Table 1

Characteristics of the included studies

StudyPublication yearCountryStudy designGestational age/BWSample sizeBPD definitionPrimary outcomeAdjusted confounder variablesNOS score
Gagliardi et al 26 2009ItalyCohort study<32 weeks and BW <1500 g1209BPD (at 36 weeks’ PMA)ORs=2.16 (CI 1.1 to 3.9)GA, propensity score for prolonged ventilation, centre6
Kim et al 15 1999KoreaCase–control<37 weeks184BPD (oxygen dependence at 28 days)ORs=1.12 (CI 0.85 to 1.5)Apgar score at 5 min, IVH, PDA, sepsis, duration of mechanical ventilation7
Lodha et al 27 2011CanadaCohort study<28 weeks918NAORs=2 (CI 1.2 to 3.2)NA6
Natarajan et al 25 2012NACohort study<27 weeks BW <1000 g1189BPD (at 36 weeks’ PMA)ORs=2.41 (CI 1.4 to 4.13)GA, male gender, SGA, maternal education, surgical NEC, IVH or PVL7
Palta et al 29 2000USACohort studyBW <1500 g1024Severe BPDORs=2.3 (CI 1.2 to 4.6)NA6
Schlapbach et al 18 2010SwitzerlandCase–control study<32 weeks99BPD (at 36 weeks’ PMA)ORs=3.75 (CI 1.08 to 11.14)Gestational age, birth weight, postnatal growth, mechanical ventilation7
Synnes et al 24 2017CanadaCohort study<29 weeks3700BPD (at 36 weeks’ PMA)ORs=1.42 (CI 1.17 to 1.73)NA8
Tran17 2005AustraliaCase–control<27 weeks150NA home oxygenORs=3.4 (CI 1.2 to 9.4)NA6
Van Marter et al 14 2011USACohort study<28 weeks1047BPD (at 36 weeks’ PMA)
BPD (mechanical ventilation at 36 weeks)
ORs=1.77 (CI 1.02 to 3.77)
ORs=5.16 (CI 2.62 to 10.16)
Wang et al 28 2014ChinaCohort studyGA <30 weeks and BW <1500 g5807Not mentionedORs=3.14 (CI 2.61 to 3.85)GA, BW, sex, ROP grade ≥III, grade III/IV IVH and PVL8
Bashir et al 16 2016CanadaRetrospective observational studyBW <1250 g1563BPD (at 36 weeks’ PMA)ORs=1.3 (CI 0.87 to 1.96)GA, male gender, ANCS use, Apgar score <7 at 5 min, SGA, postnatal steroids, blood transfusion, PDA, IVH grade ≥III and/or PVL, ROP grade ≥III and/or required laser treatment and postnatal sepsis8
  • ANCS, antenatal corticosteroids; BPD, bronchopulmonary dysplasia; BW, birth weight; GA, gestational age; IVH, Intraventricular hemorrhage; NA, not available; NEC, neonatal necrotising enterocolitis; NOS, Newcastle-Ottawa Scale; PDA, patent ductus arteriosus; PMA, postmenstrual age; PVL, Periventricular Leukomalacia; ROP, retinopathy; SGA, small for gestational age.