DNA Methylation of SLC6A4 and NR3C1 in Term and Preterm Infants: A Pilot Study of NICU-Associated Stress.

This was a pilot with 10 term infants and 23 preterm infants, and only 11 preterm infants completed the 3-month follow-up, so the results are preliminary. Term infants were measured only once and had no NICU stress score, so follow-up changes and stress comparisons were possible only in preterm infants. Preterm infants reached the 3-month visit at different corrected gestational ages because discharge timing varied, so some differences may reflect maturity rather than NICU stress. The NICU stress score depends on charted clinical events and complete bedside nursing documentation, and it has poor concurrent validity with other stress measures. The study measured DNA methylation, not health or developmental outcomes, so it cannot show that these methylation changes cause harm or that a test is clinically useful. The authors note that the functional impact of methylation depends on CpG site location, tissue specificity, and timing of exposure, which complicates interpretation.

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Do not conclude that NICU care causes lasting epigenetic harm or that methylation can be used clinically. Average total methylation did not differ between term and preterm infants, the sample was small, and the authors state that further research is needed before methylation is applied as a biomarker.