Prenatal Development Flashcards
What are the 3 prenatal developmental stages?
zygote (fertilization - 2 wks), embryo (3 -8 wks), fetus (9-38 wks)
Define zygote and the zygote period.
fertilized egg; begins at fertilization & ends when ovum implants itself in uterus wall (2 week process)
Define embryo and embryo period.
term given to zygote once it is completely embedded in uterine wall; critical time of development of 3rd - 8th week; development of heart, cns, eyes, limbs, ears, teeth, palate and external genitalia occurs
Define the Placenta.
link between the mother & fetus - allows nutrients to pass to fetus; allows waste material to be removed
Define the umbilical cord.
attached to placenta at one end & to the child on the other end (20 inches in length)
How big is the embryo by the end of the 8 week period?
1.5-2 inches in length, .66 weights, all organs now present
Describe the fetus period.
End of 2nd month - birth; head and internal organs develop first, limbs and digits last.
Define proximodistal growth.
Growing near to far.
Define cephalocaudal growth.
Growing head to tail.
Define Teratogens.
external factors causing malformations or physical defects in fetus.
Give examples of teratogens.
prescription and non-description drugs (1 dose lasts 48 hours in adult/ 4-5 days in fetus), chemicals (mercury, hydrocarbons, lead), nicotine, caffeine, alcohol
Describe Fetal Alcohol Syndrome and Disorder.
facial malformations, retarded physical growth, impaired language development, attention deficits, learning impairment, mental retardation (FAS is leading cause of MR in the US); FAS - 2-7 per 1K, FASD 20-50 per 1K
Give examples of diseases that affect prenatal development.
German measles (Rubella), diabetes, herpes, AIDS: risk of transmission from mother to fetus is 35-60%; transmitted through placenta or the virus being present in the lining of brith canal.
Define an abortion.
fetus born before 20th week, weighing less than 500 grams/1 lb
Define an immature birth.
fetus born between 20th -28th week weighing 1-2 lbs; some now survive
Define a premature birth.
fetus born 29th-36th week weighing 2-5.5 lbs; many now survive
Define a mature birth.
fetus born 37-42 week weighing 5.5 lbs +, anything past this is considered a post-mature birth
Describe the first stage of labor.
longest stage; may be 12-24 hours; contractions of low intensity, cervix begins to dilate
Describe the second stage of labor.
delivery; starts with baby’s head at opening of cervix, ends with birth of baby
Describe the third stage of labor.
Afterbirth; placenta and other membranes are expelled.
Compare natural birth to Cesarean birth.
3 stages are bypassed for a C-section; 32% of all births; rates have increased 60% from ‘96-2009
What is the APGAR scale?
evaluation of heart rate, respiratory, muscle tone, color, reflex irritability; done at 1,5, & 10 minutes; Max score is 10, average is 7, if score is 4 or less, special care is needed
