Study population
The study population consisted of 136 children from three prospective
cohorts(9, 15, 16) of very preterm infants
(gestational age <32 weeks), one also including 56 term born
controls (see Table 1 and online supplement for details). Antenatal and
neonatal data were collected prospectively from the patient records.
There were 85 children with and 51 without a previous diagnosis of
bronchopulmonary dysplasia (BPD), defined as being born at <
32 weeks gestation and still being treated with extra oxygen at 36 weeks
postmenstrual age. A history of respiratory symptoms, medication and
allergy was obtained from a questionnaire completed by the accompanying
parent/caregiver at the 12-year visit.