<p>Increased time to surgery has been correlated with increasing cerebral fractional oxygen extraction without compensatory increase in cerebral blood flow in neonates with critical congenital heart disease (cCHD) suggesting an overwhelmed cerebral autoregulation system. Autoregulation analysis can provide precision targets such as optimal blood pressure but it remains unclear how autoregulation evolves in days preceding surgery. Our hypothesis is that longer wait times between birth and surgery are associated with increasing periods of impaired autoregulation. A retrospective observational study evaluating the time spent within optimal blood pressure (MAP_OPT) range identified by cerebral autoregulation analysis in full term newborns with cCHD awaiting neonatal surgery. Time domain autoregulation methods using continuous blood pressure and cerebral near infrared spectroscopy were employed to generate daily MAP_OPT and time with impaired autoregulation. Sixty subjects had a median [IQR (interquartile range)] of 5.2&#xa0;days [3.9–7.9] of recordings from birth to surgery. Subjects spent a median of 7.6%, [5.3–13%] with impaired autoregulation. Time within MAP_OPT decreases slightly within the first ten days of life when controlling for confounders. Subjects spent a mean (± standard deviation) of 40.8% (± 15.5%) of each day within MAP_OPT (51.3 ± 6.1&#xa0;mmHg) and a median of 28.1% [13.6–45.5] time below MAP_OPT. Mixed effects regression showed that subjects spent 1.93% less time each day within MAP_OPT range (<i>p</i> = 0.001) over time but there was no difference in time spent below MAP_OPT. Full term neonates with cCHD experience variable periods of impaired autoregulation throughout the pre-operative period and spend less time within MAP_OPT over that time. More work is needed to understand if autoregulation is a potential contributor to previously described association between longer wait time to surgery and increased white matter injury.</p>