1. CONCEPTION FETAL DEVELOPMENT & GENETICS Chapter 10
Mary L. Dunlap MSN,
Fall 2015

3. Fetal Development Measured in the number of weeks after fertilization
Average pregnancy lasts 280 days or 40 weeks from the date of the last menstrual period (LMP)
Fertilization usually occurs 14 days after the LMP

4. Three Stages of Fetal Development
Preembryonic stage: fertilization through the second week
Embryonic stage: end of second week through the eighth week
Fetal stage: ninth week until birth

5. Preembryonic Stage (Stage 1)
Fertilization - union of the ovum and sperm in the outer 3rd of the fallopian tube creating a zygote
The union restores the diploid number of 46 chromosomes

6. Fetal Development
Fertilization

8. Preembryonic Stage (Stage 1)
Zygote undergoes cleavages (mitosis) as it is transported to the uterine cavity in 72⁰
Cleavages create a ball of 16 cells called a morula, which divides into cells that form fetal structures

10. Preembryonic Stage (Stage 1)
Blastocysts - inner cells form the embryo and the amnion
Trophoblasts - outer cells form the embryonic membranes, Chorion and placenta
Implantation in the endometrium occurs between the 7th to 10th day.

11. Embryonic Stage (Stage 2)
Fetal membranes start forming
around the time of implantation
Decidua- endometrial linning
Chorion-placenta
Embryonic germ layers- ectoderm, mesoderm, endoderm
Amnion- lines the amniotic sac & forms the umbilical cord

12. Embryonic Stage (Stage 2)
Amniotic Fluid
Surrounds embryo,
Helps maintain a constant body temperature for the fetus
Permits symmetric growth and development
Cushions the fetus from trauma

13. Embryonic Stage (Stage 2)
Amniotic Fluid Function
Allows the umbilical cord to be relatively free of compression
Promotes fetal movement to enhance musculoskeletal development

14. Embryonic Stage (Stage 2)
Umbilical cord
Life line between mother and embryo
1 large vein & 2 small arteries (AVA)
Wharton’s jelly surrounds the blood vessels preventing compression
Term length 22 in. / 1 in. wide
Central insertion site on the placenta

15. Embryonic Stage (Stage 2)
Placenta
Functioning by end of the 3rd wk.
Produces hormones that control the basic physiology of the mother and near term mature fetal organs for life outside of the uterus
Protects the fetus from immune attack by the mother
Removes waste produced by the fetus

16. Embryonic Stage (Stage 2)
Placental barrier prevents the mix of maternal blood with fetal blood
Placental Hormones
Human chorionic gonadotropin (hCG)
Human placental lactogen (hPL)
Estrogen, progesterone
Relaxin

17. Embryonic Stage
Maternal Fetal circulation via the placenta

18. Development Embryonic and Fetal Development Table 10-1 p 286-287
Use pictures and models
4 wk.
5 wk.
6 wk.

19. Development
Fetal Development

20. Embryonic stage 3rd to 8th wk.
Development
Embryonic stage 3rd to 8th wk.
Neural tube forms
Brain waves detectable
Heart development completed and beats
Arms and legs move
Resembles a human being
Weight 1gram

21. Fetal Stage (Stage 3) 9Th week to Birth
12 wks.- heart beat heard with Doppler, sex is distinguishable, placenta formation completed
13-16 wks.- fetal movement (quickening) felt by mother
17-20 wks.- heart beat can be heard with a stethoscope
All major systems are present- they need to grow & finish developing

22. Fetal Stage (Stage 3) 21-24 wks.- lungs produce surfactant
24-32 wks.- alveoli begin to mature, eyelids can open and close, increase in subcutaneous fat
32-40 wks.- fetus kicks actively, lanugo decrease, weight 7-8 lb’s
Length in

23. 12-15 wk. fetus

24. Fetal Circulation Needed to sustain the fetus
Must develop quickly and accurately since the fetal nutrient needs Increase as the embryo advances to a fetus
Oxygen received from the placenta
Placenta functions for the fetal lungs and liver
Carries highly oxygenated blood to vital organs ( heart, brain) while shunting away
From less vital organs (lungs, liver)

25. Fetal Circulation Three unique shunts Ductus Venosus Foramen Ovale
Ductus Arteriosus
Fetal Circulation Prior to Birth
Foramen Ovale & Ductus Arteriosus
Ductus Venosus bypass liver & inters inferior vena cava
Foramen Ovale- shunt blood from R to L atria
Ductus Arteriosus- returning blood bypasses lungs, connects main pulmonary artery to aorta
Fetal Circulation
Placenta → umbilical vein →small amount of blood goes to liver via portal vein →remainder shunted away
through Ductus Venosus to Inferior vena cava → to R Atrium where blood is shunted through an opening
to the L Atrium flowing to the brain & upper extremities→ the remainder travels from the R atrium to the
R ventricle Through the pulmonary artery to the nonfunctioning lungs→ returning blood is shunted through
the Ductus Arteriosus →Descending aorta

26. Fig
Pg.- 291

27. Genetics Human Genome Project 1990 International 13 year study
Goal map the human genome
Better understanding how genetic changes contribute to disease
Helped develop new strategies for prevention, diagnosing and treating diseases and disorders

28. Genetics
Genetic services are becoming an integral part of medical care.
Diagnostic procedures have provide the opportunity to increase survival rates.
Nursing needs basic knowledge to be able to help their patients.

29. Genetic Disorders
Result from abnormalities in patterns of inheritance or chromosomal abnormalities

30. Chromosomal Abnormalities
1 in 33 infants born in the U.S. have birth defects and genetic disorders
Numeric abnormalities
Structural abnormalities

31. Numeric Abnormalities
Often result due to failure of the chromosome pair to separate
Few of these abnormalities are compatible with normal development and end in spontaneous abortion
Two common abnormalities Monosomies and Trisomies

32. Numeric Abnormalities
Monosomies-missing a chromosome only one instead of a pair
Trisomies - three of a particular chromosome
Trisomy 21(Down syndrome)

34. Structural Abnormalities
Breakage and loss of a portion of one or more chromosomes and the broken ends rejoin incorrectly
Altered structure can be a deletion, duplication, inversion or translocation
Mutation

35. Structural Abnormalities
Cystic fibrosis
Phenylketonuria
Sickle cell
Tay-Sacks

36. Structural Abnormalities
Huntington's disease
Polycystic kidney disease
Cri du Chat syndrome
Fragile X syndrome

37. Threats to Development
The following are capable of inducing abnormal fetal structure or function by interfering with normal fetal development
Teratogens
Medications
TORCH infections
Placenta functioning end of 3rd wk
Teratogens- alcohol, tobacco, caffeine, recreational drugs
TORCH
T- Toxoplasmosis single cell parasite uncooked meat cat feces & soil
causes damage to fetal eyes & brain
O- other infections chicken pox HIV Syphilis congenital abnormalities
R- rubella mental retardation
C- cytomegalovirus
H- herpes

38. Genetic Evaluation and Counseling
Genetic counseling is an evaluation of an individual to confirm, diagnose or rule out a genetic condition.

39. Genetic Evaluation and Counseling
Ideal time: before conception
“ preconception counseling provides
the opportunity to identify, reduce,
and plan for potential risks.

40. Genetic Evaluation and Counseling
Reasons an individual should be referred to genetic counseling (see Box 10-2 Pg.302)

41. Genetic Evaluation and Counseling
Genetic Testing
Genetic Counseling
Discussion about Genetic Counseling

42. Nurse’s Role
Discussing costs, benefits, and risks of using health insurance, and potential risks of discrimination
Recognizing ethical, legal, and social issues
Safeguarding privacy and confidentiality
Monitoring emotional reactions after receiving information

43. Nursing Role Providing emotional support
Referring to appropriate support groups
Beginning the preconception counseling process and referring for further genetic information
Taking a family history (Box 10-4 Pg. 257)

44. Nursing Role
Scheduling genetic testing
Explaining the purposes, risks/benefits of all screening and diagnostic tests (see Laboratory and Diagnostic Tests 10-1 Pg. 258)
Answering questions and addressing concerns

45. Prenatal Testing and Hard Choices

46. Antepartum Testing
Understanding Prenatal testing

47. Antepartum Testing Alpha-fetoprotein Amniocentesis
Chorionic villus sampling
Percutaneous umbilical blood sampling
Fetal nuchal translucency
Level II ultrasound
Triple marker test

48. Antepartum Testing Alpha-fetoprotien Diagnostic Amniocentesis
Chorionic Villus Sampling CVS
Percutaneous umbilical blood sampling PUBS
Fetal nuchal translucency
Types of Ultrasounds 7 min
Quad screen