2 FROM CONCEPTION TO BIRTH Phases of Prenatal DevelopmentPeriod of the zygote: conception through implantationPeriod of the embryo: 3rd-8th week, organ formation, heart beatPeriod of the fetus: 9th week-birth
3 THE PERIOD OF THE ZYGOTE Blastocyst: cellsEmbryo – inner layer of blastocystProtective/nourishing tissues – outer layerImplantation:7-10 days after conceptionTapping mother’s blood supply through uterine wallOnly 25% successfully implant
5 PERIOD OF THE ZYGOTEBlastocyst: Support StructuresAmnion: watertight sac with amniotic fluidCushioning against blowsTemperature regulationWeightless environment for movementYolk sac: early blood cell productionChorion: becomes lining of placentaAllantois: forms umbilical cord
6 Figure 4.2 The embryo and its prenatal environment.
7 PERIOD OF THE ZYGOTEPurpose of the PlacentaSemipermeableAllowing nutrients and gasses to pass throughBlood cells are too largeSite of all metabolic transactions sustaining the embryo
8 THE PERIOD OF THE EMBRYO Ectoderm (outer layer)Nervous systemSkinHairMesoderm (middle layer)MusclesBonesCirculatory system
9 THE PERIOD OF THE EMBRYO Endoderm (inner layer)Digestive systemLungsUrinary tractVital organs (pancreas, liver, etc.)
10 THE PERIOD OF THE EMBRYO Developmental Milestones3rd week – neural tube4th week – heart beat7th week – a rudimentary skeleton7th-8th weeks – sexual developmentIf male, the Y chromosome triggers a reaction to produce testes, otherwise ovaries result
12 THE PERIOD OF THE FETUSThird MonthMovement – cannot yet be felt by motherDigestive system and excretory systems functioningReproductive system contains immature ova or sperm cells
13 Figure 4. 4 Rate of body growth during the fetal period Figure 4.4 Rate of body growth during the fetal period. Increase in size is especially dramatic from the ninth to the twentieth week. ADAPTED FROM MOORE & PERSAUD, 1993.
14 THE PERIOD OF THE FETUSFourth-Sixth MonthsSucking, swallowing, breathingMovements – felt by motherHeart beat can be heard with stethoscopeSweat glands functioningVernix – protects skin from chappingLanugo – fine hair helps vernix stick to skinVisual and auditory senses are functional
15 THE PERIOD OF THE FETUSSeventh – Ninth MonthsAge of viability weeks – survival outside the womb is possibleWeight is 4 pounds (at end of 7th month)9th month – activity slows, sleep increasesBirth occurs
16 Table 4.1 Brief Overview of Prenatal Development
17 Table 4.1 Brief Overview of Prenatal Development (continued)
18 POTENTIAL PROBLEMS IN PRENATAL DEVELOPMENT Teratogen – any agent that can harm an embryo or fetusEffects of teratogensMost serious when structure is formingSusceptibility to harm is influenced by genetic makeup of mother and embryoSame defect can be caused by different teratogens
19 POTENTIAL PROBLEMS IN PRENATAL DEVELOPMENT Effects of teratogens, continuedOne teratogen can cause different defectsLonger exposure/higher dose, more harmFather’s exposure may affect embryoLong-term effects depend on postnatal environmentSome effects not apparent until later in life
20 Figure 4. 5 The critical periods of prenatal development Figure 4.5 The critical periods of prenatal development. Each organ or structure has a critical period when it is most sensitive to damage from teratogens. Dark band indicates the most sensitive periods. Light band indicates the time that each organ or structure is somewhat less sensitive to teratogens, although damage may still occur. ADAPTED FROM MOORE & PERSAUD, 1993.
21 TERATOGENSDiseases of the pregnant womanRubella (German measles)Blindness, deafness, cardiac abnormalities, mental retardationMost dangerous during 1st trimesterNo woman should try to conceive unless they have had rubella or been immunized
22 TERATOGENSToxoplasmosis –Caused by eating undercooked meat, handling cat fecesCauses eye and brain damage during first trimesterInduces miscarriage later in pregnancy
23 Table 4.2 Common Diseases That May Affect an Embryo, Fetus, or Newborn
24 TERATOGENSSexually Transmitted DiseasesSyphilisCannot be transmitted to fetus until 18th weekEarly treatment prevents harmDamages eyes, ears, bone, heart, brainCan result in miscarriage
25 TERATOGENSSexually Transmitted DiseasesGenital HerpesCan cross placentaMost infections occur during birthKills 33% of infected newbornsCauses blindness, brain damage and other neurological problems in 25-30%Cesarean delivery prevents infecting newborn
26 TERATOGENSSexually Transmitted DiseasesAcquired Immunodeficiency Syndrome (AIDS)Caused by HIVPassed through placenta, while giving birth, or while breast-feedingOnly 25% of those at risk are infectedZDV reduces transmission by 70%50% of HIV infected infants live past 6
27 TERATOGENSDrugsThalidomideUsed to prevent nausea and vomitingTested on animals and was “safe”Caused birth defects (for some) if taken during first 2 months of pregnancyEyes, ears, noses, heartsPhocomelia – parts of limbs missing, feet or hands connected to torso
29 TERATOGENSDrugsAlcohol – compromises functioning of the placentaFetal alcohol syndrome (FAS)MicrocephalyMalformation of heart, limbs, joints and faceHyperactivity, seizures, tremorLower IQ, major adjustment problems
30 TERATOGENSAlcoholFetal Alcohol Effects (FAE)Social drinking (1-3 per day)Greatest risk – binge drinking (5+)Slow physical growth, poor motor skills, attention difficulties, verbal learning difficultiesSubnormal intellectual performanceFather’s drinking may also be harmful
31 TERATOGENSCigarette SmokingCleft lipAbnormal lung functioningMiscarriageLow-birth-weightEctopic pregnancy – implantation in fallopian tubeSudden Infant Death SyndromeHigher concentration of nicotine in fetus
32 TERATOGENSMarijuanaEmotional regulation in malesPoorer reading/spelling at 10 years oldMore depression/anxietyNarcotics (heroin, methadone)60-80% born addictedBreathing/swallowing coordinationNormal developmental progress by age 2, although boys remain vulnerable
33 TERATOGENSCocaineMiscarriage, premature birthSleep disturbances, very irritableLower IQPoor language development skillsNegative effects also due toMaternal vocabularyHome environmentExposure to additional teratogens
34 Table 4.3 Partial List of Drugs and Treatments Used by the Mother That Affect (or Are Thought to Affect) the Fetus or the Newborn
35 TERATOGENSEnvironmental HazardsRadiation – death, mental retardationChemicals/pollutantsLead/mercury – deformities, mental retardationPCB’s – less neurologically maturePrenatal and postnatal effectsFather’s exposure also harmful
36 Figure 4.6 Average cognitive test performance at age nine, based on child’s level of exposure to PCB prenatally and through breast feeding. Light bars indicate children who were exposed to low levels of PCB, dark bars are children who were exposed to high levels of PCB.
37 MATERNAL CHARACTERISTICS Pregnant Woman’s DietTotal weight gain pounds1st trimester malnutrition – miscarriage, spinal cord malformation3rd trimester malnutrition – low-birth-weight, small headsDietary supplements and stimulation can reduce effects of prenatal malnutrition
38 Figure 4.7 Incidence of infant mortality in the first 12 months for babies born to Dutch mothers who had experienced famine during World War II. ADAPTED FROM STEIN & SUSSER, 1976.
39 MATERNAL CHARACTERISTICS Pregnant Women’s DietMagnesium & Zinc – reduce complicationsFolic acid – reduces Down Syndrome, spina bifida, anencephalyMedical supervision is necessary, as excessive vitamin/mineral supplements can be harmful
40 MATERNAL CHARACTERISTICS Pregnant Woman’s Emotional Well-BeingProlonged and severe emotional stressStunted prenatal growthPremature deliveryIrritableIrregular feeding, sleepingCausal relationship in animals
41 Figure 4. 8 Percent of bath time infants spent fussing and crying Figure 4.8 Percent of bath time infants spent fussing and crying. The figure compares infants whose mothers experienced high levels of cortisol (a hormone related to stress) to infants whose mothers experienced low levels of cortisol during pregnancy.
42 Figure 4. 8 Percent of bath time infants spent fussing and crying Figure 4.8 Percent of bath time infants spent fussing and crying. The figure compares infants whose mothers experienced high levels of cortisol (a hormone related to stress) to infants whose mothers experienced low levels of cortisol during pregnancy. (continued)
43 MATERNAL CHARACTERISTICS Pregnant Women’s Emotional Well BeingProlonged stressStress hormones – impede oxygen and nutrients to fetusWeaken immune systemLinked to poor eating, smoking, drug and alcohol use – all harm fetusCounseling to manage/reduce stressModerate levels may aid development
44 MATERNAL CHARACTERISTICS Pregnant Woman’s Age – is optimal15 years old and youngerImpoverished backgroundsPoor nutrition, high stress, little prenatal careLittle risk if good prenatal care is presentOlder than 35Increased risk of miscarriageRisks not reduced by prenatal care
45 BOX 4.1 - FOCUS ON RESEARCH: FETAL PROGRAMMING Fetal Programming Theory – brain and other systems are programmed in a manner that is adaptive for the uterine environmentPersists at birth, but what’s adaptive in the uterus may not be after birthFocus is on subtle changes in metabolism, endocrine and autonomic functionsResult may be increased susceptibility to diseases in adulthood, like diabetes
46 PREVENTION OF BIRTH DEFECTS 95% of newborns are normalMany of remaining 5% have minor congenital problems that are temporary or correctableEach pregnancy is differentGenetic makeupPrenatal environment
47 Table 4.4 Reducing Likelihood of Congenital Disorders.
48 BIRTH AND THE PERINATAL ENVIRONMENT Perinatal environment – environment surrounding birthMedicationsDelivery practicesSocial environment
49 THE BIRTH PROCESSFirst stage of laborContractions minutes apartCervix fully dilatesSecond stage of labor – deliveryHead passes through cervixBaby emerges from bodyThird stage of labor – afterbirthPlacenta expelled from body
53 THE BABY’S EXPERIENCEAssessing the Baby’s ConditionNeonatal Behavioral Assessment ScaleSeveral days after birth20 inborn reflexesReactions to comforting and social stimuliUnresponsiveness may indicate neurological problemsCan be a parent teaching tool
54 LABOR AND DELIVERY MEDICATION Some medication used by 95% of mothersReduce pain, induce contractions, relax the motherCan reduce the ability to push effectivelyCan make babies lethargic and inattentiveDrugs in appropriate doses can increase comfort without disrupting delivery
55 BOX 4.2 – APPLYING RESEARCH TO YOUR LIFE: VARIATIONS IN BIRTHING PRACTICES Pokot of Kenya – community celebrationUttar Predesh in India – shameful, disgustingU.S. typically a hospital procedureNatural / prepared childbirth: focus is on support, relaxation – reduces medicationHome births – shorter labors, less meds, safe if smooth pregnancy, trained midwifeAlternative birthing centers – homelike setting in hospital
56 THE SOCIAL ENVIRONMENT SURROUNDING BIRTH Mother’s experienceFirst 6-12 hours – sensitive period for emotional bonding (not essential)Maternity blues – 40-60% of mothersPostpartum depression – 10% of mothersShould seek professional helpDepression affects outcomes of both mother and infant
57 THE SOCIAL ENVIRONMENT SURROUNDING BIRTH The Father’s experienceEngrossment – intense fascination, desire to touch, hold and caressEarly contact with newborn can make father feel closer to partner, positive support for mother
58 POTENTIAL PROBLEMS AT BIRTH Anoxia – oxygen deprivationUmbilical cord becomes tangledBreech positionPlacenta separationRH factor incompatibility – now preventableCan cause neurological damage, permanent disabilitiesIncreased risk of adult heart disease
59 POTENTIAL PROBLEMS AT BIRTH Complications of Low Birth WeightPreterm – born more than 3 weeks early, but appropriate weight for time in wombSmall for date – underweight due to slow fetal growth – greater risk than pretermCauses include smoking, drug use, stress, lack of prenatal care, multiple births, social support
60 [Figure Gestational age at birth for singletons, twins, and triplets.
61 POTENTIAL PROBLEMS AT BIRTH Short-term Consequences of Low Birth Weight40-50% weighing less than 2.2 pounds dieBrain development and neural pattern formation in preterm infants differsBreathing difficulty due to lack of surfactin, or respiratory distress syndromeSpend time in isolettesCan be frustrating to care for
62 POTENTIAL PROBLEMS AT BIRTH Interventions for Preterm InfantsEarly acquaintance programs – touching, rocking, talking, are developmentally beneficialParents can be taught how to be sensitive and responsive to preterm infantsCombined with stimulating day care programs help, improves cognitive growth and reduces behavioral disturbances
63 POTENTIAL PROBLEMS AT BIRTH Long-term Consequences of Low Birth WeightDepends on postnatal environmentStimulating home, very goodLess stable home or being economically disadvantagedSmaller, emotional problemsDeficits in intellectual/academic performance
64 Figure Age trends in intellectual development for low-birth-weight twins from middle-class (high SES) and lower socioeconomic (low SES) backgrounds. ADAPTED FROM WILSON, 1985.
65 REPRODUCTIVE RISK AND CAPACITY FOR RECOVERY Werner & Smith – Kauai Longitudinal StudyAt birth,16% severe complications, 31% mildAge 2 – severity predicted developmental progress, but emotional support and educational stimulation improved outcomesAge 10 – severity not very predictive, home environment now predictive
66 APPLYING DEVELOPMENTAL THEMES TO PRENATAL DEVELOPMENT AND BIRTH Active child – moves, practices in wombNature/nurture interaction – effects of teratogensQualitative changes – stages of birthQuantitative changes – fetal developmentHolistic nature of development – prenatal development affects all future development; social support during birth has consequences for future development