[Is it possible to prevent preterm births outside of level-3 maternity wards? Experience of Greater Lyon perinatal network]

Objective: The main objective of this study was to calculate the percentage of preterm births before 28 weeks gestational age (weeks GA) outside level-3 maternity wards and determine how many could have been prevented.

Methods: This was an observational, multicenter, retrospective cohort study, which included all the deliveries that occurred between 24 and 27 weeks GA + 6 days in the Greater Lyon perinatal network (France) occurring between first of March 2008 and first of March 2009. In utero transfers (IUTs) and newborn transfers (NBTs) which were carried out outside the network, medical abortions, and foetal deaths in utero were excluded. The duration between patient's arrival in the level 1 and 2 maternity and birth was compared at the 97(th) percentile of the mother's transfer time in level-3 maternity. Births that occurred outside of level-3 maternity wards were considered avoidable each time the first duration was more than the second.

Results: During the study period, 113 infants were born alive between 24 and 27 weeks GA+6 days in the network. They were all included in the study. Ninety were born in a level-3 maternity ward and 23 were born in level-1 and 2 maternity wards (20%). There were 35 requests for IUT and 28 were carried out (80%). In 65% of non-level 3 births, no IUT was requested. In 17% of cases, an IUT request could have prevented births in level 1/2 maternity wards. If twin pregnancies had been transferred to a level-3 maternity ward, 26% of non-level 3 births would have been avoided. If all high-risk pregnancies had been transferred to a level-3 maternity ward, 40% of non-level 3 births would have been avoided.

Discussion and conclusion: Any time a pregnant woman is hospitalized in a type 1/2 maternity ward before 28 weeks GA, doctors should consider an in utero transfer to a level-3 maternity ward. It may be possible to lower the birth-rate of non-level 3 births by a targeted increase in in utero transfers and by transferring high-risk pregnancies to a level-3 maternity ward.