Oligohydramnios is caused by which of the following?

• A. Increased amniotic fluid production
• B. Low amniotic fluid volume due to fetal kidney anomalies or leakage of fluid
• C. Elevated maternal blood pressure
• D. Fetal overgrowth

Answer: (B)

Oligohydramnios means there isn’t enough amniotic fluid. In the later stages of pregnancy, the fetus provides most of this fluid through urine, so when fetal kidneys aren’t functioning properly (kidney anomalies) or when fluid leaks from the membranes (premature rupture), the amniotic fluid volume drops. That’s exactly what the option describes: a low amniotic fluid volume due to fetal kidney issues or leakage.

Increasing fluid production would lead to polyhydramnios, not oligohydramnios. Elevated maternal blood pressure can contribute to reduced placental perfusion and may indirectly lower fluid, but the direct mechanism in this scenario is decreased production or loss of fluid. Fetal overgrowth isn’t a typical cause of reduced amniotic fluid.