A 20 year old primi at 30 weeks of gestation has polyhydraminos. She should be advised:-

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