Patterns of Delivery Following in Utero Transfer for Extremely Preterm Birth: A Retrospective Cohort Study From a London Tertiary Centre

ABSTRACT Aim To evaluate delivery patterns following in utero transfer (IUT) to a London tertiary neonatal intensive care unit, examining gestational age, referral indication, transfer‐to‐delivery interval, and maternal length of stay. Methods Retrospective cohort study of women accepted for IUT at St George's Hospital, London (2021–2025), between 22 + 0–27 + 6 weeks' gestation (or 28–29 weeks with multiples/expected birth weight < 800 g) for threatened extremely preterm birth. Data were extracted from BadgerNet, maternity records, and delivery suite databases; Fisher's exact test was used for categorical comparisons. Results Of 126 IUT episodes, 53 (42%) delivered at the tertiary centre; median transfer‐to‐delivery interval was 1 day (mean 2.02). Delivery rates averaged ~10%/day over the first 5 days. Transfers from outside the local network delivered within 24 h more often (18%). Among 73 (58%) who did not deliver, median length of stay was 4 days. Delivery was less likely at 22–24 weeks (32% vs. 50% at ≥ 25 weeks) and significantly associated with sepsis ( p = 0.01), chorioamnionitis ( p < 0.001), pathological CTG ( p = 0.006), and Doppler abnormalities ( p = 0.02). Conclusion Over half of women undergoing IUT did not deliver during admission. Infection and fetal compromise indications were most strongly associated with delivery, supporting liberalised IUT acceptance and capacity planning.