Figure 2:

Restricted cubic spline models showing adjusted probabilities of ratios for primary outcomes (BPD, NDI) and primary outcome combined with death by categories based on age of first initiation of steroids. Dots are the adjusted probabilities of the outcome. Solid lines indicate the boundaries of the 7-age categories of steroid initiation and dashed line indicates reference group (4 weeks). Odds ratios are adjusted for private insurance status, antenatal steroids, gestation age, birthweight, small for gestational age, sex, days of high frequency and/or conventional ventilation (HFV/CV) in first week of life, fraction of inspired oxygen on day 7, and center as a fixed effect. Additionally, the NDI model was also adjusted for birth year to account for changes in the evaluation through time (changes in target age for follow-up window and addition of motor component).