PTGS2 and oligohydramnios: It has been reported that renal development is impaired in COX-2-deficient mice.43,44 After mother’s use of nimesulide (selective COX-2 inhibitor NSAID) as tocolytic, the lack of effect of nimesulide on fetal renal and ductal function indicates that fetal prostaglandin synthesis is mainly mediated by the COX-1 isoform.45 However, some studies reported neonatal irreversible end-stage renal failure or severe oligohydramnios after use of nimesulide as a tocolytic.46,47