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1. Introduction

1. Introduction. 2. Fact or Fiction?. 3. From Zygote to Newborn . 4. Vulnerability during Prenatal Development. 5. The Birth Process. 6. The Newborn. 7. Closing Thoughts. 2. Introduction. [Video: Prenatal Development and Birth Introduction]. 3. Fact or Fiction?. Fiction. Fact.

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1. Introduction

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  1. 1. Introduction 2. Fact or Fiction? 3. From Zygote to Newborn 4. Vulnerability during Prenatal Development 5. The Birth Process 6. The Newborn 7. Closing Thoughts 2

  2. Introduction [Video: Prenatal Development and Birth Introduction] 3

  3. Fact or Fiction? Fiction Fact 1. An embryo is the developing human organism between the third and eighth week after conception. 2. By the end of the third month, the fetus has all of its body parts. 3. Teratogens are only a concern for women who use alcohol and drugs. 4. All newborn reflexes help a baby survive. 4

  4. What is the timing and terminology of pregnancy? Popular and professional books use various phrases to segment pregnancy. The following comments may help to clarity the phrases used. Pregnancy begins at conception, which is also the starting point of gestational age. However, the organism does not become anembryountil about two weeks later, and pregnancy does not affect the woman (and cannot be confirmed by blood or urine testing) until implantation. Beginning of pregnancy Length of pregnancy Full-term pregnancies last 266 days, or 38 weeks, or 9 months. Instead of germinal period, embryonic period, and fetal period,some writers divide pregnancy into three-month periods called trimesters. Trimesters Although doctors assign a specific due date (based on the woman’s LMP), only 5% of babies are born on that exact date. Due date 5

  5. The First 14 Days implantation: The process beginning about 10 days after conception, in which the developing organism nestles in, and attaches to the placenta that lines the uterus. How does implantation occur? The Most Dangerous Journey Conception Zygote (single cell) Two-celled stage Fallopian tube Ova Sperm Ovum Implantation Ovary 6

  6. From the Third Through the Eighth Week What happens during the embryonic period of prenatal development? The intestines begin to move from the umbilical cord to the embryo’s body cavity. As nerves and muscles form links to the brain, the embryo now moves spontaneously, as the brain begins to move muscles. Intestines Brain Arms are well formed, longer, and can bend at elbows and move forward. Fingers elongate and digits are fully separated. Each finger has three digits, and the thumb has two digits. Eyes and eyelids are developed. Eyes will continue to migrate to the front of the head, where they will eventually rest. Eyelids begin to grow together and are only half closed. External, middle, and inner ears are now fully formed. External ears will continue to migrate to the side of the head, where they will eventually rest. Arms, hands and fingers Facial Features Urogenital membranes have developed into either male or female organs, and ovaries or testicles are visible. Clitoris or penis begins to form, but distinguishing the embryo’s sex is difficult. External sex organs Brain Facial Features The head is still disproportionately large but is erect and appears rounded. The neck is well defined. The tail will disappear by the end of this week. Cartilage begins to turn into bone. The ectoderm layer is replaced by the beginnings of skin. The body becomes evenly rounded, due to the growth in the abdomen. Arms, hands and fingers Intestines Overall appearance External sex organs Overall appearance 7

  7. From the Third Through the Eighth Week [Video: Germinal and Embryonic Periods] 8

  8. From the Ninth Week until Birth What happens during the fetal period of prenatal development? 9 weeks through 38 weeks 9 12 16 20 24 28 32 36 38 fetus: A developing human organism from the start of the ninth week after conception until birth. 9

  9. Prenatal Growth of the Brain Hindbrain Neural tube (forms spinal cord) Brain stem Midbrain Forebrain (a) 25 days Prenatal Brain Development How does the brain grow during the periods, or stages, of prenatal development? (b) 50 days (c) 100 days (d) 20 weeks (e) 28 weeks (f) 36 weeks (full term) 10

  10. From the Ninth Week until Birth [Video: Brain Development Animation: Prenatal] 11

  11. Making it to Birth What percentage of zygotes make it through each prenatal period? The Germinal Period At least 60 percent of all developing organisms fail to grow or implant properly and thus do not survive the germinal period. Most of these organisms are grossly abnormal. The Embryonic Period About 20 percent of all embryos are aborted spontaneously*, most often because of chromosomal abnormalities. The Fetal Period About 5 percent of all fetuses are aborted spontaneously before viability at 22 weeks or are stillborn, defined as born dead after 22 weeks. Birth About 31 percent of all zygotes grow and survive to become living newborn babies. *Spontaneous abortions are also called miscarriages. This table does not include induced abortions. Sources: Bentley & Mascie-Taylor, 2000; K.L. Moore & Persaud, 2003. 12

  12. What are the risks at different stages of development? Birth Defects from Teratogens: Time of Exposure and Effect on Major Organs Germinal Period Main Embryonic Period (in weeks) Fetal Period (in weeks) 1 2 3 4 5 6 7 8 9 16 32 38 Common site(s) of action of teratogens Highly critical period Less critical period Neural-tube defects Central nervous system Mental retardation Learningdisabilities Heart Arms Legs Cleft lip Lips Low-set malformed ears and deafness Ears Eyes Cataract, glaucoma Enamel staining Teeth Cleft palate Palate Masculinization of female genitalia Sex organs Teratogens often prevent implantation Major congenital anomalies Functional defects and minor anomalies 13 Source: Adapted from K.L. Moore & Persaud. 2003

  13. Benefits of Prenatal Care What are some prenatal tests? 14

  14. Benefits of Prenatal Care [Video: Sonogram] 15

  15. How do you feel about viewing the birth process? • 1. A close friend or relative asks you to be present during the labor and at the birth of her child. You feel like saying: • Yes, I want to be there! • Yes, if you need me. • Maybe; let me think about it. • It’s something I don’t think I can do. • Don’t know; it’s hard to imagine. • 2. You learn that someone took a photograph of the moment of your birth. Are you: • Very eager to see the photograph? • Interested in seeing the photograph at some time? • Turned off by the thought of the photograph? • Both interested and turned off by the idea of the photograph? • Don’t know. • 3. You learn that your class is scheduled to see a film of a birth. Are you: • Very interested in seeing the film? • Somewhat interested in seeing the film? • Somewhat uneasy about seeing the film? • Very uneasy about seeing the film? • Both interested and uneasy? 16

  16. [Video: Birth] 17

  17. First Minutes and Complications apgar scale: A quick assessment of a newborn’s health, given twice (at one minute and five minutes after birth). How is a Newborntested? 18

  18. First Minutes and Complications [Video: Apgar Test] 19

  19. Variations in Birth Weight Low Birth Weight (LBW): A body weight at birth of less than 5 ½ pounds (2,500 grams). Very Low Birth Weight (VLBW): A body weight at birth of less than 3 pounds, 5 ounces (1,500 grams). Extremely Low Birth Weight (ELBW): A body weight at birth of less than 2 pounds, 3 ounces; (1,000 grams). Why is birth weight important? Lagging physical and cognitive development confronts babies born early (or preterm, once called premature), and a preterm baby also is probably low birth weight. Play video: Low Birth weight in India Play video: An Observation of Premature Infants Clip E Play video: An Observation of Premature Infants Clip F 20

  20. Variations in Birth What are some newborn reflex experiences? Breathing reflexes Sucking reflexes Stepping reflexes Moro reflexes reflex: An unlearned, involuntary action or movement in response to a stimulus. 24

  21. Reflexes [Video: Newborn Reflexes] 25

  22. Social Support What is a father’srole? couvade: Symptoms of pregnancy and birth experienced by fathers. 26

  23. Social Support [Video: The Experience of Pregnancy: The First Trimester] 27

  24. Closing Thoughts From what you discovered about prenatal developmentin these slides, what examples can you cite to support the statement, “The most dramatic and extensive transformation of the entire life span occurs before birth?” 28

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