Commonly used for treatment of acute and chronic pain in different medical conditions, Diclofenac has been described as tocolitic therapy in animal but has not been approved with this proposes in human beings cause crosses the human placenta and it has been isolated in fetal tissue samples as in amniotic fluid. Data do not support association with mayor anomalies during first trimester of pregnancy but haemodynamic changes when used at third trimester. We describe three cases with hydramnios, fetal haemodynamic changes and well-being compromise in association with previous use of Diclofenac as a pain killer. First case was a 33wo pregnancy patient who received Diclofenac 75 mg twice a day as management for lumbar pain secondary to muscle disbalance. Ultrasound showed oligohydramnios, cardiomegaly with predominant right ventricle and Doppler evaluation showed high resistance of the umbilical artery (UA) and high impedance of ductus venosus (DV). Patient underwent emergency C-section because of well-being alterations. A female infant was delivered and went to neonatal ICU and postnatal echocardiography showed cardiomegaly, incipient right heart failure and complete ductus arteriosus closure. Second case was a 34wo pregnancy woman with acute abdominal pain secondary to pielonephritis, a 75 mg dose of Diclofenac was administered. Sonogram showed oligohydramnios, cardiomegaly and high resistance of DV. Postnatal echocardiography confirmed data. Third case was a 39yo woman with previous diagnosis of arthritis with a 35wo pregnancy and acute pain. Single 75 mg dose of Diclofenac was injected. Ultrasound revealed oligohydramnios and constriction of DV. Acute well-being alteration was documented and patient underwent to C-section. Complete neonatal correlation of findings were reported. In spite of Diclofenac is a useful medication in pain treatment, its uses during pregnancy should be closely monitorized due to acute adverse effects as a perinatal life threatening situation.