What does the amount of amniotic fluid have to do with?

Amniotic fluid is a liquid that the fetus lives in the mother's body. It is an indispensable and important part for maintaining the life, health and development of the fetus. At different stages, the source of amniotic fluid will be different. Too much or too little amniotic fluid is not acceptable. For example, too much amniotic fluid may have adverse effects on the fetus and easily lead to deformities. Too little amniotic fluid may affect the fetus's breathing, etc. Let's take a look at this aspect.

What does the amount of amniotic fluid have to do with?

Amniotic fluid refers to the fluid in the amniotic cavity of the uterus during pregnancy. Throughout the pregnancy process, it is an important component that is indispensable for maintaining fetal life. The source of amniotic fluid varies at different stages of fetal development. During the first trimester of pregnancy, amniotic fluid mainly comes from the plasma components of the embryo; afterwards, as the embryo's organs begin to mature and develop, other sources of amniotic fluid, such as the fetal urine, respiratory system, gastrointestinal tract, umbilical cord, placental surface, etc., also become sources of amniotic fluid. Too little amniotic fluid or too much amniotic fluid may indicate fetal malformation, fetal size, or maternal complications, and further examination and repeat B-ultrasound should be performed.

Initially, some amniotic fluid may be secreted by cells of the mother's amnion; however, most of the fluid originates from maternal interstitial fluid that diffuses across the amnion; in addition, some fluid is secreted by the fetal respiratory tract, and fetal urine also contributes to the formation of amniotic fluid. So some people would say that amniotic fluid is equal to the fetus's urine. However, strictly speaking, the fetus's urine is only one of the main components of amniotic fluid.

Effects of too much or too little amniotic fluid on the fetus

1. Excessive amniotic fluid

If the AFI value is greater than 25 cm, it means "polyhydramnios". Common causes of polyhydramnios include multiple births, fetal malformations (such as hydrocephalus), gastrointestinal obstruction, gestational diabetes and unknown causes. If the amount of amniotic fluid exceeds a certain limit, it will cause the pregnant uterus to become larger, leading to uterine stretching and early uterine contractions, premature birth, and even rupture of the amniotic membrane and loss of amniotic fluid.

Amniotic fluid drainage

In order to avoid the problem of premature birth caused by excessive amniotic fluid, obstetricians will release the excess amniotic fluid, the so-called "amniotic fluid drainage", to reduce the burden on the mother's uterus, which will reduce the risk of premature birth.

2. Too little amniotic fluid

If the AFI value is less than 5 cm, it means "oligohydramnios". The most common cause of oligohydramnios is "water breaking", followed by fetal renal poor function or fetal arenal disease, placental insufficiency, etc. If the amount of amniotic fluid decreases, it will cause a smaller uterus, fetal malformation, early placental detachment, fetal limb deformities, and even affect the development of the fetus's lungs.