AbstractAimChronic abruption‐oligohydramnios sequence (CAOS), which is characterized by vaginal bleeding and oligohydramnios, adversely affects the lungs of fetuses due to bloody amniotic fluid and oligohydramnios. The criteria for termination of pregnancy remain controversial. This study aimed to examine respiratory function in infants within 3 years after birth and risk factors for respiratory prognosis, and to clarify the management of CAOS.MethodsThis study is a case series of patients with CAOS managed at our institution between 2010 and 2020. The clinical data of the patients and their infants within 3 years after birth were reviewed. The amniotic fluid volume was measured using the maximum vertical pocket (MVP).ResultsSix of 17 neonates (35.3%) used inhaled nitric oxide (iNO) to improve oxygenation. Women with longer periods of MVP <1 cm delivered more neonates using iNO; however, periods of MVP <2 cm were not associated with iNO use. Almost half of the infants required home oxygen therapy when discharged, regardless of amniotic fluid volume. At 18 months corrected age, only one child needed respiratory support, and the others discontinued. Two neonates, both born at 23 weeks of gestational age, died within 1 month after birth because of extremely preterm birth.ConclusionsThe amniotic fluid volume could predict the use of iNO in neonates, but it did not affect the child's respiratory function after the newborn period. Almost all children born to women with CAOS can improve their respiratory function as they grow up.