Impact of antenatal glucocorticosteroids on whole-genome expression in preterm babies

Aim To study the impact that using antenatal steroid to treat threatened preterm delivery has on whole-genome expression. Methods A prospective whole-genome expression study was carried out on 50 newborn infants, delivered before 32weeks gestation, who had been exposed to antenatal steroids, including 40 who had received a full antenatal steroid course. Seventy infants not exposed to antenatal steroids formed the control group. Microarray analyses were performed five and 28days after delivery, and the results were validated by real-time PCR. The study was conducted between September 2008 and November 2010. Results Twenty thousand six hundred and ninety-three genes were studied in the infants' leucocytes. Thirteen were differentially expressed 5days after delivery, but there were no differences at day 28. Four genes related to cancer or inflammation were up-regulated. Nine genes were down-regulated: six were Y-linked and associated with malignancies, graft-versus-host disease, male infertility and cell differentiation and three were associated with pre-eclampsia, oxidative stress and chloride/bicarbonate exchange. Seven gene pathways were up-regulated at day five and only one at day 28. These were associated with cell growth, cell cycle regulation, metabolism and apoptosis. Conclusion Antenatal steroid therapy affects a limited number of genes and gene pathways in leucocytes in preterm babies at day five of life. The effect is short-lived, but long-term effects cannot be ruled out.