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What is Oligohydramnios is associated with and explain in detail?
Etiology of oligohydramnios: 

Intrauterine growth restriction
Post-term pregnancy 
Premature rupture of membrane 
Drugs like ACE inhibitors and prostaglandin inhibitors 
Renal anomalies 
Renal Agenesis 
Infantile polycystic disease 
Upper urinary tract obstructions 
Lower urinary tract obstructions