Changes in the Fetal Circulation at Birth

Subject: Midwifery I (Theory)

Overview

The fetal circulation transforms right after birth due to the end of placental blood flow and the commencement of respiration. The vascular system undergoes the following modifications: Closure of the umbilical arteries, closure of the umbilical veins, closure of the ductus arteriosus, and closure of the foramen ovale. Within one or two hours of delivery, the cardiac output is determined to be around 500ml/min, and the heart rate ranges from 120-140 beats per minute. The nonfunctioning ductus arteriosus occluded and created ligament arteries. Similarly, nonfunctioning hypogastric arteries form a lateral umbilical signature.

The fetal circulation alters shortly after birth as a result of:

Cessation of the placental blood flow
Initiation of respiration

Changes in the Vascular System

Closure of the umbilical arteries:
The functional closure is practically instantaneous, preventing a small amount of fetal blood from draining out. The actual obliteration process takes roughly 2-3 months. The proximal and distal sections of the lateral umbilical ligaments remain accessible as superior vesical arteries.
Closure of the umbilical veins:
The obliteration happens later than the arteries, allowing the fetus to get a small amount of blood (80-100ml) from the placenta. The ductus venous collapse, as well as the venous pressure of the inferior venecava and the right atria, decline. The umbilical vein becomes the ligament teres after obliteration, while the ductus venous becomes the ligament venosum.
Closure of the ductus arteriosus:
The muscle wall of the ductus arteriosus contracts within a few hours of respiration, most likely in reaction to growing oxygen tension in the blood flowing through the duct. The effect of oxygen tension fluctuation on the ductus arteriosus is assumed to be mediated by prostaglandin activity, but functional closure of the ductus may occur rapidly after the initiation of pulmonary circulation. It takes about 1-3 months for the anatomical obliteration to develop ligament ateriosum.
Closure of the foramen ovale:
This is caused by an increase in left atrial pressure paired with a reduction in right atrial pressure. Functional closure happens shortly after birth, although anatomical closure takes roughly a year. During the first few days, the closure may be reversible, as seen by the baby's cyanotic appearance while crying.

Within one or two hours of delivery, the cardiac output is around 500ml/min, and the heart rate ranges from 120-140 beats per minute.

The occluded, nonfunctioning ductus arteriosus developed ligamentum arteries. Similarly, the lateral umbilical signature is formed by nonfunctioning hypogastric arteries.

References

Embryology. 27 01 2017. 07 03 2017 < http://www.embryology.ch/anglais/pcardio/umstellung01.html
Berkeley. http://mcb.berkeley.edu/courses/mcb135e/fetal.
Tuitui R. 2002, A textbook of Midwifery A (Antenatal), 3rd edition, Vidyarthi Pustak Bhandari (Publisher and Distributor), Bhotahity, Kathmandu
Wong, D.L., 1995, Whaley and Wongs, Nursing care of infants and Children, 5th edition, Mosby, St.louis, London, Philadelphia
Saxton, D.F., 2001, Mosby’s comprehensive review of the nursing 17th edition, Mosby Yearbook, St. Louis London, Philadelphia, Sydney.

Things to remember

The fetal circulation alters shortly after birth as a result of the end of placental blood flow and the commencement of respiration.
The vascular system undergoes the following changes:
Closure of the umbilical arteries, veins, and ductus arteriosus, as well as the closure of the foramen ovale.
Within one or two hours of delivery, the cardiac output is around 500ml/min, and the heart rate ranges from 120-140 beats per minute.
The occluded, nonfunctioning ductus arteriosus developed ligament arteries. Similarly, the lateral umbilical signature is formed by nonfunctioning hypogastric arteries.

Videos for Changes in the Fetal Circulation at Birth

Baby Circulation Right After Birth

Questions and Answers

Explain the changes in the fetal circulation at birth.

Changes in the fetal circulation at birth:

Soon after birth, the fetal circulation changes as a result of:

Stoppage of placental blood flow
Beginning of breathing

The vascular system undergoes the following changes:

Closure of the umbilical arteries: Functional closure almost immediately stops a small amount of fetal blood from draining out. The actual erasure process takes two to three months. The superior vesical arteries are still open in the lateral umbilical ligaments' distal and proximal portions.
Closure of the umbilical veins: The obliteration happens a little later than the arteries, allowing the fetus to receive a small amount more blood (80–100ml) from the placenta. The right atria as well as the inferior venecava's venous pressure and ductus venosus collapse. Following obliteration, the ductus venosum develops into the ligament venosum, and the umbilical vein creates the ligament teres.
Closure of the ductus arteriosus: After only a few hours of breathing, the muscle wall of the ductus arteriosus contracts, most likely in reaction to the blood's increased oxygen tension. Prostaglandin is hypothesized to act as a mediator between changes in oxygen tension and the ductus arteriosus, but functional closure of the ductus may take place quickly after the initiation of pulmonary circulation. The ligament ateriosum is formed after the anatomical obliteration, which takes about 1-3 months.
Closure of the foramen ovale: This results from an increase in left atrial pressure and a reduction in right atrial pressure. Anatomical closure takes roughly a year to occur, however functional closure happens shortly after birth. The baby's cyanotic appearance during crying is indication that the closure may be reversible during the first few days.

The cardiac output is determined to be roughly 500ml/min within one to two hours of birth, and the heart rate ranges between 120 and 140 beats per minute.