Footnotes

• Collaborators NICU working group: Navapun Papana, Sariya Thongsawang, Chaweewan Prasertwitayakij and Nuananong Crutpant.

• Contributors VK: wrote the proposal, enrolled participants, provided physical examination, collected data, wrote the manuscript, and edited the final draft of manuscript. SK: edited the proposal and the manuscript, and read the final draft of the manuscript. WT: edited the proposal and the manuscript, supervised overall work, and read the final draft of manuscript. SC: edited the proposal and the manuscript, and read the final draft of the manuscript. KK: provided neurological assessment, edited the proposal and the manuscript, and read the final draft of the manuscript. OL: provided developmental assessment, edited the proposal and the manuscript, and read the final draft of the manuscript. NICU working group: NICU data collection.

• Funding This study was supported by the Faculty of Medicine, Chiang Mai University (grant number 046/2559).

• Competing interests None declared.

• Provenance and peer review Not commissioned; internally peer reviewed.