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Chapter 3: Prenatal Development and Birth. In This Chapter.

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Presentation on theme: "Chapter 3: Prenatal Development and Birth. In This Chapter."— Presentation transcript:

1 Chapter 3: Prenatal Development and Birth

2 In This Chapter

3 Conception and Genetics Chromosomes, DNA, and Genes Process of conception  Ovum  Sperm  Zygote Chromosomes  DNA  Genes

4 Conception and Genetics Sex Determination Chromosomes  Autosomes  Sex chromosomes (X, Y) Chromosomal differences  Androgens and SRY gene  Sex chromosomes (X, Y)  Gonad development

5 Conception and Genetics Multiple Births Twins Identical (monozygotic) Fraternal (dizygotic) Semi-identical (different genes from father)

6 Stop and Think! Your textbook notes an increase in multiple births over the past thirty years. Why has this occurred?

7 Conception and Genetics How Genes Influence Development  Genotype: Genetic blueprint  Phenotype: Observable characteristics  Dominant–recessive pattern  Polygenic inheritance

8 Let’s Take a Look… Whose hair do you have? On the next slide you will see the genetics of hair type. Did you answer the above question correctly?

9 The Genetics of Hair Type

10 Conception and Genetics Other Types of Inheritance Genomic imprinting: Some genes biochemically marked at time ova and sperm develop Mitochondrial inheritance: Genes in mitochondria

11 Conception and Genetics Multi-Factorial Inheritance (MFI) MFI: Inheritance affected by genes and environment  Five general principles (Rutter et al.) In what ways have genetics and environment integrated to influence your development?

12 Genetic Disorders Autosomal Disorders Autosomal gene: One of 22 pairs of autosomes that are involved in sex determination Autosomal recessive disorder: 2 copies of the abnormal gene must be present for the disease or trait to develop. Autosomal dominant disorder: abnormal gene from 1 parent sufficient to inherit disease or trait See Table 3.2 for a summary of some genetic disorders.

13 Genetic Disorders Sex-Linked Disorders Sex-linked disorders: Caused by recessive gene on X chromosome

14 Stop and Think… Why do boys have Fragile X Syndrome more often than girls?

15 Chromosomal Errors Trisomies and Monosomies Trisomies: Three chromosomes, rather than usual pair Monosomies: Absence of one member of chromosome pair

16 Chromosomal Errors Sex Chromosome Anomalies  Trisomy 21: Down syndrome  XXY: Klinefelter’s syndrome  XO: Turner’s syndrome  XXX: girls with an extra X  XYY: boys with an extra Y

17 Pregnancy and Prenatal Development The Mother’s Experience: First Trimester Care Regular prenatal care critical at this time Problems Ectopic pregnancy, bleeding, miscarriage

18 Pregnancy and Prenatal Development The Mother’s Experience: Second Trimester Care  Monthly doctor visits continue  Ultrasound Problems  Gestational diabetes; Rh incompatibility; increased blood pressure  Miscarriage; premature labor

19 Pregnancy and Prenatal Development The Mother’s Experience: Third Trimester Care Weekly visits (beginning in 32nd week) Ultrasound to assess position, pelvic exam to check cervical dilation Problems  Increased blood pressure, bleeding, bladder infection  Premature labor

20 Pregnancy and Prenatal Development The Prenatal Experience: Germinal Stage Conception to implantation Blastocyst implants Specialization of cells needed to support development

21 Pregnancy and Prenatal Development The Prenatal Experience: Embryonic Stage 2 to 8 weeks after conception Neural tube develops Forms foundations of all body organs and systems Many organs and systems begin to function.

22 Pregnancy and Prenatal Development The Prenatal Experience: Fetal Stage End of week 8 until birth Growth from 1/4 ounce and 1 inch to 7 pounds and 20 inches in length Refinement of all organ systems Neuronal proliferation Viable at Week 24; full-term at Week 37

23 Figure 3.3: Parts of the Neuron Structure of a Single Neuron Cell bodies first to develop (wks 12-24) Axons and dendrites develop later (especially final 12 wks). Axons continue to increase in size and complexity after birth. Figure 3.3. Parts of the Neuron

24 Prenatal Sex Differences Males  More physically active  Higher rates of miscarriage  More vulnerable to prenatal problems Females  More sensitive to external stimulation  More rapid skeletal development

25 Prenatal Sex Differences Some researchers suggest:  Males  More physically active  More vulnerable to prenatal problems  Females  More sensitive to external stimulation  More rapid skeletal development Other researchers contend: Sex differences in: Prenatal hormones linked to cross-gender variations Prenatal problems Can you guess what these might be?

26 Prenatal Behavior Introducing the Amazing Fetus!  Fetuses can differentiate between familiar and novel stimuli by 32 to 33 weeks.  Newborns can remember prenatal stimuli and react accordingly.  Very active fetuses tend to be active children who can be labeled “hyperactive” later on.

27 Figure 3.6 Correlations between Fetal Behavior and Brain Development

28 You are told by a genetic counselor that you have 25 percent chance of passing on a deadly genetic trait to your child. Do you still have a child? What factors influence your choice? How do we curtail the use of teratogens, such as smoking and alcohol use, by pregnant women? Questions To Ponder

29 Teratogen: substance that can damage embryo See Figure 3.7 for timing of exposure Greatest damage during organ system’s most rapid development First 8 weeks most dangerous exposure time Duration and intensity exposure i mportant Problems in Prenatal Development Teratogens

30 Figure 3.7 Timing of Teratogen Exposure

31 Problems in Prenatal Development Teratogens: Drugs  Prescription  Over-the-counter drugs  Marijuana, methamphetamine, and heroin  Cocaine  Tobacco  Alcohol

32 Problems in Prenatal Development Teratogens: Maternal Diseases  Rubella (“German measles”)  HIV  Other sexually transmitted diseases

33 Problems in Prenatal Development Other Maternal Influences: Diet Folic acid deficiencies Malnutrition  Neonate low birth weight  Brain stunting  Fetal death  Mental illness in adulthood

34 Problems in Prenatal Development Other Maternal Influences: Age  First pregnancies are occurring later— average age is now 25.1 years.  Women over 35 have higher risks for pregnancy complications.  Teenage mothers have higher risks during and after birth.

35 Problems in Prenatal Development Other Maternal Influences: Chronic Illnesses Kinds of illness  Depression  Epilepsy  Diabetes  Lupus Prevention  Monitoring of mother and fetus necessary for most illnesses  Fetal–maternal specialist for high-risk patient

36 Problems in Prenatal Development Environmental Hazards Detrimental effects of hazards may be reduced by:  Limiting exposure to lead and mercury  Avoiding possible harmful chemicals

37 Problems in Prenatal Development Maternal Emotions  Maternal stress and depression related to higher risks for fetus  Social support and counseling may help.  Mixed information from research

38 Fetal Assessment and Treatment

39 Can you identify each method? Figure 3.8 Two Methods of Prenatal Diagnosis

40 Stop and Think! With the advent of antiretroviral drugs, the rate of mother-to-fetus transmission has been greatly reduced. Do these findings justify mandatory testing and treatment of pregnant women who are at high risk of having HIV/AIDS?

41 Birth and the Neonate Birth Choices Things to consider  Location of birth  Birth attendants  Drugs during labor and delivery  “Natural childbirth”

42 Want to make a birth plan? How would you plan the ideal birth for yourself, a partner, or a friend? Go to the link below to develop your birth plan. Did you include everything in your above ideal plan? n.html

43 The Physical Process of Birth Labor: An Overview Stage 1  Contractions  Dilation of the cervix Stage 2  Actual delivery of the baby Stage 3  Delivery of the placenta and umbilical cord

44 Figure 3.9 The Three Stages of Labor


46 The Physical Process of Birth Birth Complications: Cesarean Deliveries  Why are Cesarean deliveries performed?  Fetal distress  Breech presentation  Birth size  Poor progress during labor  Mother’s health and age concerns

47 The Physical Process of Birth Assessing the Neonate  Apgar scale  Brazelton Neonatal Behavioral Assessment Why is neonatal assessment important?

48 Assessing the Neonate Low Birth Weight Babies (LBW) LBW: below 2,500 grams (5.5 pounds) Preterm: mostly born before Week 38 Small-for-date neonates Risks Respiratory distress syndrome Intervention Adequate parental education and support reduces risk of complications.

49 Assessing the Neonate Do LBW babies catch up?  Development best assessed on individual basis  Two-thirds to three-fourths of preterm infants catch up by school entrance.  Lowest birth weight and earlier gestational age associated with long-term developmental delays.

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