UNLABELLED: It is known that in most cases of congenital central hypoventilation syndrome (CCHS), apnoeas and hypoventilation occur at birth. Nevertheless, a detailed description of initial symptoms, including pregnancy events and diagnostic tests performed, is warranted in infants with neonatal onset of CCHS, that is, in the first month of life. The European Central Hypoventilation Syndrome Consortium created an online patient registry from which 97 infants (44 females) with CCHS of neonatal onset and PHOX2B mutation from 10 countries were selected. The typical pregnancy is characterized by polyhydramnios (44%), fetal heart rate abnormalities on cardiotocography (36%), emergency cesarean sections. (30%) and a normal gestational age (14% preterm birth). The typical findings within the first days are the presence of respiratory distress (96%), often necessitating rapid intubation (44%) and, less frequently, cardiopulmonary resuscitation at birth (14%). These symptoms lead to a suspicion of CCHS after (median [interquartile]) 7 days [4
12] since birth that is confirmed by genotype testing at 32 days [22
61]. Daytime evaluation of blood gas is a frequent assessment leading to CCHS suspicion (n = 61/97, 63%
95% confidence interval: 52-72) while a polysomnography is obtained in 45/97 infants (46%, 95% confidence interval: 36-57), demonstrating NREM hypoventilation in 44/45 infants (98%). CONCLUSION: Our multicentre descriptive study shows that polyhydramnios is overrepresented during pregnancy, rapid respiratory failure is the main symptom leading to intubation in approximately half of infants and daytime alveolar hypoventilation is the main indicator prompting genetic testing. WHAT IS KNOWN: • The initial symptoms and exams leading to congenital central hypoventilation syndrome diagnosis have mainly been described in single centre studies. WHAT IS NEW: • Our multicentre European study confirms that polyhydramnios is overrepresented during pregnancy and that polysomnography is obtained in half of the infants only.