Pregnancy: what is amniotic fluid used for?

What is amniotic fluid?

Amniotic fluid is a light yellow fluid that appears in the amniotic sac that protects the baby in the womb on the 12 days after follow design. This fluid is vital for the development of a healthy fetus.

At the start of pregnancy, amniotic fluid comes from the mother’s body. Little by little, it will be replaced by liquid secreted by the baby’s kidneys, that is to say his urine.
It also contains nutrients, hormones and antibodies to fight possible infections.
As it grows, the baby breathes and swallows this amniotic fluid. Also, the doctor can diagnose, based on the volume of amniotic fluid, if the baby has a swallowing problem.

What is amniotic fluid used for?

To protect the fetus from external pressures (it acts as a natural airbag).
To maintain a constant temperature and to insulate the baby from heat and cold.
To develop the digestive and respiratory systems by breathing and swallowing amniotic fluid.
To prevent certain parts of the body (such as fingers or toes) from growing by sticking together.

In an uncomplicated pregnancy, the volume of amniotic fluid reaches its highest (800 ml on average) between the 34th and the 36th week. This volume will decrease as let the birth approach from the 38th week of amenorrhea.

Sometimes the amniotic fluid is too abundant (this is the hydramnios), sometimes it is lacking (this is the oligo-amnion). But rest assured, these situations are rare.

What is hydramnios?

As we have seen, amniotic fluid is essentially the fluid secreted by the baby’s kidneys. But it happens (in one in every 100 pregnancies) that the volume is in excess, which leads to a marked increase in the abdominal volume of the mother-to-be.The main cause of this increase in volume is gestational diabetes. But poly-hydramnios can also be caused by certain fetal disorders (such as esophageal atresia or a pulmonary abnormality) that will require treatment at birth.

What is oligo-amnion?

The diagnosis of oligo-amnion is suggested when the height of the uterus is low for the term. When it is confirmed by ultrasound, the doctor looks for the cause, and checks if there is no premature rupture of the membranes which would cause a discharge of the liquid (which the mother can confuse with a urinary leak).

Trace amnion can also intervene in women who suffer high blood pressure, diabetes, lupus or who expect twins.

Diagnosis is essential because if the water bag is opened, there is a risk of infection of the fetus. In addition, if the amniotic fluid is lacking, the baby’s joints may become blocked (this is arthrogryposis) and the development of the bronchi and pulmonary alveoli may be more or less compromised.

More informations : The ledger of my pregnancy, by Experts of the National College of Gynecologists and Obstetricians, Eyrolles editions

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