In binary logistic regression analyses with adjustment of gestational age, birth weight, sex and antenatal steroid use, the odds ratios of composite morbidities including BPD (≥moderate) and IVH (Gr ≥ 3) were significantly increased, and the odds ratio of without composite morbidities was significantly reduced in initial T4 levels of <4.5 ng/dl and/or f T4 < 0.9 ng/dl, but the odds ratios of mortality and ROP requiring laser therapy was significantly increased only in initial T4 levels of <2.5 ng/dl and/or f T4 < 0.5 ng/dl (Table 5). The gene discussed is CD4; the disease is bronchopulmonary dysplasia.