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To answer a question myself, recently I've read that

Years and years ago, a long umbilical cord enabled a woman to grasp her baby after birth and run away from predators"

Update:

$Question:$ How umbilical cord is evolved and what's the reason behind it's elongation?

There is at least one position that supports this claim:

So why 61 cm? Umbilical cords of whales, porpoises, goats and other mammals are rela- tively shorter than the human cord. Walker and Rye of Cambridge surmised in the British Medical Journal in 1960 that prehistoric humans evolved length for protection. Nature's purpose was to allow the mother to pick up the newborn without disturbing the placenta. The event of breast feeding would then separate the placenta - an event which could attract predators. Having the fetus in tow would allow escape for mother and child.

(title: Silent Risk, auth.:Jason H. Collins). Well, right now I feel confused a bit...

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Of course.. thats a folk tale.. Anyways, you do know what umbilical cord is really for, don't you? –  WYSIWYG Aug 12 at 4:55
    
Ok, maybe I should ask another question - why is this so long? –  Lili Aug 12 at 5:07
    
+1 for the sense of humor; I haven't seen any question of such comical kind here recently. –  Greek Fellows Aug 12 at 5:21
    
:)... is it malice-exchange or science-exchange? :( could you, guys, please help me in either improving my answer or explaining why it's stupid? –  Lili Aug 12 at 5:28
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I do believe that this is not a HW question and has scope to be answered –  The Last Word Aug 12 at 5:52

1 Answer 1

up vote 6 down vote accepted

The woman running bit is obviously a myth but that is genius.. Other than that the length of the umbilical cord has been found to be highly variable depending on each individual. Characterizing it as just long would therefore not be right. According to Wikipedia,

The umbilical cord in a full term neonate is usually about 50 centimeters (20 in) long and about 2 centimeters (0.75 in) in diameter (reference).

Some complications during birth are

A number of abnormalities can affect the umbilical cord. The cord may be too long or too short. It may connect improperly to the placenta or become knotted or compressed (reference).

Why does it become too long has been associated with these factors.

Long umbilical cords, defined as total length over 70 cm, have been significantly associated with:

Maternal factors:

Systemic diseases. Delivery complications. Increased maternal age.

Fetal factors:

Non-reassuring fetal status during labor. Respiratory distress. Vertex presentation Cord entanglement. Fetal anomalies. Male sex. Increased birth weight.

Placental features:

Increased placental weight. Right-twisted cords. Hyper-coiled cords. True knots (reference).

In conclusion, length of the umbilical cord has an average as mentioned before and being too long or short can lead to complications during birth. Regarding evolution of the cord, you could read this discussion.

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