The fetal circulatory system differs from the adult system in that it facilitates an exchange of gases, nutrients, and waste between the fetus and mother via the placenta and umbilical cord. It includes three shunts - the ductus venosus, foramen ovale, and ductus arteriosus - that allow blood to bypass the liver and lungs and ensure oxygenated blood reaches the fetus. At birth, changes in pressure and the first breath cause the shunts to close as the circulatory system adapts to extrauterine life.

1. FETAL CIRCULATION
Mrs. Sumi Mathew
HOD,
OBG Nursing,
GCON, Jodhpur

2. definition
• The Fetal Circulation is defined as- The
blood circulation in the fetus or in other
words it is the circulatory system of
a fetus.
• The term usually encompasses the entire
feto-placental circulation, which
includes the umbilical cord and the
blood vessels within the placenta that
carry fetal blood.

3. CHARACTERTICS
• The fetal circulation system is distinctly different
from adult circulation,
• It facilitates the exchange of materials between
fetus and mother.
• It allows the fetus to receive oxygenated blood and
nutrients from maternal blood circulation and
elimination of CO2 & waste through the placenta,
• There are three bypasses or shunts in this
circulation which is specific to this circulation.

5. ANATOMY & PHYSIOLOGY
• Placenta - Site where exchange of
gases, nutrients and waste take places
with maternal circulation.

6. ANATOMY & PHYSIOLOGY – (conti.)
• Umbilical Cord – consists of 3 blood
vessels – 2 arteries and 1 vein

7. Bypasses -
• Ductus Venosus – carries oxygenated
blood from umbilical vein to inferior venacava
bypassing fetal liver
• Foramen Ovale – connects the right and
left. It pushes blood from right atrium to the
left atrium bypassing the pulmonary
circulation.
• Ductus Arteriosus - carries oxygenated
blood from pulmonary artery to aorta
bypassing fetal lung.

8. Flow Chart of Fetal Circulation

10. AT BIRTH -
• As the baby is born, the cardiovascular system
undergoes a quick, drastic change.
• With its first breath, the baby's pulmonary
vascular resistance substantially drops, which is
in response to the oxygen now present in the
lungs and the physical act of breathing.
• With the clamping of the umbilical cord after
birth, the systemic vascular resistance
increases helping the blood flow towards the
lungs.

11. AT BIRTH -
• The ductus arteriosus has a left-to-right flow
within 10 minutes. The smooth muscle in the
ductus arteriosus responds to the oxygen by
increasing calcium channel activity causing
constriction and ultimately closure of the shunt.
• The increased systemic resistance also raises
the pressure in the left atrium to be higher than
the right atrium, and this causes the foramen
ovale to close.

12. AT BIRTH -
• The ductus arteriosus becomes the
ligamentum arteriosum,
• The foramen ovale becomes the fossa
ovalis,
• The umbilical vein becomes the ligamentum
teres (round ligament).

13. SUMMARY
• The fetal circulatory system provides the fetus
with nutrients and oxygen, while also removing
waste products and carbon dioxide from fetal
circulation.
• The umbilical cord develops from the placenta
and is attached to the fetus. Oxygenated blood
from the mother in the placenta flows through
the umbilical vein and into the inferior vena
cava (IVC), bypassing the liver via the ductus

14. SUMMARY– (conti.)
• From the IVC, oxygenated blood travels to
the right atrium of the heart. There is greater
pressure in the right atrium compared to the
left atrium in fetal circulation; therefore most
of the blood is shunted from the right atrium
to the left atrium through an opening called
the foramen ovale.
• Once in the left atrium, blood travels through
the left ventricle into the aorta and the
systemic circulation.

15. SUMMARY– (conti.)
• The deoxygenated blood travels back to the
placenta via the umbilical arteries to be
oxygenated by the mother.
• Additionally, some oxygenated blood in the
right atrium can also enter the right ventricle
and then the pulmonary artery.

16. SUMMARY– (conti.)
• Because there is high resistance to blood flow
in the lungs, the blood is shunted from the
pulmonary artery into the aorta via the ductus
arteriosus, hence bypassing the lungs.
• Blood then enters the systemic circulation, and
the deoxygenated blood is recycled back to the
mother via the umbilical arteries.