Ch 12 Conception And Fetal Development Flashcards
Implantation
Occurs between 6-10 days after fertilization
Bleeding or spotting may occur
Fetal membranes
Chorion
Amnion
Chromosomes
XX female XY male
Amniotic fluid purpose
Space for movement and protection Thermo regulation Supplies fetus with nutrients and fluid Can be tested for genetic disorders Prevents amnion (layer of the amniotic sac) from sticking to fetus Prevents umbilical cord compression
Amniotic fluid amount
800 to 1200 ml present at birth
Polyhydramnios
Too much amniotic fluid, more that 2000 ml
Could indicate GI malformation of the fetus
Oligohydramnios
Not enough amniotic fluid
Less than 300 ml
Associated with renal malformations
Umbilical cord is protected by
Wharton’s jelly
Vessels in umbilical cord
2 arteries 1 vein
Arteries away from fetus
Vein carries oxygen rich blood to fetus
Organs in the fetus originally develop where?
In the umbilical cord because the abdomen is so small in the beginning
Placenta
Considered an endocrine gland
Secretes hcg, hpl, estrogen, progesterone
Hcg detected how long after conception
10 days (in maternal serum)
Hpl
Human placental lactogen, also known as chorionic somatotropin
Similar to human growth hormone, needed for fetal development
Stimulates maternal metabolism to supply nutrients needed for fetal growth
Placental development
Develops during week three and is fully functional by week 12
Other placenta jobs
Regulates transport of gases, nutrients, and waste
Dirty Duncan
Maternal side
Shiny Schultz
Fetal side
Pre-embryonic stage
Conception to day 14
Rapid cell division
Primary germ layers and the embryonic membranes form
The primary germ layers are the basis for all tissues and all organs to grow from
Embryonic stage
Day 15 to week eight
Structures of major organs are complete and organ systems are functioning
Big risk for teratogens
Most deformities will occur between weeks three and week eight
Examples of teratogens
Radiation, lead, chemotherapy agents, cmv (a virus), MMR vaccine (avoid pregnancy 28 days after vaccine), rubella
Month one
Hematopoiesis (formation of blood cells)week three
Day 25 the heart is beating
Fourth week the GI system is functioning
In the first month the liver, thyroid, bones, muscles and epidermis are forming
Neural tube (start of central nervous system)
At the end of this month the fetus is half an inch long and less than 1 oz
First functioning organ system
Cardiac system
Month two
Ears, ankles, wrists are developed The eyelids are still shut Hematopoesis continues By the fifth week is swallowing and voiding The brain has five lobes Pancreas and nerve fibers are developing At the end of month two fetus is 1 in long and less than 1 oz Rh factor is developed by about 6 weeks
Month three
Baby has fingers and toes, soft nails, baby teeth
Can hear fetal heart rate with Doppler
Renal function
Baby starting to move
Adrenal cortex is producing hormones
Reproductive parts begin to develop and sex characteristics begin to develop (may not be visualized)
Lanugo and vernix
By the end of month three baby is 2 1/2 in long and greater than 1 oz
Second trimester
Baby is viable at the end of trimester
A period of Rapid fetal development
Month four
Baby moves kicks and swallows Has handprints at 16 weeks Is forming meconium Placenta is fully formed and functioning Six to seven inches and 5 oz
Month 5
Sleep and wake intervals
Week 20 is producing insulin
Is actively felt by Mom
8 to 12 in and 1/2 to 1 lb
Month 6
Lenugo all over Eyes are open 11 to 14 in and one to one and a half pounds 28 cm 24 weeks means viability
Third trimester
A period of refinement and growth
Month 7
Eyes open and close Responds to light and sound Begins to store fat Testes to send into scrotum 15 in and 3 lb
Month 8
Rapid brain growth Skull is soft and flexible Mature GI system Baby is storing iron 18 in and 5 lb
Month 9
Brain is a quarter the size of an adult
Gains 1/4 to 1/2 lb per week
6 to 9 lb and 19 to 21 in
Fetal circulation structures involved
Heart
Placenta
Fetal tissue
Three purposes of fetal circulation
Increased blood flow to the Head and the heart
Decreased blood flow to the fetal lungs
And direct blood to the placenta
In utero the fetus…
Shunts blood flow to the lungs
The ductus arteriosus bypasses the lungs
Low hr in utero means
Low fetal circulation
Increase heart rate by turning mom on her side
After birth when baby starts to breathe…
Shunts no longer needed, transition to extra uterine life
Surfactant
20-24 weeks, stabilizes alveoli
Keeps alveoli from sticking to itself and collapsing
Alveoli aren’t mature until…
Weeks 35-37
L/S ratio (lecithin/sphingomyelin)
2:1 ratio indicates lung maturity
Maternal use of steroids can stimulate production. A mom in early labor might receive steroids to help lungs mature.
How to diagnose multifetal pregnancy
Polyhydramnios (too much fluid)
Asynchronous fetal heart rate (fhr)
Ultrasound evidence
Likelihood of multifetal pregnancy if…
History of dizygotic twins in female history
Use of fertility drugs
Monozygotic
Fertilization of a single ovum by one sperm
Identical
history of disygotic twins in female history and use of fertility drugs will increase the likelihood
Congenital malformations are more likely
Dizygotic
Fertilization of two ova by two sperm
Fraternal twins or non-identical
