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

Thomas Desplanches (1, 2) , Andrei Morgan (2, 3, 4) , Peter Jones (5, 6) , Caroline Diguisto (7, 2) , Jennifer Zeitlin (2) , Laetitia Martin‐marchand (2) , Valérie Benhammou (2) , Bénédicte Lecomte (8, 9) , Jean‐christophe Rozé (10) , Patrick Truffert (11, 12) , Pierre‐yves Ancel (2, 13) , Paul Sagot (14) , Adrien Roussot (15, 16) , Jeanne Fresson (2, 17) , Béatrice Blondel (2)

1 Service de Gynécologie Obstétrique, Médecine Foetale et Stérilité Conjugale - Chirurgie Gynécologie et Oncologique [CHU de Dijon]
2 EPOPé [CRESS - U1153 / UMR_A 1125] - Obstetrical, Perinatal and Pediatric Epidemiology | Épidémiologie Obstétricale, Périnatale et Pédiatrique
3 UCL - University College of London [London]
4 Sheffield Children's NHS Foundation Trust
5 Hôpital Necker - Enfants Malades [AP-HP]
6 AP-HP Hôpital universitaire Robert-Debré [Paris]
7 Service de Gynécologie-Obstétrique [CHRU Tours]
8 CHU Estaing [Clermont-Ferrand]
9 IP - Institut Pascal
10 CHU Nantes - Centre Hospitalier Universitaire de Nantes = Nantes University Hospital
11 CHRU Lille - Centre Hospitalier Régional Universitaire [CHU Lille]
12 Hôpital Jeanne de Flandre [Lille]
13 AP-HP - Hôpital Cochin Broca Hôtel Dieu [Paris]
14 CHU Dijon
15 DIM - Service Biostatistiques et Informatique Médicale (CHU de Dijon)
16 UB - Université de Bourgogne
17 Service d'Evaluation et Information Médicales [CHRU Nancy]

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 <26 weeks (adjusted relative risk (aRR) 1.37, 95% confidence interval (CI) 1.13, 1.66), inadequate antenatal care (aRR 1.39, 95% CI 1.10, 1.81), placental abruption (aRR 1.66, 95% CI 1.27, 2.17), and increased distance to the closest level III unit ((aRR 2.79, 95% CI 2.00, 3.92) in the 4th versus 1st distance quartile). Among outborn deliveries, 16.7% were probably avoidable, and 25.6% possibly avoidable, which could increase the proportion of inborn deliveries between 85.9% and 92.9%. Avoidable outborn deliveries were mainly associated with gestational age, intrauterine growth restriction, preterm premature rupture of membranes, and haemorrhage, but not distance. Conclusions: Our study identified some modifiable risk factors for outborn delivery; however, when regionalised care relies heavily on antenatal transfer, as it does in France, only some outborn deliveries may be prevented. Earlier referral of high-risk women will be needed to achieve full access to tertiary care.

Keywords: antenatal transfer; geographical access; obstetric care; perinatal epidemiology; place of delivery; very preterm birth

Domains: Santé publique et épidémiologie

Thomas Desplanches, Andrei Morgan, Peter Jones, Caroline Diguisto, Jennifer Zeitlin, et al.. Risk factors for very preterm delivery out of a level III maternity unit: The EPIPAGE‐2 cohort study. Paediatric and Perinatal Epidemiology, 2021, 35 (6), pp.694-705. ⟨10.1111/ppe.12770⟩. ⟨hal-03472188⟩