Normal amniotic fluid

The unborn child develops in the mother's body in a special bladder called the amnion. Its main task is to create ideal conditions for development for the child and produce amniotic fluid.

What is amniotic fluid

The fluid filling the amniotic sac is very important for the development of the child. It is the baby's first habitat and provides him with comfort and protection. Thanks to amniotic fluid, the baby is always in an environment with temperature+37 degrees. The fluid inside the amnion protects the baby from attack by microorganisms and other negative influences from the environment.

The production of fluid inside the amnion is constant, but its amount varies depending on the duration of pregnancy. The longer the period, the more fetal fluid surrounds the baby. The maximum amount of fluid inside the amnion is usually observed at 36 weeks of pregnancy. Basically, its volume reaches up to one and a half liters. By the day of birth, its amount decreases due to the body’s preparation for childbirth.

During pregnancy, not only the volume of fluid surrounding the fetus changes, but also its composition. It contains everything that is required to nourish the baby and provide him with oxygen. Also in the amniotic fluid there are substances coming from the mother’s blood, the baby’s urine and products of the processing of the baby’s sebaceous glands.

The fetal fluid performs very important tasks:

• It ensures material metabolism, providing the crumbs necessary for life. In response, the child releases waste products into the amniotic fluid, which are then excreted through the maternal excretory system.
• Protects the baby from physical damage, does not allow tissues to grow together and does not allow the umbilical cord to be compressed. Thanks to the fluid inside the amnion, the baby can freely move and develop intensively.
• The sterility of the aqueous environment of the fetal bladder protects the baby from infection.
• Amniotic water is constantly renewed, maintaining the optimal chemical composition for the child.
• The role of water is great and in the process childbirth. They help open the cervix and help the baby pass through the birth canal.
• Based on the appearance and chemical composition of the fluid in the amnion cavity, one can draw a conclusion about the condition of the fetus, determine the sex of the baby and its blood type, and identify possible pathologies and hereditary diseases at an early stage.

Amniotic fluid index by week

To identify possible pathologies of amniotic fluid, an indicator such as the amniotic fluid index or AFI is used. It shows the volume of amniotic fluid. Depending on the value of this index, polyhydramnios or oligohydramnios is established.

Quantity amniotic fluid increases weekly by about 50 ml. The table reflecting the amount of amniotic fluid shows the average value of their volume, as well as the maximum permissible limits. Based on the volume of fluid in the cavity of the fetal bladder, one can identify problems such as earlier rupture of fetal fluid, weakness of the birth process, insufficient development of the baby due to poor oxygen supply, and predict bleeding that is possible after childbirth.

Causes of oligohydramnios

Many problems can lead to insufficient amniotic fluid:

• Problems of the genitourinary system.
• Genetic prerequisites for the development of a small amount of amniotic fluid.
• Problems with blood pressure, namely its high levels.
• The period of exacerbation of chronic diseases during pregnancy.
• Bacterial infection.
• Multiple pregnancy.
• The pregnancy is too advanced. Due to post-maturity, the placenta begins to deteriorate as its service life has expired. At the same time, the volume of fetal fluid decreases. In this case, labor is induced artificially.
• Different Rh factors in the blood of the fetus and mother.
• Diabetes mellitus.
• Various ailments of the placenta.
• Fetoplacental insufficiency.
• Poor development of the secretory layer or its pathology.

Oligohydramnios can have varying degrees. With moderate oligohydramnios, the decrease in the amount of fluid is moderate. It is not as dangerous as severe insufficiency of amniotic fluid, but it can still have an unpleasant effect on the child’s condition. Insufficiency of amniotic fluid can cause a child’s low weight, problems with the hip joints and various pathologies of the baby’s spine.

Causes of polyhydramnios

In other circumstances, the opposite condition occurs, when the amount of fetal fluid exceeds normal levels to one degree or another. The reasons that lead to this condition may be different. The exact cause may not always be identified, but there are several risk groups of women in whom polyhydramnios is more likely to develop:

• A pregnant woman suffers from diabetes.
• The expectant mother has various types of infections.
• Presence of kidney diseases.
• Pathologies of the heart and blood vessels.
• Different Rh factors in the blood of the fetus and mother.
• Pregnancy with two or more babies. In this case, there may be cases when one fetus has polyhydramnios, and the other has oligohydramnios.
• Fetal weight is too high.
• Weak excretory function of the fetus.
• The baby's swallowing function is impaired.
• The child has developmental defects.

Very often, a rapid increase in the amount of amniotic fluid has dangerous consequences. This condition is fraught with premature birth, chronic hypoxia of the fetus and its death, complex defects of the child’s internal organs develop, and the baby can become infected. With rapidly developing polyhydramnios, the likelihood of bleeding is high. During childbirth, the umbilical cord or part of the baby's body may fall out of the birth canal. In most cases, polyhydramnios causes a caesarean section.