prenatal development and birth chapter 4. periods of prenatal development the period of the zygote...
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Prenatal Prenatal Development and Development and
BirthBirth
Chapter 4Chapter 4
Periods of Prenatal Periods of Prenatal DevelopmentDevelopment
The Period of The Period of the Zygotethe Zygote– Zygote Zygote
blastocystblastocyst– Cell Cell
differentiatiodifferentiationn
– % of % of blastocysts blastocysts that fail to that fail to implant?implant?
Periods of Prenatal Periods of Prenatal DevelopmentDevelopment
The Period of the Zygote (con’t)The Period of the Zygote (con’t)– Outer layer of blastocyst develops into:Outer layer of blastocyst develops into:
AmnionAmnion ChorionChorion PlacentaPlacenta Umbilical cordUmbilical cord
**note that these structures actually develop **note that these structures actually develop during the period of the embryoduring the period of the embryo
Periods of Prenatal Periods of Prenatal DevelopmentDevelopment
The Period of the EmbryoThe Period of the Embryo– From implantation (week 3) to week 8From implantation (week 3) to week 8– Embryonic disk is already differentiating Embryonic disk is already differentiating
into:into: EctodermEctoderm (nervous system, skin, hair, sensory (nervous system, skin, hair, sensory
receptorsreceptors MesodermMesoderm (muscles, bones, circulatory (muscles, bones, circulatory
system, reproductive system, excretory system, reproductive system, excretory system)system)
EndodermEndoderm (digestive system, lungs, urinary (digestive system, lungs, urinary tract, other internal organs)tract, other internal organs)
Periods of Prenatal Periods of Prenatal DevelopmentDevelopment
The Period of the Embryo (con’t)The Period of the Embryo (con’t)– By 4By 4thth week, heart has formed and week, heart has formed and
begun to beatbegun to beat– Becomes more human in appearance Becomes more human in appearance
during 2during 2ndnd month month– Sexual differentiation during 7Sexual differentiation during 7thth – 8 – 8thth
weeksweeks
Periods of Prenatal Periods of Prenatal DevelopmentDevelopment
The Period of the FetusThe Period of the Fetus– Final 7 months of pregnancyFinal 7 months of pregnancy– FetusFetus– Digestive and excretory systems Digestive and excretory systems
functionalfunctional– Sex detected by ultrasound by end of 3Sex detected by ultrasound by end of 3rdrd
monthmonth– Kicks and movements strong enough to Kicks and movements strong enough to
be feltbe felt– Organ systems mature rapidly during Organ systems mature rapidly during
final 3 monthsfinal 3 months
Periods of Prenatal Periods of Prenatal DevelopmentDevelopment
The Period of the Fetus (con’t)The Period of the Fetus (con’t)– Viable between 22-28 weeksViable between 22-28 weeks– Receives antibodiesReceives antibodies– Assume upside-down position in final Assume upside-down position in final
weeksweeks Weight of headWeight of head Shape of uterusShape of uterus
Trends in DevelopmentTrends in Development
Cephalocaudal TrendCephalocaudal Trend
Proximodistal TrendProximodistal Trend
TeratogensTeratogens
Root word means “formation of Root word means “formation of monsters”monsters”
Harm isn’t always simple or Harm isn’t always simple or straightforwardstraightforward
Amount and length of exposureAmount and length of exposure Genetic makeup of mother/babyGenetic makeup of mother/baby Presence of several negative factorsPresence of several negative factors
TeratogensTeratogens
Same defect Same defect different teratogens different teratogens One teratogen One teratogen different defects different defects Some effects seen laterSome effects seen later
TeratogensTeratogens
Age of babyAge of baby Sensitive periodSensitive period
TeratogensTeratogens
Paternal influences often overlookedPaternal influences often overlooked– Direct and indirect effectsDirect and indirect effects– Second hand smokeSecond hand smoke– ChemicalsChemicals– Cocaine can “hitchhike”Cocaine can “hitchhike”– Smoking, alcohol, drug use Smoking, alcohol, drug use sperm sperm– Diets low in vitamin CDiets low in vitamin C
Other FactorsOther Factors
ExerciseExercise NutritionNutrition Emotional stressEmotional stress Rh blood incompatibilityRh blood incompatibility Maternal/Paternal ageMaternal/Paternal age
– Older Older less fertile, more risk of disorders less fertile, more risk of disorders– Younger Younger increased risk of prematurity, increased risk of prematurity,
infant deathinfant death
Other FactorsOther Factors
Infectious DiseasesInfectious Diseases Prenatal CarePrenatal Care Previous birthsPrevious births
Perinatal EnvironmentPerinatal Environment
Environment surrounding birthEnvironment surrounding birth Stages of childbirthStages of childbirth
– ContractionsContractions– DeliveryDelivery– AfterbirthAfterbirth
Newborn appearanceNewborn appearance
Perinatal EnvironmentPerinatal Environment
Assessing the NewbornAssessing the Newborn– Apgar scaleApgar scale– 1 minute and 5 minutes after birth1 minute and 5 minutes after birth
Perinatal EnvironmentPerinatal Environment
Assessing the NewbornAssessing the Newborn– Neonatal Behavioral Assessment Scale Neonatal Behavioral Assessment Scale
(NBAS)(NBAS) Several days after birthSeveral days after birth 20 inborn reflexes20 inborn reflexes Reactions to comforting and social stimuliReactions to comforting and social stimuli Unresponsiveness may indicate neurological Unresponsiveness may indicate neurological
problemsproblems Can be a parent teaching toolCan be a parent teaching tool
Perinatal EnvironmentPerinatal Environment
ComplicationsComplications– AnoxiaAnoxia
Severe Severe cerebral palsy, mental retardation cerebral palsy, mental retardation Mild Mild irritability, motor/cognitive delays irritability, motor/cognitive delays Chances have been reduced with fetal Chances have been reduced with fetal
monitoringmonitoring Respiratory distress syndromeRespiratory distress syndrome
– Complicated deliveryComplicated delivery ForcepsForceps Cesarean Cesarean Medications Medications
Preterm and Small-for-DatePreterm and Small-for-Date
Preterm = born more than 3 weeks Preterm = born more than 3 weeks early, but appropriate weight for time early, but appropriate weight for time in wombin womb
Small-for-Date = underweight due to Small-for-Date = underweight due to slow fetal growthslow fetal growth– Greater risk than pretermGreater risk than preterm– Causes include smoking, drug use, Causes include smoking, drug use,
stress, lack of prenatal care, multiple stress, lack of prenatal care, multiple births, social supportbirths, social support
Postterm = born after 42 weeksPostterm = born after 42 weeks