Changes of the Fetal Circulation at Birth
Changes soon after birth due to;
1. Cessation of placental blood flow
2. Initiation of respiration
Following changes occurs;
1. Closure of umbilical arteries
Functional closure; preventing blood drain out
2. Closure of umbilical vein
Umbilical vein forms ligamentum teres and ductus venosus become ligamentum venosum.
3. Closure of ductus arteriosus
Functional closure; 1-3 months and become ligamentum arteriosum (no useful function).
4. Closure of foramen ovale
Functional closure soon after birth, but anatomical closure about 1 year.
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