Amniotic fluid is the fluid that surrounds the fetus inside the uterus during pregnancy and that is contained in the amniotic sac or amnion. The amnion (amnionfrom the Greek ἀμνίον, 'membrane of the fetus') is the closed sac that envelops and protects the embryo and then the fetus, and that is formed as an extraembryonic membrane.
The amniotic fluid is an aqueous fluid fluid, clear and slightly yellowish that allows to move within the wall of the uterus without the walls of the uterus too closely fit your body. It also provides hydraulic lift. The amniotic fluid is mainly produced by the mother until 17 weeks of gestation.
The amniotic sac grows and begins to fill, mainly with water two weeks after fertilization. After ten weeks the liquid contains proteins, carbohydrates, lipids and phospholipids, urea and electrolytes, all of which help the development of the fetus.
In the last stages of pregnancy, most of the amniotic fluid is made up of fetal urine. The amniotic fluid circulates constantly as the baby swallows it and "inhales" it and then releases it and "exhales" through the urine.
This is normal and does not pose a risk, but if amniotic fluid begins to have meconium, the baby's first feces (what is known as "having stained water"), meconium aspiration syndrome can occur, a respiratory disorder caused by the inhalation of meconium from the amniotic fluid within the bronchial tree.
There may also be floating in the amniotic fluid remnants of vernix caseosa or sebaceous stub, which protect the baby's delicate skin from the irritating effects of amniotic fluid and dehydration; and remains of lanugo or villi that protect the baby's body.
Observation and control of amniotic fluid
The amount of amniotic fluid is greater at approximately 34 weeks of pregnancy, when it reaches an average of 800 milliliters. Approximately 600 milliliters of amniotic fluid surround the baby at term (40 weeks gestation). Ultrasound of the last stage of pregnancy controls the amount of amniotic fluid, in case there have been undetected losses.
At the time of delivery, an amnioscopy can also be performed, that is, a test that is performed by the introduction, vaginally, of a metal tube provided with a light that allows illuminate the membranes of the amniotic bag to assess the color of the liquid, in case there is meconium or other problems that put the baby's health at risk.
But its results are not safe, so it is not recommended to do amnioscopy just in cases of risk.
It is important observe the color of the amniotic fluid when water breaks naturally, or if an artificial membrane rupture is made, although this maneuver does not have to be performed routinely; however, it remains one of the most frequent unnecessary interventions in childbirth. The liquid should be light colored, since if it is dyed a greenish color it is a symptom that it contains traces of meconium.
Functions of amniotic fluid
As for its functions, it is important that it be in good condition and in sufficient quantity because the amniotic fluid helps:
- The fetus to move in the uterus, which allows proper bone growth.
- To the proper development of the lungs.
- To maintain a relatively constant temperature around the baby, thus protecting it from heat loss.
- To protect the baby from external injuries by damping blows or sudden movements.
Amniotic fluid outlet
Amniotic fluid can leave the sac due to a loss or fissure in the amniotic sac or due to water rupture.
Losses of amniotic fluid They are detected because the underwear is wetted with an aqueous liquid that flows slowly but steadily, or when making certain movements. It differs from vaginal discharge because it is filamentous. If it occurs towards the end of pregnancy it may be water breakage.
It can also happen after an amniocentesis (that's why you have to take a special observation, since there is a risk of infection) or in women with a clinical history of premature rupture of the bag.
Water breakage It occurs when the amniotic sac releases its contents, what is known as "water ropmer" or "source break". When this happens during childbirth at the end of pregnancy, it is called "spontaneous rupture of membranes." If the rupture precedes the end of labor, it is called "premature rupture of membranes."
In the investigation of new sources of stem cells it has been proven that the amniotic fluid contains them. Recent work by a group of researchers led by Anthony Atala of Wake Forest University and a Harvard University team has discovered that amniotic fluid is a source of abundant non-embryonic stem cells.
Soon we will return with other peculiarities about the amniotic fluid, that fluid that surrounds and protects the baby in the womb during pregnancy, which is its protective environment for so many weeks.
