Beneficial effects of betamethasone in the late preterm period are known (Gyamfi-Bannerman, C, et al NEJM 2016). The optimal time interval between betamethasone and delivery, however, is uncertain. Among women at risk of late preterm delivery, we sought to determine whether time interval (TI) between betamethasone and delivery is associated with neonatal adverse respiratory outcomes. This is a secondary analysis of a multicenter randomized trial to determine the effects of betamethasone in women at risk for late preterm delivery. The inclusion criteria for our analysis were singletons with no major anomaly, receiving betamethasone, with calculable TI between administration of last betamethasone dose and delivery. TI categories were: 1) ≤ 48 hours; 2) > 48 and ≤ 168 hours, and; 3) > 168 hours (7 days). Primary outcome was neonatal respiratory outcomes among the 3 TI groups. Primary and secondary outcomes are defined in the tables. Multivariable Poisson regression models with robust error variance were used to determine the association between TI and neonatal outcomes, while adjusting for confounders. Adjusted relative risk (aRR) with 95% confidence intervals (CI) were calculated, using TI > 48 and ≤ 168 hours as the referent group. Of the 2,831 women in the parent trial, 1,414 (50.7%) met our inclusion criteria. While 68.5% delivered in ≤ 48 hours, 15.3% were born > 48 and ≤ 168 hours and 16.2% at > 168 hrs. Factors significantly different among the three groups include: nulliparity, pre-pregnancy BMI, hypertensive disease, premature preterm rupture of membranes, number of betamethasone doses (1 versus 2), preterm delivery (gestational age < 37 weeks), labor type, and route of delivery. Among women who received betamethasone, the primary outcome was significantly less if delivery occurred > 168 hours, compared to > 48 and ≤ 168 hrs. Severe respiratory complications were also significantly lower if delivery occurred > 168 hours, compared to > 48 and ≤ 168 hours. (Table) Even when adjusted for rate of preterm birth, among women at risk for late preterm birth, the lowest rate of neonatal respiratory complication is when delivery occurred beyond 168 hrs (7 days).