When this process completes around the 25th week,[2] the fluid is primarily absorbed by the fetal gut for the remainder of gestation.

[1] At first, amniotic fluid is mainly water with electrolytes, but by about the 12–14th week the liquid also contains proteins, carbohydrates, lipids and phospholipids, urea, and extracellular matrix (ECM) components including collagens and glycosaminoglycans, including hyaluronic acid and chondroitin sulfate, all of which aid in the growth of the fetus.

[5] Swallowed amniotic fluid (in later stages of development) creates urine and contributes to the formation of meconium.

The fetus, which develops within a fluid-filled amniotic sac, relies on the placenta for respiratory gas exchange rather than the lungs.

FBM are regulated differently in many respects than postnatal respiration, which results from the unique intrauterine environment.

Amniocentesis can be performed to obtain diagnostic genetic information, evaluate for intrauterine infection, or rarely, to assess for fetal lung maturity if early delivery is required.

Analysis of amniotic fluid can reveal many aspects of the baby's genetic health as well as the age and viability of the fetus.

These include contracture of the limbs, clubbing of the feet and hands, and also a life-threatening condition called hypoplastic lungs.

The obstetrician, gynaecologist or midwife should also routinely ultrasound the patient—this procedure will also give an indication of proper fetal growth and amniotic fluid development.

Oligohydramnios can be caused by infection, kidney dysfunction or malformation (since much of the late amniotic fluid volume is urine), procedures such as chorionic villus sampling (CVS), and preterm premature rupture of membranes (PPROM).

Oligohydramnios can sometimes be treated with bed rest, oral and intravenous hydration, antibiotics, steroids, and amnioinfusion.

[10][11] Recent studies show that amniotic fluid contains a considerable quantity of stem cells.

[18] These cells have demonstrated the ability to differentiate into a number of different cell-types, including brain, liver and bone.