1. Conception and Development of the Embryo and Fetus
Chapter 7
Conception and Development of the Embryo and Fetus

2. Implantation
Zygote (cell that results from fertilization) propelled by
Cilia
Peristalsis
Reaches uterine cavity in 3 to 4 days

3. Nidation Occurs by 10th day after fertilization Implantation bleeding
Blastocyst (5 days after fertilization) is buried beneath the endometrial surface

5. Placenta Develops from trophoblast cells
Provides oxygenation, nutrition, waste elimination, and hormones
Protects fetus

6. Placental Hormones Human chorionic gonadotrophin (hCG)
Human placental lactogen (hPL)
Progesterone
Estrogen

7. Progesterone
A female hormone (ovaries) during the release of the mature egg from an ovary
Helps prepare the lining of the uterus to receive the fertilized egg
Produced by the placenta during pregnancy
What happens if fertilization does not occur?

8. Estrogen
For growth and development of female sexual characteristics and reproduction
Produced by the ovaries and the placenta
Prompts hyperplasia and hypertrophy (growth in the number of cells and size during pregnancy)
Breast tissue enlarges, uterus to expand, uterine contractility to prepare for labor

9. placenta

10. Umbilical Cord Usual location—center of placenta
55 cm long (21 in); 1 to 2 cm diameter
Vessels: one vein, two arteries
Wharton’s Jelly: protects umbilical cord from compression

12. Fetal Circulation
Heart begins to beat and circulate blood by end of third week
Umbilical vein: blood from placenta to fetus

13. Fetal Circulation Three unique shunts
Ductus venosus: bypasses liver and enters inferior vena cava
Foramen ovale: right and left atria to supply blood to head, and upper and lower extremities
Ductus arteriosus: returning blood bypasses lungs
Refer to figure 7-11

14. Fetal Circulation

16. Fetal Membranes and Amniotic Fluid

17. Embryonic Membranes Early protective structures Two separate membranes
Amnion—inner membrane, contains amniotic fluid
Chorion—outer membrane, forms fetal portion of placenta
Slightly adherent, form amniotic sac

18. Why is amniotic fluid index important in determining fetal well being?

19. Purposes of Amniotic Fluid
Protects and cushions fetus
Maintains normal body temperature
Symmetrical fetal growth
Freedom of movement
Essential for normal fetal lung development

20. Amniotic Fluid Fetal urine and lung secretions primary contributors
Slightly alkaline
Contains antibacterial, other protective substances

21. Threats to Embryonic and Fetal Development
Chromosomes and teratogens
Medications and other substances
Vitamins, alcohol, tobacco, caffeine, drugs, radiation, and lead
TORCH infections
Refer to table 7-4 for FDA’s 5 categories of safety
Refer to Box 7-1 for fetal risks associated with TORCH infections

22. Nurse’s Role in Prenatal Evaluation
Initial prenatal visit
Assessment:
cultural, emotional, physical, and physiological factors
Education
Teratogen exposures
Genetic disorders
Prenatal tests
Refer to table 7-5 for various diseases among certain racial & ethnic populations

23. Maternal Age and Chromosomes
Age 35 and above
Increased risk of chromosomal abnormalities
Down syndrome (trisomy 21)

24. Trisomy 18

25. Minimizing Threats to Embryo/Fetus
Nurse’s role
Assessment
Environmental and lifestyle risks
Knowledge
Physical and psychosocial well-being
Preconception counseling