NSPN 7100 CORRECT FINALS QUESTIONS AND
ANSWERS SET A+
✔✔What is gestational age? - ✔✔is determined by assessing the date of the last
menstrual period, pregnancy test results, and/or early ultrasound results.
✔✔What is organogenesis? - ✔✔-fetal growth and development rapid during first 18
wks
-when a fetus organs and structures are formed and begin to function
✔✔What is symphysis fundal height (SFH)? - ✔✔-measures fetal growth
-corresponds to the number of weeks to number of cm
-example woman is 32 wks, SFH should be 32 cm
-recorded on antenatal record
✔✔Fetal development is divided into three stages. Describe them. - ✔✔0-2 weeks
Pre-embryonic
Starts at conception and continues for the first 14 days of development, when
implantation has usually occurred.
The fertilized egg differentiates into different specialized cells; travels down fallopian
tube and implants in the uterus
2-8 weeks
Embryonic
Begins 14 days after conception and continues until the end of the eighth week after
conception when the embryo becomes a fetus.
,Rapid growth and development; organogenesis occurs and most organs begin to
function; the embryo's heart is beating; its head is disproportionately large, due to rapid
brain development; arms and legs have joints, and fingers are distinct.
9-40 weeks
Fetal
Starts at the beginning of the ninth week after conception and continues until "term," or
the end of the pregnancy.
By week 14, the placenta is fully formed and functioning; fetal organs continue to
develop; the fetus is viable at 22 weeks; significant increase in size (weight) in last 10-
12 weeks of pregnancy (28-40 weeks).
✔✔When is a fetus considered viable? - ✔✔Between 22-25 weeks
✔✔How is gestational age measured? - ✔✔-using the Nagele's rule
-Nagele's rule is applied by adding 9 months and 7 days to the first day of the last
menstrual period (you can also subtract 3 months and add 7 days).
✔✔Calculate EDD:
LMP Jan 10, 2010 - ✔✔Oct, 17, 2010
✔✔Calculate EDD:
LMP June 1, 2010 - ✔✔Mar 8, 2011
✔✔Calculate EDD:
LMP Mar 24, 2010 - ✔✔Dec 31, 2010
✔✔Gestational age is used to classify infants:
Describe the classifications. - ✔✔•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)
•Post-dates: This term is often used interchangeably with post-term. (In practice you will
often notice post-dates inductions occurring at 41 weeks. We will explore induction of
labour further in module 5B)
✔✔Fetal circulation has 5 characteristics. Describe them. - ✔✔1.Fetal oxygen needs
are relatively low. The fetus has low oxygen needs because many oxygen using
activities such as respiration, thermoregulation, and digestion are carried out in the
maternal system via the placenta. The fetal arterial pO2 is approximately 30 mm Hg.
,This is known as relative hypoxemia, which means that although 30 would be indicative
of tissue hypoxia in extrauterine conditions, because of the low oxygen needs of the
fetus in utero, there is no fetal tissue hypoxia. The low fetal pO2 causes pulmonary
vasoconstriction, which serves to keep the lungs hypoperfused. The low fetal pO2 is
also responsible for keeping the ductus arteriosus patent.
2.The placenta is the organ of gas exchange. Blood must flow from the fetus to the
placenta and from the placenta to the fetus through the umbilical arteries and veins. The
umbilical arteries carry deoxygenated blood to the placenta; the umbilical vein carries
oxygenated blood to the fetus. The placenta is a low pressure organ which offers very
little resistance to blood flow. This contributes to the fetus' low systemic blood pressure
and low left ventricular pressure.
3.The fetal lungs are hypo-perfused and fluid filled. Because they are not being utilized
for gas exchange the lungs receive only about 10% of the fetal cardiac output; just
enough to allow them to grow and develop. The fetal lungs are, as a result, hypo-
perfused. Because of low fetal P02, pulmonary arterioles are vasoconstricted which
results in high resistance to blood flow. Because gas exchange does not occur in fetal
circulation, the alveoli are filled with fluid, rather than with air.
4.The fetal brain and heart have the highest oxygen needs. Both of these organs have
high oxygen requirements. Because the fetal pO2 is relatively low (owing to the low
oxygen needs of other organs), fetal circ
✔✔What does it mean "the fetus exists in a state of relative hypoxemia"? - ✔✔"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.
✔✔What effects does the low fetal PO2 have on pulmonary vessels and ductus
arteriosus? - ✔✔The fetal pO2 of 30 results in pulmonary vasoconstriction and causes
dilation of the ductus arteriosus.
Pulmonary vasoconstriction leads to increased pulmonary vascular resistance, high
pulmonary artery pressure, right to left shunting, and pulmonary hypoperfusion.
✔✔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." - ✔✔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.
✔✔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. -
✔✔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.
✔✔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. - ✔✔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.
✔✔What is a teratogen? - ✔✔A teratogen is a substance that causes structural and/or
functional harm to the fetus. The impact of the teratogen is determined by the
gestational age at which the exposure occurred, the amount and length of exposure,
and the genotype of the embryo/fetus. "Known human teratogens are certain drugs and
chemicals, infections, exposure to radiation, and certain maternal conditions such as
diabetes and phenylketonuria (PKU)".
✔✔What drug given to pregnant women caused major health anomalies? -
✔✔diethylstilbestrol
ANSWERS SET A+
✔✔What is gestational age? - ✔✔is determined by assessing the date of the last
menstrual period, pregnancy test results, and/or early ultrasound results.
✔✔What is organogenesis? - ✔✔-fetal growth and development rapid during first 18
wks
-when a fetus organs and structures are formed and begin to function
✔✔What is symphysis fundal height (SFH)? - ✔✔-measures fetal growth
-corresponds to the number of weeks to number of cm
-example woman is 32 wks, SFH should be 32 cm
-recorded on antenatal record
✔✔Fetal development is divided into three stages. Describe them. - ✔✔0-2 weeks
Pre-embryonic
Starts at conception and continues for the first 14 days of development, when
implantation has usually occurred.
The fertilized egg differentiates into different specialized cells; travels down fallopian
tube and implants in the uterus
2-8 weeks
Embryonic
Begins 14 days after conception and continues until the end of the eighth week after
conception when the embryo becomes a fetus.
,Rapid growth and development; organogenesis occurs and most organs begin to
function; the embryo's heart is beating; its head is disproportionately large, due to rapid
brain development; arms and legs have joints, and fingers are distinct.
9-40 weeks
Fetal
Starts at the beginning of the ninth week after conception and continues until "term," or
the end of the pregnancy.
By week 14, the placenta is fully formed and functioning; fetal organs continue to
develop; the fetus is viable at 22 weeks; significant increase in size (weight) in last 10-
12 weeks of pregnancy (28-40 weeks).
✔✔When is a fetus considered viable? - ✔✔Between 22-25 weeks
✔✔How is gestational age measured? - ✔✔-using the Nagele's rule
-Nagele's rule is applied by adding 9 months and 7 days to the first day of the last
menstrual period (you can also subtract 3 months and add 7 days).
✔✔Calculate EDD:
LMP Jan 10, 2010 - ✔✔Oct, 17, 2010
✔✔Calculate EDD:
LMP June 1, 2010 - ✔✔Mar 8, 2011
✔✔Calculate EDD:
LMP Mar 24, 2010 - ✔✔Dec 31, 2010
✔✔Gestational age is used to classify infants:
Describe the classifications. - ✔✔•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)
•Post-dates: This term is often used interchangeably with post-term. (In practice you will
often notice post-dates inductions occurring at 41 weeks. We will explore induction of
labour further in module 5B)
✔✔Fetal circulation has 5 characteristics. Describe them. - ✔✔1.Fetal oxygen needs
are relatively low. The fetus has low oxygen needs because many oxygen using
activities such as respiration, thermoregulation, and digestion are carried out in the
maternal system via the placenta. The fetal arterial pO2 is approximately 30 mm Hg.
,This is known as relative hypoxemia, which means that although 30 would be indicative
of tissue hypoxia in extrauterine conditions, because of the low oxygen needs of the
fetus in utero, there is no fetal tissue hypoxia. The low fetal pO2 causes pulmonary
vasoconstriction, which serves to keep the lungs hypoperfused. The low fetal pO2 is
also responsible for keeping the ductus arteriosus patent.
2.The placenta is the organ of gas exchange. Blood must flow from the fetus to the
placenta and from the placenta to the fetus through the umbilical arteries and veins. The
umbilical arteries carry deoxygenated blood to the placenta; the umbilical vein carries
oxygenated blood to the fetus. The placenta is a low pressure organ which offers very
little resistance to blood flow. This contributes to the fetus' low systemic blood pressure
and low left ventricular pressure.
3.The fetal lungs are hypo-perfused and fluid filled. Because they are not being utilized
for gas exchange the lungs receive only about 10% of the fetal cardiac output; just
enough to allow them to grow and develop. The fetal lungs are, as a result, hypo-
perfused. Because of low fetal P02, pulmonary arterioles are vasoconstricted which
results in high resistance to blood flow. Because gas exchange does not occur in fetal
circulation, the alveoli are filled with fluid, rather than with air.
4.The fetal brain and heart have the highest oxygen needs. Both of these organs have
high oxygen requirements. Because the fetal pO2 is relatively low (owing to the low
oxygen needs of other organs), fetal circ
✔✔What does it mean "the fetus exists in a state of relative hypoxemia"? - ✔✔"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.
✔✔What effects does the low fetal PO2 have on pulmonary vessels and ductus
arteriosus? - ✔✔The fetal pO2 of 30 results in pulmonary vasoconstriction and causes
dilation of the ductus arteriosus.
Pulmonary vasoconstriction leads to increased pulmonary vascular resistance, high
pulmonary artery pressure, right to left shunting, and pulmonary hypoperfusion.
✔✔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." - ✔✔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.
✔✔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. -
✔✔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.
✔✔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. - ✔✔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.
✔✔What is a teratogen? - ✔✔A teratogen is a substance that causes structural and/or
functional harm to the fetus. The impact of the teratogen is determined by the
gestational age at which the exposure occurred, the amount and length of exposure,
and the genotype of the embryo/fetus. "Known human teratogens are certain drugs and
chemicals, infections, exposure to radiation, and certain maternal conditions such as
diabetes and phenylketonuria (PKU)".
✔✔What drug given to pregnant women caused major health anomalies? -
✔✔diethylstilbestrol
