant-caregiver interactions shortly after birth establish the foundation of the attachment relationships that will continue through life
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Summary
• Prenatal development is divided into three 3-month trimesters—germinal, embryonic, and fetal
• Three general trends characterize early development—cephalocaudal, proximodistal, and gross-to-specific
• Genetic defects and environmental influences (e.g., maternal age, malnutrition, and specific teratogens) can cause birth defects
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Summary
• Childbirth is divided into three stages—initial labor, labor and delivery, and afterbirth
• Childbirth customs vary across cultures
• Cesarean sections are being increasingly performed, even when not medically necessary
• Premature is associated with low birth weight and early adjustment difficulties
• A baby’s general health can be evaluated on a scale called the Apgar Scoring System
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Summary
• Birth marks a dramatic transition for newborns, who must make major adjustments to their respiration, circulation, digestion, and temperature regulations
• Babies are born with survival reflexes• Shortly after birth, babies and caregivers
engage in behaviors that will lead to attachment
• Attachment forms the foundation for later social and personality development