What characterizes oligohydramnios?

Oligohydramnios is characterized by a deficiency of amniotic fluid surrounding the developing fetus. Specifically, this condition is typically defined as having less than 300 mL of amniotic fluid. Amniotic fluid is crucial for fetal development as it provides cushioning, enables fetal movement, and facilitates lung development. When the volume of this fluid is insufficient, it can lead to a range of complications for both the fetus and the mother.

In the context of the other options, excessive amniotic fluid is known as polyhydramnios, which is the opposite of oligohydramnios and is not relevant here. The presence of meconium, which is the first stool of the fetus, does not directly define oligohydramnios; it can occur in various conditions and has different implications. Finally, normal levels of amniotic fluid would not be classified as oligohydramnios, as that implies a sufficient volume of fluid, contrasting with the low volume characteristic of the condition.