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Amniotic fluid
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Amniotic fluid is the water the baby floats in while in the uterus. The first thing it does is cushion: if the mother takes a blow to the abdomen, that fluid spreads the impact out instead of letting it hit the fetus at full force.
The surprising part is where it comes from: the baby makes it, out of its own urine and the secretions of its lungs. And it is cleared mainly in two ways: the fetus swallows it, and it is absorbed through the membranes that surround it. Between breathing, swallowing, and urinating, the same fluid leaves and re-enters through the fetus itself, and that is how the amount holds steady.
It is not water alone. It carries dissolved proteins, electrolytes, which are the body's salts, immunoglobulins, which are antibodies, and vitamins, and all of that comes from the mother.
That is why the amount matters so much: when the volume is abnormally high or abnormally low, it predicts worse outcomes for the fetus.
In brief
Amniotic fluid surrounds the embryo and fetus during development and cushions it against impacts.
Fetal urine and lung secretions make it; it is cleared mainly by fetal swallowing and intramembranous absorption.
Breathing, swallowing, and urinating are the three routes by which the fetus exchanges it.
The same fluid leaves and re-enters through the fetus itself.
It carries dissolved proteins, electrolytes, immunoglobulins, and vitamins that come from the mother.
An abnormally high or low volume predicts poor fetal outcomes.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingEmbryology, Amniotic Fluid, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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