Differences Between Amniotic Fluid and Urine

Many pregnant women often have a hard time trying to distinguish between fluid that is urine and that which is amniotic fluid.  Some rely on the fluid’s scent to make the identity. Urine has a distinct scent and can be identified fairly easily, whereas amniotic fluids have a scent similar to sweet straw. The scent alone is not the only difference between amniotic fluid and urine.

Amniotic fluid is a liquid that is contained inside the amniotic sac of a pregnant woman.  Amniotic fluids are produced by a process called ‘exudation,’ when fluid is excreted through the skin of the fetus. Exudation begins at conception and continues to be produced through the beginning of the second trimester (up until the 14th week); a time when the skin of the fetus grows more mature in density’”a process called ‘keratinization.’ Creation of amniotic fluids continues at a lesser rate and volume throughout the remainder of the pregnancy until, at the end of the third trimester, the fluid is expelled from the body shortly before the birthing process begins.  Urine, by contrast, is the liquid waste by-product that is produced as the blood is filtered by the kidneys. Urine collects in the urinary bladder and is ultimately purged from the body by a process called ‘micturition.’

Functionally, amniotic fluid and urine differ greatly. The production of amniotic fluid is essential for a pregnant woman and for the healthy development of her baby. Toward the end of the second trimester and throughout the remainder of the pregnancy, amniotic fluids are ingested by the fetus. Amniotic fluid contains proteins, carbohydrates, lipids and electrolytes’”nutrients that are essential for normal fetal development.  Amniotic fluid is inhaled and exhaled by the fetus, thus providing vital oxygen for proper growth and development. It also acts as a cushion for the body of the fetus, allowing for easier movement and protection from injury inside the uterus.  Urine, by comparison, has no nutritional value and doesn’t function as protection. It is simply a soluble waste containing excess water, sugars and compounds that the body was not able to absorb.  Urine must be eliminated from the body because it contains toxins.

For pregnant women, amniotic fluids become an important part in determining the normalcy of the development of her fetus.  Certain complications can occur such as too little amniotic fluid (Oligohydramnios) or too much (Polyhydramnios or Hydramnios) which can lead to birth defects. During pregnancy, it is a common practice for an OBGYN to extract and examine amniotic fluids for abnormalities.  A pregnant woman’s urine may also be tested for blood sugar irregularities or urinary tract infections (UTI). Urine that is more clear (or without color) is considered healthier compared to urine that is yellowish or dark. If an infection is present, it should be treated immediately to prevent harm to the fetus.

Summary:
1. Urine is excreted from the kidney while amniotic fluid is produced inside the amniotic sac in the womb of a pregnant woman.
2. Amniotic fluid is inhaled and exhaled by the fetus, thus providing vital oxygen for proper growth and development of a fetus and must be retained in the body over the entire gestation period. By contrast, urine must be eliminated from the body because it contains toxins.
3. During pregnancy, it is a common practice for an OBGYN to extract and examine amniotic fluids for abnormalities.  The urine of a pregnant woman is commonly tested for urinary tract infections (UTI). If an infection is present, it should be treated immediately to prevent harm to the fetus.
4. Amniotic fluids contain proteins and other nutrients compared with urine which is composed of sugar, excess water and other compounds that pose harm if not expelled from the body.