OB Unit 3: Fetal Development

How is fetal development measured during pregnancy?

By the number of weeks after fertilization.

What months are included in the 1st trimester?

0-3 months

What months are included in the 2nd trimester?

3-6 months

What months are included in the 3rd trimester?

6-9 months and on

The first stage of fetal development, that has fertilization through the 2nd week…

Preembryonic stage

The second stage of fetal development, that is the end of the 2nd week through the 8th week…

Embryonic stage

The third and final stage of fetal development that goes from the end of the 8th week until birth…

Fetal stage

This stage, aka conception, begins with fertilization…

Pre-embryonic

The gametes (ovum or sperm cells) must each have a set of how many chromosomes?

23

When the gametes come together to form the zygote, how many chromosomes should be present in a healthy zygote?

46

(T/F) Sex determination and genetic information is determined at fertilization.

True

The mother is caring an XX zygote, what is the gender?

Female

The mother is caring an XY zygote, what is the gender?

Male

These twins occur when one fertilized egg splits and develops into two…

Identical twins

These twins develop when two separate eggs are fertilized by two different sperm…

Fraternal twins

When does implantation occur?

The pre-embryonic stage

Implantation occurs in the ______ _________, where a rich ______ _______ is available.

upper uterus; blood supply

This stage occurs when the zygote has multiplied and divided into an ________.

Embryonic stage; embryo

The embryonic stage begins and ends when?

It begins at day 15 after conception and continues through week 8.

What is the outermost membrane of the embryo?

Chorion

A thin protective membrane over the embryo that contains amniotic fluid that forms during the embryonic stage…

The amnion

These twins have: 2 chorionic sacs, 2 amniotic sacs, 2 placentas, 2 fetuses, and 2 umbilical cords.

Di-Di twins (fraternal twins)

These twins have: 1 chorionic sac, 2 amniotic sacs, 1 placenta, 2 fetuses, and 2 umbilical cords.

Mo-Di twins (Identical twins)

These twins have: 1 chorionic sac, 1 amniotic sac, 2 fetuses, and 2 umbilical cords…

Mo-Mo twins (Identical twins)

What kind of twins are the highest risk?

Mo-Mo twins

What stage of development starts at the end of the 8th week and goes until birth?

Fetal stage

What is the longest stage of prenatal development?

Fetal stage

What is the mature embryo called in the final stage of development?

Fetus

When does dramatic growth and refinement of all organ systems take place in development?

During the fetal period.

Approximately how much amniotic fluid is present at term?

1 liter

What 2 sources is amniotic fluid derived from?

Fluid transported from the maternal blood across the amnion and fetal urine.

What provides a cushions to protecta fetus from trauma?

Amniotic fluid

(T/F) Amniotic fluid helps maintain a constant body temp for the fetus.

True

(T/F) Amniotic fluid inhibits symmetric growth and development.

False

What component of amniotic fluid allows for fetal lung development?

Surfactant

What is the normal amniotic fluid index?

5-25 cm

Uteroplacental insufficiency, fetal renal abnormalities, and higher risk of surgical births and low-birth-weight infants can be caused by…

Oligohydramnios (too little amniotic fluid) < 500 mL at term

Maternal diabetes, neural tube defects, chromosomal deviations, and CNS malformations and/or GI tract that prevents normal swallowing of amniotic fluid by the fetus is associated with…

Polyhydramnios (too much amniotic fluid) > 2,000 mL at term

When does the placenta start to develop?

End of the 2nd week.

When and where does the umbilical cord start to develop?

Formed from the amnion at the end of the 2nd week.

What is the lifeline between the mother and the embryo?

The umbilical cord

The umbliical cord contains…

One large vein and two small arteries.

What surrounds the three blood vessels in the umbilical cord to prevent compression?

A specialized connective tissue, Wharton jelly.

Fetal circulation oxygenation occurs in the…

Placenta

Oxygenated blood is carried from the placenta to the fetus via the…

Umbilical vein

Two umbilical arteries carry unoxygenated blood back to the…

Placenta

What protects the fetus from immune attack by the mother?

Placenta

The placenta removes waste products from the fetus via the…

Umbilical artery

The placenta provides nutrients and oxygen to the growing baby via the…

Umbilical vein

The structure of the placenta begins to produce what that maintains the pregnancy at 12 weeks gestation?

Progesterone

Hormones like HCG, hPl, estrogen, progesterone, and relaxin are produced by…

The placenta

Fetal side of the placenta…

Shiny Shultz

Maternal side of the placenta…

Dirty Duncan

Signs of preganancy that the mother can perceive…

Presumptive

What are the least reliable indicators of pregnancy?

Presumptive changes

Amenorrhea, fatigue, n/v, urinary frequency, breast changes, and quickening (feelings of fluttering) are examples of…

Presumptive signs

Signs of pregnancy that can be detected on physical examination by a HCP…

Probable signs

Softening of the cervix…

Goodell sign

Softening of the lower uterine segment at 4-6 weeks…

Hegar sign

Bluish-purple coloration of the vaginal mucosa and cervix

Chadwick sign

Practice contractions of the uterus not usually felt until the 3rd trimester…

Braxton Hicks contractions

An examiner pushes against the woman’s cervix during a pelvic exam and feels a rebound from the floating fetus. This is known as…

Ballottement

Goodell sign, Hegar sign, Chadwich sign, changes in the shape and size of the uterus, Braxton Hicks contractions, Ballottement, pregnancy tests (blood and urine), and abdominal enlargement are all examples of…

Common probable signs of pregnancy.

The production of hCG can begin as early as…

The day of implantation

hCG can be detected as early as how many days before menses?

7 to 8 days

In a normal pregnancy, hCG levels _____ every ___ to ___ hours.

double; 48; 72

hCG levels peak approximately how many days after fertilization?

60 to 70

Multifetal pregnancy, ectopic pregnancy, hydatiform mole pregnancy, or genetic abnormality can be indicated by…

Higher levels of hCG

A miscarriage could be suggested by…

Lower than normal expected hCG levels

Confirmation that a fetus is growing in the uterus…

Postive signs

Visualizing the fetus by ultrasound, palpating for fetal movements, hearing a fetal heartbeat are examples of…

Positive signs of pregnancy

What are the only signs that can determine a pregnancy with 100% accuracy?

Positive signs