Module 3: Fetal Growth and Development Flashcards

1
Q

What are 4 short term benefit of preconception care?

A
  • reducing the number of preterm births
  • decreasing the number of unintended pregnancies
  • lowering the risk of genetic disorders or environmental exposures
  • reducing maternal and neonatal mortality
  • improving maternal and child health outcomes
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2
Q

What is conception?

A
  • Egg meets sperm
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3
Q

What is mitosis?

A
  • Single cell divides into 2 identical daughter cells
  • cell first make copy of it’s DNA and then divides
  • facilitate growth and development or cell replacement
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4
Q

What is meiosis?

A
  • Single cell divides twice to produce four cells containing half the original amount of genetic info
  • replicating DNA and dividing twice
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5
Q

What is oogenesis?

A

-Produce one mature egg from primary ooycte
- begin fetal life in female

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6
Q

In oogenesis, which 2 hormones promote increase of oolyte after puberty?

A
  • follicle stimulating hormone FSH
  • luteinizing hormone LH
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7
Q

What is spermatogenesis?

A
  • Production of sperm from primordial germ cell
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8
Q

After male reach puberty what hormone releasing will begin the process of spermatogenesis in testes?

A
  • Androgen
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9
Q

When does the placenta begin to develop?

A
  • begins to develop in the first week of conception
  • begins to form at implantation
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10
Q

What are 4 functions of placenta?

A
  • placenta function as endocrine organ
  • acts as life support system
  • provide continuous supply of O2 + nutrients
  • remove CO2 + wastes
  • produce hormones to maintain pregnancy, facilitate fetal development, prepare women for birth + lactation
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11
Q

What are the 4 metabolic functions of placenta?

A
  • respiration
  • nutrition
  • excretion
  • storage
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12
Q

What 4 pregnancy hormones does placenta produce?

A
  • hCG: human chorionic gonadotropin: ensuring supply of estrogen and progesterone needed to maintain pregnancy
  • hPL: human placental lactogen: stimulate the maternal metabolism to supply nutrients needed for fetal growth
  • estrogen: stimulate uterine growth and uteroplacental blood flow
  • progesterone: maintain endometrium, stimulate maternal metabolism
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13
Q

What does “ placenta is not a barrier but a sieve” mean?

A
  • blood cannot pass through these cells membranes but many substances can like most drugs, infectious agents and maternal antibodies
  • acts more like a filter than a “barrier.”
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14
Q

What is the function of umbilical cord?

A
  • the umbilical cord transports the fetus blood to and from the placenta
  • arises from the central area of fetal side of placenta
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15
Q

How many veins/arteries does umbilical cord have?

A
  • one vein and two arteries
  • vein: transport oxygenated blood (O2) + nutrients from placenta to fetus
  • arteries: transports deoxygenated blood (CO2) + wastes from fetus to placenta
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16
Q

What is Wharton’s jelly and its function?

A
  • umbilical vein and arteries are surrounded by a gelatinous substance
  • it protects the cord vessels from compression
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17
Q

What is a nuchal cord?

A
  • when the umbilical cord is wrapped around the fetal neck
  • compression can occur if cord lies between fetal head and maternal pelvis or twisted around fetal body
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18
Q

What are the name of the 2 fetal membranes surround the developing embryo?

A
  • amnion: inner layer
  • chorion: outer layer
  • both begin to form at implantation
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19
Q

What two membranes form the “bag of waters” or fetal sac?

A
  • chorion and amnion
  • these two membranes adhere to form the fetal sac that contains amniotic fluid + developing embryo/fetus
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20
Q

What are 4 functions of the amniotic fluid?

A
  • helps to maintain a constant temperature for the embryo/fetus.
  • equalizes pressure and cushions fetus from trauma.
  • protects the embryo/fetus from infection.
  • distends the amniotic sac, allowing freedom of movement for the fetus.
  • keeps the embryo from becoming tangled with the membranes.
  • provides fluid for the fetus to swallow and “breathe.”
  • provides a repository for fetal wastes (urine).
  • in labor, as long as the membranes remain intact, protects placenta, umbilical cord, and baby from pressure of contractions and aids in the effacement and dilation of the cervix.
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21
Q

What is the normal amount of amniotic fluid in pregnancy?
What is oligohydramnios? Polyhydramnios?

A
  • volume of amniotic fluid: important factor in assessing fetal well-being throughout pregnancy
  • in normal pregnancy: 700 - 1100ml of amniotic fluid
  • oligohydramnios: less than 300ml in 3rd trimester
  • polyhydramnios: more than 2L of amniotic fluid
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22
Q

What is oligohydramnios associated with?

A
  • fetal renal anomalies
  • growth restriction
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23
Q

What are 2 malformations is polyhydramnios associated with?

A
  • neural tube defects
  • GI anomalies
  • other malformations
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24
Q

What are the 2 functions of yolk sac?

A
  • aids in transferring maternal nutrients + oxygen that have been diffused through the chorion to the embryo
  • hematopoiesis: formation of blood (occur in yolk sac)
  • blood cells and plasma are manufactured in the yolk sac
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25
Q

What colour is amniotic fluid?

A
  • clear, pale straw-coloured
  • not foul smelling
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26
Q

When does the embryo’s heart start beating?

A
  • The embryo’s heart starts beating by day 17 after conception
27
Q

What four hormones does the placenta produce and how do they function?

A
  • Human chorionic gonadotrophin (hCG): preserves the function of the corpus luteum, ensuring a continued supply of estrogen and progesterone needed to maintain pregnancy
  • Human placental lactogen (hPL): stimulates the maternal metabolism to supply nutrients for fetal growth, increases maternal resistance to insulin, and facilitates glucose transport across the placental membrane, stimulates breast development in preparation for lactation
  • Progesterone: maintains endometrium, decreases contractility of the uterus, stimulates development of breast alveoli, stimulates maternal metabolism
  • Estrogen: stimulates uterine growth and uteroplacental blood flow, causes proliferation of breast glandular tissue
28
Q

Describe the fetal and maternal sides of the placenta (colour/texture)?

A
  • The fetal side of the placenta is smooth, shiny, and bluish purple, with veins branching out from the umbilical cord, which is usually attached in the center to the edges of the placenta (like tree roots).
  • The maternal side of the placenta is red, rough textured, and looks a little like liver. It is made up of 15-20 cotyledons, or little sections, which are separated by furrows. It is sometimes gritty with grey or white calcium deposits.
29
Q

Does the placenta act as a “barrier” that stops harmful substances from getting to the fetus?

A
  • No,
  • most drugs and many viruses can pass through the placental membrane, which acts more like a filter than a “barrier.”
30
Q

If a pregnant woman’s blood circulation is compromised, what is the best position to ensure maximum blood flow to the placenta?

A
  • The best position to ensure maximum blood flow to the placenta is lying on her left side.
  • to increase and help with blood flow
31
Q

What is the name of the substance in the cord that prevents compression of the blood vessels?

A
  • Wharton’s jelly prevents compression of the blood vessels.
32
Q

In terms of growth and development, what does growth refers to?

A
  • Growth refers to the increasing size of the fetus and occurs throughout normal pregnancy. It is a result of two factors:
  • an increase in the number of fetal cells
  • an increase in the size of the fetal cells.
33
Q

What determines fetal lung maturity?

A
  • detection of pulmonary surfactant
  • the measure of Lecithin (critical alveolar surfactant) to Sphingomyelin (pulmonary phospholipid)
  • L/S ratio reaches 2:1 then infants lung considered to be mature
34
Q

What is meconium?

A
  • fetal waste products accumulate in intestine as dark green to black, tarry
  • this passes through rectum within 24hours of birth
35
Q

In terms of growth and development, what does development refers to?

A
  • Development refers to the functional and structural changes that occur in the fetal organ systems and occur throughout normal pregnancy.
  • Development of the fetus occurs in a cephalocaudal pattern, meaning development starts in the head and moves down towards the body and extremities.

Development is more complex than growth and includes:
- differentiation of the cells and tissues
- organization of cells and tissues into organ systems
- cell growth

36
Q

What are the 3 ways can gestational age be determined?

A
  • by assessing the date of the last menstrual period,
  • pregnancy test results, and/or
  • early ultrasound results
37
Q

What is organogenesis?

A
  • when a fetus’ organs and structures are formed and begin to function
  • Fetal growth and development are extremely rapid during the first 18 weeks after conception.
  • During this time, the embryo grows from a microscopic egg to a fully formed fetus weighing approximately 400 grams.
38
Q

What is symphysis fundal height (SFH) measuring?

A
  • fetal growth and assessed by measuring SFH
  • symphysis fundal height (SFH) should correspond approximately to the number of weeks that she is pregnant
  • when she is 32 weeks pregnant, her SFH should be 32 cm
39
Q

What are the three stages/period fetal development is divided into and how long does each last?

A
  • pre-embryonic period: conception to 14 days (0-2 weeks)
  • embryonic period: day 15 until 8 weeks of gestation
  • fetal period: at 9 weeks to 40 weeks or end of pregnancy
40
Q

What is teratogens?

A
  • substances or exposure that causes abnormal development
  • The embryonic stage lasts from day 15 until 8 weeks gestation.
  • During this critical period of organ development the embryo is most vulnerable to teratogens.
41
Q

What 3 substances/hazards can cross the placental barrier and harm embryo/fetal growth and development?

A
  • infections in pregnancy
  • drugs taken in pregnancy
  • environmental hazards
42
Q

Using Nagele’s rule, how is EDD or EDB calculated?

A
  • Nagele’s rule is applied by adding 9 months and 7 days to the first day of the last menstrual period (LMP)
  • OR you can also subtract 3 months and add 7 days
43
Q

What are 2 important reasons to determine estimated date of birth (EDB)?

A
  • scheduling of prenatal care + assessments,
  • assists in monitoring fetal growth
  • supports decision making if pregnancy complications occur
44
Q

Using Nägele’s rule estimate the date of delivery (EDB) for the following:
LMP: Jan 10, 2010
LMP: Jun 1, 2010
LMP: Mar 24, 2010

A
  • LMP: Jan 10, 2010 = EDB is Oct 17 2010
  • LMP: Jun 1, 2010 = EDB is Mar 8 2011
  • LMP: Mar 24, 2010 = EDB is Dec 31 2010
45
Q

How are infants classify?

A
  • Preterm (also known as premature): born after 20 weeks and before 37 weeks gestation (20 to 36+6)
  • Late preterm: born after 34 weeks and before 37 weeks of gestation (34 to 36+6)
  • Term: born between 37 weeks and 42 weeks of gestation
  • Post-term: born after the completion of week 42 of gestation (42 plus 1day)
46
Q

What are the 5 key features of fetal circulation?

A
  • Fetal oxygen needs are relatively low: fetal arterial pO2 is approximately 30 mm Hg, known as relative hypoxemia
  • The placenta is the organ of gas exchange
  • The fetal lungs are hypo-perfused and fluid filled: Because of low fetal P02, pulmonary arterioles are vasoconstricted which results in high resistance to blood flow
  • The fetal brain and heart have the highest oxygen needs
  • Right-to-left shunting occurs through the foramen ovale and ductus arteriosus: high pulmonary pressure diverts blood away from the lungs through the foramen ovale into the low pressure left atrium.
47
Q

What is meant by the expression “the fetus exists in a state of relative hypoxemia?”

A
  • “The fetus exists in a state of relative hypoxemia” refers to the low fetal pO2 , which, at 30, would cause tissue hypoxia in extrauterine life.
  • However, in utero, fetal oxygen needs are low, meaning that the pO2 of 30 is sufficient to meet the fetal tissue oxygen needs.
  • Therefore, the fetus does not suffer tissue hypoxia. Fetal oxygen needs are low because the maternal system is conducting many oxygen using functions such as metabolism, digestion, thermoregulation.
  • In addition, ventilation, which uses a great deal of energy and oxygen, is not occurring in the fetus.
  • Remember that the lungs are collapsed, fluid filled, and not functioning.
48
Q

What effects does the low fetal pO2 have on the pulmonary vessels and the ductus arteriosus?

A
  • The fetal pO2 of 30: results in pulmonary vasoconstriction + causes dilation of the ductus arteriosus.

Pulmonary vasoconstriction leads to
- increased pulmonary vascular resistance,
- high pulmonary artery pressure,
- right to left shunting, and
- pulmonary hypo-perfusion.

49
Q

The pressure gradients which exist between the right and left side of the fetal heart play a significant role in fetal circulation. Recalling that the right ventricle pumps blood to the lungs and that the left ventricle pumps blood to the placenta (via the umbilical arteries), try to determine which side of the heart is pumping against higher pressure.
“Gradient” means “quantitative difference.”

A
  • The right ventricle — because it is pumping blood to collapsed, fluid-filled, vasoconstricted lungs — is experiencing higher pressure than the left ventricle which is pumping blood to the low pressure placenta.
50
Q

Based on the pressure gradient which you determined in question 3, explain which direction blood will flow through the foramen ovale and the ductus arteriosus.

A
  • the foramen ovale shunts blood from the right side of heart to left side of heart
  • Blood will flow through both the foramen ovale and the ductus arteriosus in a right-to-left direction.
  • Blood always flows along the path of least resistance. In the fetus there is high pressure on the right side of the heart and low pressure on the left, making the path of least resistance from right to left.
  • At the foramen ovale blood flows from the right atrium to the left atrium.
  • At the ductus arteriosus blood flows from the pulmonary artery into the aorta.
51
Q

Based on your answer to question 4, explain how the pressure gradient and the direction of flow through the foramen ovale and the ductus arteriosus would enable the brain and heart to receive the most well-oxygenated blood in the fetal circulation. Remember that oxygenated blood arrives in the right atrium from the inferior vena cava and the umbilical vein. You may find it helpful to use a red pen or pencil to actually draw the oxygenated blood coming from the placenta to the brain and heart.

A

As soon as you have red, oxygenated blood entering the aorta
- that blood is available to the heart and brain
- because the coronary and carotid arteries are the first arteries to arise from the aorta.
- The foramen ovale gets well-oxygenated blood from the right atrium into the left atrium.
- From there this blood enters the left ventricle and then into the aorta.

Deoxygenated blood returns to the right heart from the head (via the superior vena cava),
- enters the right atrium, then the right ventricle, and then enters the pulmonary artery.
- This blood encounters the ductus arteriosus and shunts into the aorta, thereby deoxygenating the blood in the portion of the aorta below the ductus arteriosus.
- Fortunately the ductus arteriosus is situated below the carotid and coronary arteries, permitting the carotids and coronaries to avoid receiving this deoxygenated blood.
- They have already received well-oxygenated blood from the ascending aorta.
- In this way, the ductus arteriosus shunts blood into the aorta in order to bypass the lungs and deliver blood to the less vital organs (gut, liver, kidney, legs) and the placenta.
- It is situated in such a way that the heart and head do not receive any of this deoxygenated blood.

52
Q

What maternal infections are known to be associated with congenital malformations and disorders?

A

TORCH:
- Toxoplasmosis
- Other (gonorrhea, hepB, syphilis, varicella-zoster, parvovirus B19, HIV)
- Rubella
- Cytomegalovirus
- Herpes simple virus

53
Q

What are 4 environmental hazards to have adverse health outcomes with preconception and prenatal exposure?

A
  • PCBs
  • pesticides
  • solvents
  • air pollutants
  • lead
  • methyl mercury
54
Q

What percentile is considered appropriate for gestation age on growth curve chart? SGA? LGA?

A
  • Appropriate for gestational age: weight falls between the 10th and 90th percentile
  • Small for gestation age: infant weight who falls below the 10th percentile
  • Large for gestation age: infant weight who falls above the 90th percentile is considered LGA
55
Q

What is intrauterine growth restriction (IUGR)?

A
  • When a fetus does not meet the expected growth patterns
  • If fetal growth has been impaired throughout gestation, both cell number and cell size will be affected.
  • If fetal growth has been impaired for only the latter weeks or months of gestation, only cell size will be affected.
  • IUGR is described as either symmetrical or asymmetrical
56
Q

IUGR is described as either symmetrical or asymmetrical. What is the difference between symmetric growth restriction vs asymmetric growth restriction?

A

Symmetric Growth Restriction:
- conditions that occur in the early part of pregnancy generally result in overall growth restriction
- Symmetric growth restriction means the head circumference, length, and weight are all less than the 10th percentile on growth charts.
- Conditions that may lead to symmetric growth restriction include infections, teratogens, maternal undernutrition, heavy smoking, and chromosomal anomalies

Asymmetric Growth Restriction:
- Growth restriction that occurs in later stages of pregnancy
- Due to the ability of the fetus to shunt blood to vital organs such as the brain and heart, the growth of the body and head will not match (decreased growth to body in order to shunt blood to the brain)
- usually the result of maternal or placental issues such as hypertension, cardiovascular disease, or renal disease.

57
Q

What are some factors that may contribute to IUGR?

A
  • Multiple gestation
  • Poor maternal nutrition
  • Maternal heart disease
  • Maternal collagen disease
  • Maternal hypertension
  • Maternal infection
  • Maternal autoimmune disease
  • Family history of IUGR
  • Smoking
  • Recurrent antepartum hemorrhage
  • Fetal infections
  • Fetal cardiovascular anomalies
  • Drug and alcohol use
  • Fetal congenital anomalies
58
Q

If IUGR was suspected, what maternal assessment used to assess growth, would be less than expected?

A
  • SFH may be less than week’s gestation.
  • An Ultrasound would also reveal growth restriction
59
Q

What is a macrosomia infant?

A
  • when their estimated weight is more than the 90th percentile
  • macrosomic infant can be born pretermm, at term or post term
  • maternal diabetes is linked to macrosomia
60
Q

What weight is considered LBW? VLBW? ELBW?

A
  • low birth weight: <2500g
  • very low birth weight: <2000g
  • extremely low brith weight: <1000g
61
Q

In terms of growth and development, what does fetal growth refers to? What are the 2 factors?

A
  • increasing size of the fetus and occurs throughout normal pregnancy.

It is a result of two factors:
- an increase in the number of fetal cells
- an increase in the size of the fetal cells.

62
Q

In terms of growth and development, what does fetal development refers? What are the 3 factors are included?

A
  • refers to the functional and structural changes that occur in the fetal organ systems and occur throughout normal pregnancy
  • Development of the fetus occurs in a cephalocaudal pattern, meaning development starts in the head and moves down towards the body and extremities.

Development is more complex than growth and includes:
- the differentiation of the cells and tissues
- the organization of cells and tissues into organ systems
- cell growth

63
Q

What is the threshold viability in terms of gestation age?

A
  • the fetus is viable at 22 weeks
  • Infants who are born between 22-25 weeks are considered to be on the threshold of viability.
64
Q

What is fetal growth and development assessed/determined in relation to?

A
  • gestational age