Risk factors for very preterm delivery out of a level III maternity unit: The EPIPAGE-2 cohort study

BACKGROUND Regionalisation programmes aim to ensure that very preterm infants are born in level III units (inborn) through antenatal referral or transfer. Despite widespread knowledge about better survival without disability for inborn babies, 10%-30% of women deliver outside these units (outborn). OBJECTIVE To investigate risk factors associated with outborn deliveries and to estimate the proportion that were probably or possibly avoidable. METHODS We used a national French population-based cohort including 2205 women who delivered between 24 and 30+6 weeks in 2011. We examined risk factors for outborn delivery related to medical complications, antenatal care, sociodemographic characteristics and living far from a level III unit using multivariable binomial regression. Avoidable outborn deliveries were defined by pregnancy risk (obstetric history, antenatal hospitalisation) and time available for transfer. RESULTS 25.0% of women were initially booked in level III, 9.1% were referred, 49.8% were transferred, and 16.1% had outborn delivery. Risk factors for outborn delivery were gestational age