Fetal breathing movements in oligohydramnios are not increased by amnioinfusion

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Abstract
Objective To determine whether fetal breathing movements (FBM) in pregnancies with oligohydramnios change with restoration of amniotic fluid volume. Design A prospective experimental study. Setting Fetal Medicine Unit, tertiary referral hospital. Subjects 16 women with singleton pregnancies complicated by severe oligohydramnios. Interventions: Restoration of amniotic fluid volume by transabdominal amnioinfusion. Controls comprised pregnancies in which infused fluid leaked vaginally, so that oligohydramnios was not corrected. Main outcome measures Change in total breathing movements, change in FBM incidence derived from 40 min recordings immediately before and after amnioinfusion. Results 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 −12, 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). Conclusions This study suggests that restitution of amniotic fluid volume in human pregnancies complicated by severe oligohydramnios does not acutely alter the incidence of FBM. These data support an increasing literature suggesting that impairment of fetal breathing is not the mechanism for oligohydramnios-related pulmonary hypoplasia.