Immature lungs
Very preterm birth interrupts normal lung development during a period of rapid structural and vascular growth.
UK multicentre neonatal trial
AZTECAzithromycin Therapy for Chronic Lung Disease of Prematurity
A UK-wide clinical trial investigating whether azithromycin given soon after birth could improve outcomes for babies born very preterm.
799 babies
28 neonatal intensive care units
Recruitment complete
Results published
AZTEC in animation
Watch the AZTEC results animation
This AZTEC-owned animation explains why the study was undertaken, what treatment was tested and what the trial found.
It does not autoplay, and the privacy-enhanced YouTube player is used.
About AZTEC
Why was the AZTEC Trial needed?
Babies born very preterm are at increased risk of chronic lung disease because their lungs are still developing and are exposed to inflammation, respiratory support and infection during a critical period of lung growth.
AZTEC tested whether the antibiotic azithromycin, which has both antimicrobial and anti-inflammatory properties, could improve outcomes when given early after very preterm birth.
AZTEC at a glance
A UK-wide neonatal randomised controlled trial
799 babies born before 30 weeks’ gestation were recruited across neonatal intensive care units throughout the UK.
The clinical problem
Chronic lung disease after very preterm birth
Chronic lung disease of prematurity—often referred to as bronchopulmonary dysplasia or BPD—remains one of the commonest important complications of very preterm birth.
Inflammation and infection
Inflammatory injury and microorganisms including Ureaplasma have been implicated in the development of chronic lung disease.
The research question
What did AZTEC test?
The trial compared a 10-day course of intravenous azithromycin with placebo in infants born before 30 weeks’ gestation who required respiratory support soon after birth.
Population<30 weeksVery preterm infants requiring respiratory support.
RandomisationAzithromycinEarly intravenous treatment for 10 days.
ComparatorPlaceboMatched placebo in a double-blind design.
OutcomeSurvival without CLDPhysiologically defined moderate/severe chronic lung disease.
The AZTEC story
A national collaboration
2019Trial beginsAZTEC opens recruitment across UK neonatal units.
2020–21COVID disruptionRecruitment continues despite national pauses and service pressures.
2022799 babiesRecruitment completes above the original target of 796.
2024Primary resultsThe main RCT is published in The Lancet Respiratory Medicine.
2025–26Research continuesFollow-up, laboratory and antimicrobial-resistance work continue.
Who made AZTEC possible?
Families, neonatal teams and collaborators across the UK
The trial involved 28 neonatal intensive care units and more than 50 continuing-care or step-down units. The contribution of participating babies, families, nurses, doctors, research teams and pharmacists was fundamental to the study.
Leadership & collaboration
The AZTEC team
AZTEC was led from the Department of Child Health at Cardiff University and coordinated by the Centre for Trials Research.
Chief Investigator
Professor Sailesh Kotecha
Department of Child Health, Cardiff University
Trial coordination
Centre for Trials Research
Cardiff University
UK collaboration
Co-applicants and collaborators from Newcastle, Leicester, Liverpool, UCL, Imperial College London and participating neonatal units across the UK.
Funding & governance
How was AZTEC supported?
AZTEC was funded by the NIHR Health Technology Assessment Programme (HTA Project 16/111/106) and registered as ISRCTN11650227.
The study received the relevant UK research ethics, Health Research Authority and medicines-regulatory approvals required for the trial.
AZTEC results
What did the AZTEC Trial find?
AZTEC asked whether giving azithromycin soon after birth could improve survival without chronic lung disease in babies born before 30 weeks’ gestation.
The answer: routine early prophylactic azithromycin did not improve survival without physiologically defined moderate or severe chronic lung disease.
799 randomised796 analysed28 UK NICUsPublished 2024
Primary outcome
42.1%166/394
Azithromycin
Azithromycin
vs
44.5%179/402
Placebo
Placebo
Adjusted OR 0.84
95% CI 0.55–1.29 · P=0.43
AZTEC in animation
Watch the AZTEC results animation
This AZTEC-owned animation explains why the study was undertaken, what treatment was tested and what the trial found.
It does not autoplay, and the privacy-enhanced YouTube player is used.
AZTEC follow-up
Following AZTEC children as they grow
The neonatal trial answered whether early azithromycin improved survival without chronic lung disease. Follow-up asks a different question: what happens to respiratory health, development and growth after children leave neonatal care?
Birth → 2 years
AZTEC-FU follows outcomes beyond the neonatal admission.
AZTEC in animation
Watch the AZTEC results animation
This AZTEC-owned animation explains why the study was undertaken, what treatment was tested and what the trial found.
It does not autoplay, and the privacy-enhanced YouTube player is used.
For AZTEC families
Thank you for being part of AZTEC
799 babies and their families took part in AZTEC. Your contribution helped answer an important question about how best to care for babies born very preterm.
AZTEC in animation
Watch the AZTEC results animation
This AZTEC-owned animation explains why the study was undertaken, what treatment was tested and what the trial found.
It does not autoplay, and the privacy-enhanced YouTube player is used.
For researchers & clinicians
AZTEC scientific resources
Trial design, statistical methods, follow-up methodology, peer-reviewed publications and archived study documentation from the AZTEC research programme.
Trial design
Multicentre, double-blind, randomised, placebo-controlled
799 infants born before 30 weeks’ gestation were randomised; 796 remained in the final analysis after three complete withdrawals.
AZTEC publications
Scientific outputs from AZTEC
Peer-reviewed publications covering the trial protocol, statistical methods, primary clinical results, follow-up design, antimicrobial resistance and the full NIHR programme report.
Featured publication
The primary AZTEC randomised controlled trial
The Lancet Respiratory Medicine, 2024
AZTEC news
Research, follow-up and the AZTEC story
The new News section prioritises scientific results and follow-up while retaining recruitment milestones as part of the historical record.
Featured updates
Latest from AZTEC
February 2026
Results
AZTEC results animation available
The AZTEC animation provides a clear visual explanation of the clinical question and principal trial result.
View results →June 2025
Research meeting
AZTEC Investigators’ Study Day
Investigators and invited experts discussed findings from the primary AZTEC trial together with emerging laboratory and follow-up analyses.
Research outputs →August 2024
Primary RCT
Main AZTEC results published
The primary randomised controlled trial was published in The Lancet Respiratory Medicine, showing no improvement in survival without moderate or severe chronic lung disease with routine prophylactic azithromycin.
Explore the results →July 2023
Follow-up
First-year follow-up questionnaires completed
The final one-year questionnaire was mailed in July 2023; more than 500 completed first-year questionnaires had already been returned by families at that point.
Follow-up programme →March 2022
Trial history
AZTEC completes recruitment at 799 babies
Recruitment finished above the original target of 796 participants following an extraordinary UK-wide neonatal collaboration.
Read the AZTEC story →Archive
Recruitment milestones
Older posts documenting 150, 200, 250, 500, 600 and 700 recruits remain part of the trial’s history, but they no longer need to dominate the modern website.
Recommended approach: retain the original WordPress posts in an “AZTEC history” archive, preserving dates and institutional memory while keeping the main News page focused on scientific outputs and follow-up.
Contact AZTEC
How can we help?
Choose the most appropriate route for family follow-up, research enquiries or archived trial documentation.
Main AZTEC contact
AZTEC Team
Department of Child Health
Cardiff University
Cardiff, UK
aztecat1@cardiff.ac.uk
For families
Follow-up or contact-detail changes
If your family took part in AZTEC and you need to update your address, telephone number or other contact details, please contact the AZTEC team.
aztecat1@cardiff.ac.uk
For researchers
Scientific and collaboration enquiries
For questions about AZTEC methods, publications, follow-up or potential scientific collaboration, use the AZTEC team contact in the first instance.
Trial archive
Historical study documentation
Operational trial documents, forms, guidance and archived site resources are retained within the researcher archive.
Privacy & data protection
Questions about your information
AZTEC research information is managed under Cardiff University research-governance and data-protection arrangements.
For questions about AZTEC participant information or to exercise data-protection rights in relation to the study, families can contact the AZTEC team at aztecat1@cardiff.ac.uk.
Useful routes
Looking for something specific?
Privacy
AZTEC Study Privacy Notice
This notice explains how personal information relating to children who took part in AZTEC is collected, used, stored and protected.
Study contact
AZTEC Team, Department of Child Health, Cardiff University, Cardiff
Email: aztecat1@cardiff.ac.uk
AZTEC Team, Department of Child Health, Cardiff University, Cardiff
Email: aztecat1@cardiff.ac.uk
What personal information we collect
For children recruited to AZTEC, the study may hold personal identifiers and contact details, including name, date of birth, NHS number and family contact details, together with health information where the appropriate consent and approvals apply.
Where the information comes from
Information was collected when children joined AZTEC and through subsequent follow-up. Contact details may be updated through healthcare records where permitted. Health information may also come from parents, general practitioners, hospitals, NHS datasets and neonatal research databases where approved.
Why we use the information
AZTEC uses these data to understand respiratory health, development and growth after very preterm birth and to evaluate the longer-term effects of the treatment assigned during the neonatal trial.
Our legal basis
Cardiff University processes personal data for this research under the UK GDPR legal basis of public task, for scientific research in the public interest and subject to appropriate safeguards. This legal basis is separate from research consent and duties of confidentiality.
Sharing information
Where necessary and appropriately approved, information may be shared with organisations that provide additional health information for the research. Identifiable information is shared only when needed for an approved purpose and under appropriate safeguards.
How long information is kept
The current AZTEC privacy notice states that study information is retained securely for 25 years in accordance with University policy, after which records are securely destroyed or deleted as required.
Your data-protection rights
Depending on the circumstances, data-protection rights may include access, rectification, erasure, restriction, objection and data portability. Research exemptions can affect how some rights apply. To make a request, contact the AZTEC team at aztecat1@cardiff.ac.uk.
How to raise a concern
Concerns about use of participant information can be raised with the AZTEC team. The Cardiff University Data Protection Officer can also be contacted independently at inforequest@cardiff.ac.uk.
You also have the right to complain to the Information Commissioner's Office if you are unhappy with how personal information has been used.
Before launch: this rewritten notice should be checked against the current Cardiff University research privacy wording and the approved AZTEC/AZTEC-FU documentation. It preserves the substance of the existing AZTEC privacy notice but presents it in a clearer structure.
Accessibility
Accessibility statement for the AZTEC Trial website
Cardiff University is committed to making the AZTEC Trial website accessible to as many people as possible.
Using this website
The redesigned site is intended to allow users to:
- zoom text without loss of content or functionality;
- navigate using a keyboard;
- use clear headings and meaningful link text;
- access text alternatives for informative images;
- use the site on mobile, tablet and desktop layouts;
- view the AZTEC animation without autoplay.
Compliance status
Staging status — formal assessment required before publication.
The redesign has been built toward the Web Content Accessibility Guidelines (WCAG) version 2.2 AA standard. A final compliance statement should only be selected after the staging site has been tested against WCAG 2.2 AA.
Accessibility features built into the redesign
Keyboard accessVisible focus indicators and a skip link are included.
Responsive layoutContent reflows for smaller screens without separate mobile-only content.
Reduced motionThe design respects the user's reduced-motion preference.
ImagesInformative images have descriptive alternative text; decorative elements should use empty alt text.
VideoThe results animation does not autoplay and is given a descriptive title.
StructureSemantic headings, sections and navigation landmarks are used throughout.
Known items to verify on the staging site
- keyboard operation of the final WordPress mobile menu;
- colour contrast after the official AZTEC logo and final brand colours are applied;
- captions and/or transcript availability for the AZTEC animation;
- accessibility of archived PDF and Word trial documents;
- form labels and validation if a contact form is added;
- focus order and skip-link behaviour in the final WordPress theme.
Feedback and contact information
If you need information from this website in another format, or experience an accessibility problem, contact the AZTEC team at aztecat1@cardiff.ac.uk.
Preparation of this statement
This draft statement was prepared for the 2026 AZTEC website redesign. The final public version should record the date of the WCAG 2.2 AA assessment, who performed it, the confirmed compliance status, and any outstanding non-compliances or exemptions.