Fetal Development

FETAL DEVELOPMENT
Presentation by:Peggy Pannell RN, MSN

Learning Goals
* Normal Fetal Development
o From ovulation to birth
* Teratogen
o Definition and potential effects on development
Vocabulary
* Blastocyst
* Conception
* Ductus arteriosus
* Embryo
* Fertilization
* Fetus
* Foramen Ovale
* HCG
* Implantation
* L/S ration
* Gestational age
* Vernix
* Zygote
* Placenta
* Quickening
* Surfactant
* Teratogens
* Umbilical Cord

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

Stages and Time Frames
* Ovum
* Zygote
* Morula
* Blastocyst
* Embryo
* Fetus

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

PRIMARY GERM LAYERS
* Ectoderm
* Mesoderm
* Endoderm

GESTATIONAL AGE
* Gestational age=Time since last menstrual period (LMP)
* EDC, EDD, EDB
* 266 Days after fertilization
* 280 Days after onset of LMP

Nagele’s Rule
Trimester
1st = week’s 1-13
2nd = week’s 14 - 26
3rd = week’s 27 and on (38-40 WEEKS)

STAGES OF DEVELOPMENT
FETAL MEMBRANES
* Amnion
* Chorion

Decidua capsularis
Decidua basalis
Developing placenta
Yolk sac
Amniotic cavity
Intrauterine cavity
Decidua vera
Mucus plug (operculum)
Chorion (blends with placenta)
Amnion (blends with umbilical cord)

Umbilical cord (funis)
Lacunae in decidua basalis filled with maternal blood
Intrauterine cavity
Decidua capsularis
Decidua vera

1 Month
Month 2
Month 3
Month 4
Month 5
Month 6
Month 7
Month 8
Month 9
Third Trimester
At 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

AMNIOTIC FLUID
* Clear, yellowish fluid surrounding the developing fetus.
* Average amount 1000 ml.
* Having < 300ml – Oligohydramnios, associated with fetal renal abnormalities.
* Having > 2 L – Hydramnios, associated with GI and other malformations.
* Protects Fetus
* Controls Temperature
* Supports Symmetrical Growth
* Prevents Adherence to amnion
* Allows Movement
* Source of oral fluid
* Acts as a excretion-collection repository

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.

PLACENTA
MOM
Baby
Produce protein hormones:
* Human chorionic gonadotrophin (HCG)- 8-10 days past conception, is basis for pregnancy test
* Progesterone
* Estrogen
* Human Placental Lactogen
* Sieve/filter – allows smaller particles through and holds back larger molecules. Passage of materials in either direction is effected by:
o Diffusion: gases, water, electrolytes
o Facilitated transfer: glucose, amino acids, minerals.
o Pinocytosis: movement of minute particle
* Mother transmits immunoglobulin G (IgG) to fetus providing limited passive immunity.
* Leakage: caused by membrane defect: may allow maternal and fetal blood mixing.

VIABILITY
RESPIRATORY SYSTEM
CARDIOVASCULAR SYSTEM
FETAL CIRCULATION
* HEPATIC SYSTEM
* MUSCULO-SKELETAL SYSTEM
GASTROINTESTINAL SYSTEM
RENAL SYSTEM
NEUROLOGICAL SYSTEM
ENDOCRINE SYSTEM
INTEGUMENTARY SYSTEM
IMMUNE SYSTEM
MULTIFETAL PREGNANCY
Teratogens
STAGES OF DEVELOPMENT

FETAL DEVELOPMENT.ppt