Follow up at 1 and 2 years of corrected age for participants in the AZTEC study (Azithromycin Therapy for Chronic Lung Disease of Prematurity)

1. Respiratory outcomes measured using parent-reported wheezing at 1 year of corrected age
2. Survival (from birth) without combined moderate/severe neurodevelopmental disability measured using the Bayley Scales of Infant Development/PARCA-R questionnaire at 2 years of corrected age

1. Mortality measured using the total number of deaths occurring during the following periods:
1.1. From birth to one- and two-year corrected age
1.2. From birth to 36 weeks’ post-conceptual age (PCA)
1.3. 36 weeks to never discharged
1.4. After discharge.
2. Length of the initial neonatal stay in hospital measured using hospital records at 1 year corrected age
3. Number of children discharged home on domiciliary ambulatory oxygen measured using hospital records at 1 year corrected age
4. Length of oxygen supplementation (including at home) measured using hospital records at 1 year corrected age
5. Respiratory outcomes from discharge to two years of corrected age measured using parent-reported wheeze at 2 years of corrected age
6. Number of respiratory hospital admissions up to one year and two years of corrected age measured using hospital records at 1 and 2 years of corrected age
7. Number of prescribed respiratory drugs measured using hospital records at 1 and 2 years corrected age
8. Survival (from birth) without parent-reported wheeze measured from parent-report at 1 and 2 years of corrected age
9. Moderate/severe neurodevelopmental disability measured using PARCA-R or by using clinical data if PARCA-R scores are missing at 2 years of corrected age. Moderate/severe neurodevelopmental disability is defined, as any of the following:
9.1. Moderate or severe visual impairment (reduced vision uncorrected with aids, blindness in one eye with good vision in the contralateral eye, or blindness or light perception only)
9.2. Moderate or severe hearing impairment (hearing loss corrected with aids, some hearing loss uncorrected by aids, or deafness)
9.3. Moderate or severe gross motor impairment (inability to walk or sit independently)
9.4. Moderate or severe cognitive impairment will be defined using PARCA-R or by using clinical data if PARCA-R scores are missing. Total PARCA-R scores of less than 44 (range, 0 to 158, with lower scores indicating greater impairment) will be used to identify children with moderate or severe developmental impairment
10. Moderate or severe developmental impairment, defined as an Abilities–Revised (PARCA-R) questionnaire score of <44, measured using PARCA-R or by using clinical data if PARCA-R scores are missing at 2 years of corrected age
11. Overall motor skills as well as fine and gross motors scores measured using Bayley Scales of Infant Development/PARCA-R questionnaire at 2 years of corrected age
12. Overall language scores as well as expressive and receptive language scores measured using Bayley Scales of Infant Development/PARCA-R questionnaire at 2 years of corrected age
13. Overall cognition score measured using PARCA-R or by using clinical data if PARCA-R scores are missing at 2 years of corrected age
14. Growth measured using weight, height, and head circumference after adjusting for sex and gestation at 1 and 2 years of corrected age
15. Adverse Events measured using reports of the rates of reported pyloric stenosis in the active treatment and placebo groups at 1 year of corrected age
16. Cytokine, proteomic, and microbiome profiles of lung or stool samples as well as any modification that occurs in those colonised by Ureaplasma spp. measured using respiratory and stool samples collected during the AZTEC trial at baseline and at 5/7 and 14/21 days