Persistent pulmonary hypertension and abnormal prostaglandin E levels in preterm infants after maternal treatment with naproxen.

Twins and a singleton were born at 30 weeks' gestation although naproxen (d-2 (6'methoxy-2-naphthyl) propionic acid) had been given to the mothers in an attempt to delay parturition. Inhibition of prostaglandin synthesis was shown by very low plasma concentrations of prostaglandin E and the ductus arteriosus remained closed despite signs of pulmonary hypertension with severe hypoxaemia. Abnormalities in blood clotting, renal function, and bilirubin metabolism were also found and one infant died. Further studies of the benefits and risks of the inhibition of prostaglandin synthesis are required before this treatment of preterm labour is accepted.