BACKGROUND Polyhydramnios may develop when the fetus cannot swallow amniotic fluid or the amount of fetal urine increases. Occasionally, unpredictable fetal abnormalities can be diagnosed postnatally. Bilateral vocal cord paralysis in the fetus may cause polyhydramnios, which could be related to impaired prenatal swallowing. METHODS A 36-year-old multipara underwent an emergent cesarean section because of polyhydramnios and active labor at 35 + 5 weeks of gestation and gave birth to a girl. METHODS The neonate cried feebly and exhibited cyanosis as well as very weak response to stimuli. Chest retraction and stridor were observed. Laryngoscopic examination revealed no movement in both the vocal cords, and bilateral vocal cord paralysis was diagnosed. METHODS When the baby was 40 days old, she underwent tracheostomy to alleviate the persistent stridor and oral feeding difficulties. RESULTS She was discharged at the age of 60 days while in the tracheostomy state. CONCLUSIONS Securing the airway of neonates with bilateral vocal cord paralysis, tracheoesophageal fistula, or muscular dystrophy, which can be detected after delivery in pregnant women with idiopathic polyhydramnios, is important. Therefore, pregnant women with idiopathic polyhydramnios must be attended to by experts, such as neonatologists, anesthesiologists, or otolaryngologists, who can secure the airway.