Causes of oligohydramnios include the following: Uteroplacental insufficiency (eg, due to preeclampsia, chronic hypertension, placental abruption, a thrombotic disorder, or another maternal disorder) Rupture of membranes (premature or at term) Postterm pregnancy Some medications (eg, angiotensin-converting enzyme [ACE] inhibitors, nonsteroidal anti-inflammatory drugs [NSAIDs]) Fetal chromosomal abnormalities (eg, aneuploidy) Fetal malformations, particularly those that decrease urine production Intrauterine growth restriction Fetal death Idiopathic Complications Complications of oligohydramnios include the following: Fetal death Intrauterine growth restriction Limb contractures (if oligohydramnios begins early in the pregnancy) Delayed or incomplete lung maturation (if oligohydramnios begins early in the pregnancy) Inability of the fetus to tolerate labor, leading to the need for cesarean delivery Risk of complications depends on how much amniotic fluid is present and what the cause is.