Presentation on theme: "PSYC 2314 Lifespan Development"— Presentation transcript:
1 PSYC 2314 Lifespan Development Chapter 4Prenatal Development and Birth
2 Stages of Prenatal Development Germinal periodFirst two weeksWithin hours after conception, the one-cell zygote travels down the Fallopian tube toward the uterus and begins the process of cell division and growth
3 Stages of Prenatal Development Germinal periodSoon, differentiation occurs, a process first clearly seen when the multiplying cells separate into two distinct masses, one inside the other. The outer cells will become the placenta; the inner cells form a nucleus that will become the embryo.If all goes well, implantation of the cell mass occurs.
4 Stages of Prenatal Development Embryonic periodBegins as the organism begins differentiating into three layers, each of which will become a key body system.A fold in the outer layer of cells becomes the neural tube, which will become the brain and spinal column (the central nervous system).
5 Stages of Prenatal Development Embryonic periodIn the fourth week, the cardiovascular system is functioning; the eyes, ears, nose, mouth start to form.At five weeks, the arm and leg buds appear and the embryo is about ¼ inch long.By the end of the second month, the developing organism weighs about 1 gram, is 1 inch long, and has all the basic organs (except the sex organs) and features of a human being.
6 Stages of Prenatal Development Fetal periodDuring the third month, the sex organs begin to take shape.During the early weeks of life, the placenta develops rapidly. This organ connects the circulatory system of the mother with that of her growing embryo, allowing nourishment to flow to the developing organism and transporting wastes away.The first stage of development of the sex organs is the appearance of the indifferent gonad during the sixth week. If the fetus is male (XY), a gene on the Y chromosome sends a biochemical signal after about seven weeks that triggers the development of male sex organs. If the embryo is female, no signal is sent, and the fetus begins to develop female sex organs.
7 Stages of Prenatal Development Fetal periodIn the mid three months, the systems develop more fully. The crucial factor in the fetus’s attaining the age of viability, beginning at about 22 weeks, is brain maturation, which is essential to the regulation of the basic body functions of breathing, sucking, and sleeping.By 28 weeks, the typical fetus weighs about 1,300 grams (3 lbs.) and has a greater than 90 % chance of survival.
8 Stages of Prenatal Development Fetal periodDuring the last 3 months, the respiratory and cardiovascular systems mature dramatically.Weight gain during last weeks stores fat, which will provide a layer of insulation when the child is no longer surrounded by the mother’s warmth. The weight gain also provides nourishment and vitamins that will be used until the mother’s breast milk is fully established.
9 Fetus’s Responses Physiological interdependence Fetal movements HearingPhysiological interdependence: fetus is affected by every aspect of mom’s lifestyle and the expectant mom is affected by the development of the fetus—with nausea, increased urination, and digestive upsets, gestational diabetes, high blood pressure, and toxemia.Fetal movements usu. evoke feelings of wonder.Most mothers-to-be are well aware that their fetus can hear, having felt the developing person quiet down when they sing a lullaby or startle with a kick when a door slams. But many people do not realize that newborns remember certain sounds heard before birth. The most obvious example is that infants typically stop crying when they are held with an ear close to the mother’s heart, comforted by the familiar rhythm they have heard for months. Few mothers know this explicitly, but most instinctively cradle their infants their left side rather than their heartless right.Remember voices as well.
10 Teratology The scientific study of birth defects A science of risk analysis, which attempts to evaluate what factors can make prenatal harm more, or less, likely to occur.Teratogens—substances or conditions as viruses, drugs, chemicals, stressors, and environmental hazards.
11 3 Crucial Factors Timing of exposure Amount of exposure Developing organism’s genetic vulnerability to damage from the substance
12 Critical periods Physical structure and form-embryonic For conditions (such as severe malnutrition) and substances (such as heroin), that disrupt and destabilize the overall functioning of the woman’s body, there are two critical periods: the very beginning and the near the end of the pregnancyCritical period: the time of greatest susceptibility
13 Critical periodsAt the very beginning, when stress during the germinal period can impede implantation.Near the end, when the fetus most needs to gain weight and when the cortex of the brain is developing, making the fetus particularly vulnerable to damage that can cause learning disabilities.
14 Critical periodsAlso, instability of the mother’s body systems (chills, shakes, etc.) can loosen the placenta or cause hormonal changes, both of which can precipitate birth.For behavioral teratogens there is no safe period. The brain and nervous system can be harmed throughout the prenatal development.
15 Amount of ExposureThreshold effect: the substance is virtually harmless until exposure reaches a certain frequency or dosage.Interaction effect: the combination of threshold teratogens taken together may make them more harmful at lower dosage levels than they would be individually.Interaction effect: one poison intensifies the effects of another.
16 Genetic Vulnerability Susceptibility to alcoholism involves a genetically related defect in a specific enzyme.A deficiency in folic acid in the mother’s diet may also result in genetic defects.Males not only have a higher rate of teratogenic birth defects and later teratogen-related behavioral problems, but also a higher rate of spontaneous abortions.
17 Teratogens Rubella (German measles) Human Immunodeficiency Virus (HIV) If contracted early in pregnancy, it can cause blindness, deafness, heart abnormalities, and brain damage.Human Immunodeficiency Virus (HIV)A pregnant women with HIV may pass the virus on to her fetus either during pregnancy or childbirth. Infants who have HIV will eventually develop pediatric AIDS.Rubella: first teratogen to be recognized. If contracted early in pregnancy, it can cause blindness, deafness, heart abnormalities, and brain damage. It can now be curbed by immunization.HIV: a pregnant woman with HIV may pass the virus on to her fetus either during pregnancy or childbirth. Infants who have HIV will eventually develop pediatric AIDS.The best way to prevent pediatric AIDS is to prevent adult AIDS. The second best way is to prevent pregnancy in HIV-positive women. A third preventive measure is administering the drug AZT to HIV-infected women during pregnancy and at birth.
18 Teratogens Psychoactive Drugs Slow fetal growth, contribute to premature labor, and may produce both short- and long-term brain deficits.Psychoactive drugs: beer, wine, liquor, cigarettes, and smokeless tobacco, heroin and methadone, LSD, marijuana, cocaine, inhalants, and antidepressants.
19 Teratogens Alcohol Consumption Large doses of alcohol can trigger the physical, behavioral, and mental symptoms of fetal alcohol syndrome (FAS).Even moderate alcohol consumption during pregnancy (more than ½ ounce of absolute alcohol) can produce the intellectual impairment of fetal alcohol effects (FAE).Likely victims of FAS, which is the leading known prenatal cause of mental retardation in the industrialized world, are those whose mothers drink more than three drinks daily during pregnancy.
20 TeratogensSmokingIncreases the risk of abnormalities and reduces birthweight and size; babies whose mothers smoked are shorter at birth and in the years to come. They are also more likely to have respiratory problems.
21 TeratogensDrugsPrenatal exposure to marijuana has been linked to central nervous system impairment.Exposure to heroin causes slower fetal growth and premature labor.Cocaine use during pregnancy retards fetal growth, increase the risk of problems with the placenta, and often leads to early learning difficulties.
22 Protective Measurements Complete abstinence from drugs even before pregnancyAbstinence after the first monthModeration throughout pregnancy (if abstinence is not possible)Minimizing maternal stress by seeking social supportObtain good postnatal careSteps to take to protect babies against the harmful effects of drugs.
23 Birthweight Low birthweight (LBW) Preterm Less than 5 ½ lbs.PretermLBW infants who are born more than 3 weeks earlySGA (small for gestational age)Infants born close to the due date but weighing less than most full-term newborns.Possible causes for preterm:Placenta may become detached from the uterine wallA uterus may be unable to accommodate the further fetal growthConditions that disrupt the physiological equilibrium of the mother (such as a high dose of psychoactive drugs, extreme stress, or chronic exhaustion)Vaginal infectionMore often, general factors in the woman are the cause, which explains why having had one preterm birth is a risk factor for having another.SGA—very psychoactive drug slows growth, but tobacco is the worst!
24 Poverty and LBWPregnant women at the bottom of the SES are more likely to be ill, malnourished, teenaged, and stressedIf they are employed, their jobs often require long hours of physically stressful work, exactly the kind that correlates with preterm and SGAThey often receive late or inadequate prenatal care, breathe polluted air, live in overcrowded conditions, ingest unhealthy substances
25 Normal BirthBegins at about the 266th day after conception, when the fetus’s brain signals the release of hormones that trigger uterine contractions in the mother.The first stage of labor (until the baby’s head emerges from the birth canal) usually lasts 6 hours in first births and 3 hours in subsequent births.
26 Apgar ScaleUsed to assign score between 0 and 2 to the newborn’s heart rate, breathing, muscle tone, color, and reflexes at 1 minute after birth and again at 5 minutes.A score of 7 or better indicates the newborn is not in danger; below 7, infant needs help in establishing normal breathing; and below 4, the baby is in critical condition.Criteria and Scoring of the Apgar Scale: p. 118 and Table 4.6
27 Medical Attention/Intervention Medical procedures are overused: episiotomies and C-sectionsRoutine procedures: IV, fetal monitoring, are rooted in tradition rather than in medical necessity.
28 Birth ComplicationsBirth complications are more likely if the fetus is already at risk because of low weight, preterm birth, genetic abnormality, or teratogenic exposure.Researchers now realized that cerebral palsy (difficulties with movement control resulting from brain damage) results from genetic vulnerability, worsened by teratogens and a birthing process that includes anoxia (a temporary lack of oxygen).
29 Birth ComplicationsMany hospitals now provide high-risk infants with regular massage and soothing stimulation.When they are brought home, high-risk infants are often more distractible, less obedient, and slower to talk. However, long-term impairment is not inevitable.
30 Parent-newborn BondEmphasize the tangible as well as the intangible attachment of parent to child in the early moments after birth.Diane Eyer-bonding is a social construction that developed as a reaction against the medicalization and depersonalization of traditional hospital births.Extensive research has shown that the events right after birth are just one episode in a long-term process of bonding between parent and child.