Amniotic Fluid, Amount & Composition, Physical Properties, Functions of Amniotic Fluid, Abnormalities of Amniotic Fluid, ( by GS India Nursing).

Definition:- The liquid that is around a baby when it is inside it’s mother’s body.

The Amniotic fluid is the protective liquid contained by the Amniotic sac of a gravid amniote. This fluid servers as a cushion for the growing fetus, but also servers to facilities the exchange of nutrients, water and biochemical products between mother and fetus.

Origin of Amniotic fluid:-

  • Amniotic fluid originate after 12th weeks of pregnancy.
  • The major contribution and amniotic fluid formation given by Placenta and umbilical cord.
  • The fetal contribution include fetal cell fetal urine fetal skin.
  • The fetal cell contribution is available upto 20 weeks.
  • After 20 weeks or 5 month the fetal structure completed.


Amniotic fluid volume is related to gestational age. It measures about 50 ml at 12 weeks 400 ml at 20 weeks and reaches its peak of 1 liter at 36-38 weeks. There after the amount diminishes, till at term it measures about 600-800 ml. If the Pregnancy continuous poster further reduction occurs to the extend of about 200 ml at 43 weeks.


The amount of amniotic fluid and health of fetus both are dependant upon maternal/ placental, supply.

  • 12 week– 50 ml.
  • 16 week– 100 ml.
  • 20 week– 400 ml.
  • 36 week– 800-1200 ml.
  • Term 40 week– 600-800 ml.
  • Post term 42 week– 200 ml.

Near term or post term the amount of amniotic fluid reduce due to-

  • Fetal swallow.
  • Fetal maturity.
  • Increase demand.

At term-

  • Fetal urine: 400-1200 ml.
  • Fetal swallow: 200-500 ml.
  • At the major contribution in amniotic fluid is given by fetal urine.
  • Pulmonary secretion also contribute in the formation.
  • Oligohydramnios Less than 200 ml Or 5 cm.
  • Polyhydramnios More than 2000 ml or 25 cm.

Composition of amniotic fluid:-

Amniotic fluid composition

The Amniotic fluid mainly contain water and also include urea, Uric acid, creatinine, amino acid, fatty acid, glucose, minerals, electrolytes, lanugo, vernix caseosa. The composition other than this indicate abnormality.

In the first half of pregnancy, the composition of the fluid is almost identical to a transudate of Plasma. What in late pregnancy the composition is very much altered mainly due to contamination of fetal urinary metabolites. The composition includes– 1. Water (98-99%) and 2. Solid (1-2%). The following are the solid constituents.

Physical properties:-

  • pH. 7.2
  • Clear, colourless, transparent, pale, turbid.
  • Amniotic fluid is isotonic in nature, during late pregnancy it become hypotonic.

Colour:- In early pregnancy, it is colourless but near term it becomes pale straw coloured due to the presence of exfoliated lanugo and epidermal cells from the fetal skin. It may look turbid due to the presence of vernix caseosa.

Abnormal colour reactions.

Green— meconium– fetal distress ( meconium aspirate syndrome).

Red— Hemorrhage.

Dark brown, ( Tobacco juice) — IUD ( intra uterine death).

Saffron ( Greenish-yellow) — post maturity.

Golden, ( Red-yellow) — Rh incompatibility ( hemolytic).

Functions of amniotic fluid:-

  • Protection, protection why infection external force or any shock. the principle is “Diversion’.
  • It promote growth and development by providing fetal movement and preventing adhesion.
  • Maintenance of temperature, amniotic fluid is originate from maternal plasma so temperature is same.
  • The nutritional value is minimum.
  • It flush the birth Canal during labour process.
  • Responsible for Cervical dilation.
  • Useful in diagnosis.
  • It also work as aborting agent.
  • Assessment of well beling, Fetal well being associated with pulmonary maturity (surfactant).

During pregnancy:-

1. It acts as a shock absorber, protecting the foetus from possible extraneous injury.

2. Maintenance and even temperature.

3. The fluid distends the amniotic sac and thereby allows 4 growth and free movement of the foetus and prevents adhesion between the fetal parts and amniotic sac.

4. It’s nutritive value is negligible because of small amount of protein and salt content however water supply to the foetus is quite adequate.

During labour:-

1. The amnion nd chorion or combined to from a hydrostatic. Wedge which helps in dilatation of the cervix.

2. During uterine contraction it prevents market interference with the placental circulation so long as the membranes remains intact.

3. It flushes the birth canal at the end of first stage of labour and by its aseptic and bactericidal action protects the fetus and prevents ascending infection to the utane cavity.

Abnormalities of amniotic fluid:-


It is typically diagnosed when the amniotic fluid index (AFI) is greater than 25cm. When amniotic fluid is more than 2000 ml at term.


  • Give endomethacine 25 mg orally to decrease urine output.
  • Ho raha women with symptomatic polyhydramnios may need Hospital admission.
  • Antacids may be prescribed to relieve heartburn and nausea.
  • No data support dietary restriction of salt and fluid.
  • Ine Sam cases amnion-reduction, also known as therapeutic amniocentesis, has been used in response to polyhydramnios.
  • Decrease amniotic fluid at term rate of 500 ml/hrs.
  • Should not be reduction 1liter to 1.5 liter.


When amniotic fluid is less than 200 ml at term then it is known as oligohydramnios.


  • Decrease fundal height (uterine size is much smaller than the period of Amenorrhea.
  • Fetal Malpresentation.
  • Undue prominence of fetal parts and reduced amount of amniotic fluid.
  • Less fetal movements.


In severe cases, oligohydramnios mein bhi treated with amnioinfusion during labour to prevent a umbilical cord compression.

Clinical importance:-

  • Study of the amniotic fluid provide Useful information about the well being and also maturity of the foetus.
  • Intra amniotic installation of chemical is used as method of induction of abortion.
  • Excess or less value of liquid any is assessed by amniotic fluid index (AFI). Maternal points: with ultrasound the largest vertical pocket in each quadrant is measured. The sum of the four measurement (cm) is the AFI. It is measured to diagnose the clinical condition of polyhydramios or oligohydramnios respectively.
  • Rachel of the membranes with drainage of liquor is a helpful method in induction of labour.

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By GS India Nursing…………!!

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