['To determine whether fetal breathing movements (FBM) in pregnancies with oligohydramnios change with restoration of amniotic fluid volume.', 'A prospective experimental study.', 'Fetal Medicine Unit, tertiary referral hospital.', '16 women with singleton pregnancies complicated by severe oligohydramnios.', 'Restoration of amniotic fluid volume by transabdominal amnioinfusion. Controls comprised pregnancies in which infused fluid leaked vaginally, so that oligohydramnios was not corrected.', 'Change in total breathing movements, change in FBM incidence derived from 40 min recordings immediately before and after amnioinfusion.', 'There was no significant difference in the change in total breathing movements or in the change in incidence of FBM between the 10 pregnancies in which amniotic fluid volume was restored, and the other six in which fluid leaked after infusion and volume was not restored. In both groups, there was no significant change with infusion in number of FBM (mean change -72, 95% CI -218 to +74 in the fluid-retained group and -64, 95% CI -273 to +145 in the fluid-leaked group) and incidence of FBM (median change -2.5%, range -27 to +10 in the fluid retained group and -4.5%, range -34 to +15 in the fluid-leaked group).'] Are fetal breathing movements in oligohydramnios increased by aminoinfusion?