Amniotic sac: important habitat
The unborn child finds all the conditions for healthy development in its habitat, the amniotic sac. This includes, above all, the amniotic fluid, from which it can obtain important substances for its development. In addition, the amniotic fluid enables the child to move freely. This allows it to build up its muscles and grow evenly.
In the course of pregnancy, both the mother and the child produce amniotic fluid and absorb used amniotic fluid. These exchanges are regulated by a variety of mechanisms. For example, the maternal placenta as well as the fetal kidneys, lungs, mouth or nose are involved. Minor disturbances therefore quickly cause an imbalance, which manifests itself as too much amniotic fluid (polyhydramnios) or too little amniotic fluid (oligohydramnios).
Triggers for too little amniotic fluid
If a pregnant woman’s amniotic sac contains too little amniotic fluid, the following causes are possible:
- functional weakness of the placenta (placental insufficiency)
- Diseases of the fetal renal system
- high blood pressure in the mother or child
- premature rupture of the membranes
- insufficient growth of the child
- congenital genetic defects
- Transfusion syndrome in twin pregnancies, when the children share the same placenta but each has its own amniotic sac: Uneven blood exchange between the children can result in one twin being undersupplied and “swimming” in too little amniotic fluid.
How does the doctor detect too little amniotic fluid?
The doctor can determine if there is too little amniotic fluid during routine ultrasound exams. Usually, his trained eye is enough for this. His suspicion can be underlined by the following values from various measurements:
- Amniotic fluid index (values below five centimeters)
- Two-diameter fruiting water depot (values less than 15 square centimeters).
Too little amniotic fluid: Dangers
If the amniotic sac contains too little amniotic fluid, this can endanger the unborn child. This is because a reduced amount of amniotic fluid can cause the baby to be unusually small at birth. If placental dysfunction is responsible for the reduced amount of amniotic fluid, the worst-case scenario may be infant death around the time of birth.
Furthermore, too little amniotic fluid increases the likelihood that the umbilical cord will become entrapped. Then the baby will be supplied with too little oxygen and other vital substances. Squeezing the umbilical cord before or during birth therefore carries great risks. It is more common for the unborn child to excrete and inhale stool (= meconium) while still in the womb or during birth (= meconium aspiration). This impairs its breathing and can have further serious consequences.
No reason to panic
Despite the possible dangers described, there is usually no reason for pregnant women with too little amniotic fluid to worry. An infusion of a solution similar to amniotic fluid into the amniotic sac is often sufficient. If the pregnancy is already advanced or the due date has passed, medically controlled induction of labor – by cesarean section if necessary – can be considered.
So the bottom line is: too little amniotic fluid poses certain dangers, but modern medicine can now do a lot to prevent harm to mother and child.
