This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amniotic Fluid Dynamics, Subject name: Gynaecology & Obstetrics
A 20 year old primi at 30 weeks of gestation has polyhydraminos. She should be advised:- 
Select and explain. 
A. Bed Rest, B. Aificial rupture of membranes, C. Oral indomethacin, D. Restriction of oral fluid
C: Oral indomethacin
Answer: C: Oral indomethacin 
Explanation: Indomethacin acts by decreasing fetal urine production and thereby reduces amnionic fluid volume. This is presumed due to an increase in vasopressin levels and vasopressin responsiveness However, it may cause constriction of fetal ductus aeriosus, resulting in pulmonary hypeension. Hence, should not be used beyond 32 weeks