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FETAL DEVELOPMENT

FETAL DEVELOPMENT. Courtesy of: Peggy Pannell RN, MSN. Learning Outcome:. 2c) Students will be able to identify and describe all stages of typical fetal development From ovulation to birth From Conception to Birth. Blastocyst Conception Embryo Fertilization Fetus HCG Implantation.

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FETAL DEVELOPMENT

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  1. FETAL DEVELOPMENT Courtesy of: Peggy Pannell RN, MSN

  2. Learning Outcome: 2c) Students will be able to identify and describe all stages of typical fetal development • From ovulation to birth From Conception to Birth

  3. Blastocyst Conception Embryo Fertilization Fetus HCG Implantation Gestational age Vernix Zygote Placenta Quickening Umbilical Cord Selected Vocabulary:

  4. FERTILIZATION • Begins with 46 pair of chromosomes, splits off to 23 then combine for a unique new 46 pair.

  5. Stages and Time Frames

  6. First weeks of human development: Blastocyst embedded in endometrium. IMPLANTATION

  7. GESTATIONAL AGE • Gestational age=Time since last menstrual period (LNMP -Last Normal Menstrual Period) • Fertilization LNMP Days 280 Weeks 40 Calendar Months 9 Lunar Months 10

  8. TRIMESTERS Trimester 1st = weeks 1-13 2nd = weeks 14 - 26 3rd = weeks 27 and on (38-40 WEEKS)

  9. STAGES OF DEVELOPMENT

  10. Baby Center Video: Weeks 1-9 First TrimesterAt the end of four weeks: Baby is 1/4 inch in length Heart, digestive system, backbone and spinal cord begin to form Placenta (sometimes called "afterbirth") begins to develop The single fertilized egg is now 10,000 times larger than size at conception 1 Month

  11. First TrimesterAt the end of 8 weeks: Baby is 1-1/8 inches long Heart is functioning Eyes, nose, lips, tongue, ears and teeth are forming Penis begins to appear in boys Baby is moving, although the mother can not yet feel movement Month 2

  12. Baby Center Video: Weeks 10-14 First TrimesterAt the end of 12 weeks: Baby is 2 1/2 to 3 inches long Weight is about 1/2 to 1 ounce Baby develops recognizable form. Nails start to develop and earlobes are formed Arms, hands, fingers, legs, feet and toes are fully formed Eyes are almost fully developed Baby has developed most of his/her organs and tissues Baby's heart rate can be heard at 10 weeks with a special instrument called a Doppler Month 3

  13. Baby Center Video: Weeks 15-20 Second TrimesterAt the end of 4 months: Baby is 6 1/2 to 7 inches long Weight is about 6 to 7 ounces Baby is developing reflexes, such as sucking and swallowing and may begin sucking his/her thumb Tooth buds are developing Sweat glands are forming on palms and soles Fingers and toes are well defined Sex is identifiable Skin is bright pink, transparent and covered with soft, downy hair Although recognizably human in appearance, the baby would not be able to survive outside the mother's body Month 4

  14. Baby Center Video: Weeks 21-27 Second TrimesterAt the end of 5 months: Baby is 8 to 10 inches long Weight is about 1 pound Hair begins to grow on baby's head Soft woolly hair called lanugo will cover its body. Some may remain until a week after birth, when it is shed. Mother begins to feel fetal movement Internal organs are maturing Eyebrows, eyelids and eyelashes appear Month 5

  15. Second TrimesterAt the end of 6 months: Baby is 11 to 14 inches long Weight is about 1 3/4 to 2 pounds Eyelids begin to part and eyes open sometimes for short periods of time Skin is covered with protective coating called vernix Baby is able to hiccup Month 6

  16. Baby Center Video: Weeks 28-37 Third TrimesterAt the end of 7 months: Baby is 14 to 16 inches long Weight is about 2 1/2 to 3 1/2 pounds Taste buds have developed Fat layers are forming Organs are maturing Skin is still wrinkled and red If born at this time, baby will be considered a premature baby and require special care Month 7

  17. Third TrimesterAt the end of 8 months: Baby is 16 1/2 to 18 inches long Weight is about 4 to 6 pounds Overall growth is rapid this month Tremendous brain growth occurs at this time Most body organs are now developed with the exception of the lungs Movements or "kicks" are strong enough to be visible from the outside Kidneys are mature Skin is less wrinkled Fingernails now extend beyond fingertips Month 8

  18. Third TrimesterAt the end of 9 months: Baby is 19 to 20 inches long Weight is about 7 to 7 1/2 pounds The lungs are mature Baby is now fully developed and can survive outside the mother's body Skin is pink and smooth Baby settles down lower in the abdomen in preparation for birth and may seem less active Month 9

  19. AMNIOTIC FLUID • Protects Fetus • Controls Temperature • Supports Symmetrical Growth • Prevents Adherence to amnion • Allows Movement • Source of oral fluid • Acts as a excretion-collection repository • Clear, yellowish fluid surrounding the developing fetus. • Average amount 1000 ml.

  20. UMBILICAL CORD Connecting link between fetus and placenta. • Transports oxygen and nutrients to fetus from the placenta and returns waste products from the fetus to the placenta. • Contains: 2 arteries and 1 vein supported by mucoid material (wharton’s jelly) to prevent kinking and knotting. • Contains NO pain receptors.

  21. PLACENTA

  22. Schematic drawing of placenta: how it supplies oxygen and nutrition to embryo and removes waste products. Deoxygenated blood leaves fetus through the umbilical arteries and enters placenta, where it is oxygenated. Oxygenated blood leaves placenta through the umbilical vein, which enters the fetus via the umbilical cord PLACENTA mom MOM Baby Baby

  23. PLACENTA Produces protein hormones: • Human chorionic gonadotrophin (HCG)- 8-10 days past conception, is basis for pregnancy test • Progesterone • Estrogen • Human Placental Lactogen

  24. PLACENTA • Sieve/filter – allows smaller particles through and holds back larger molecules. Passage of materials in either direction is effected by: • Diffusion: gases, water, electrolytes • Facilitated transfer: glucose, amino acids, minerals. • Pinocytosis: movement of minute particles

  25. PLACENTA • Mother transmits immunoglobulin G (IgG) to fetus providing limited passive immunity. • Leakage: caused by membrane defect: may allow maternal and fetal blood mixing.

  26. Capability of fetus to survive outside uterus at the earliest gestational age - 22-24 weeks Survival depends on: Maturity of fetal central nervous system Maturity of lungs VIABILITY

  27. NEUROLOGICAL SYSTEM • Formed during the 3rd week • Respiratory effort 18 1/2 WKS • Swallowing 12 1/2 WKS • Fetal movement felt 16-20 WKS (Quickening) • Sucking 29 WKS

  28. IMMUNE SYSTEM • Passive immunity - FROM MOM • Active immunity - FROM FETUS

  29. What Now? Using your notes for support, work with a partner to fill out the activity handout entitled “When’s That”? Be prepared to discuss your answers with the class. 

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