 Cranial ultrasound CUS is routinely performed on preterm infants 34 weeks estimated gestational age EGA on day-of-life DOL 3 and again on DOL 7-10. Patients with Papile Grade II-IV intraventricular hemorrhage IVH will undergo serial CUS 1-3 times weekly for 21 days following IVH to monitor for post-hemorrhagic ventricular dilation PHVD. Using standardized CUS parameters Levenes ventricular index, Daviess diagonal anterior horn width and thalamo-occipital diameter, infants will be offered enrollment in the trial when their ventricular measures exceed the 97th percentile. Randomization to either low- or standard-threshold PHVD treatment will be performed by opening sequentially numbered, sealed envelopes. Envelopes will be prepared using a randomization schedule where allocations are assigned in a 1:1 ratio in blocks of 4 so that the desired 1:1 ratio will be maintained at periodic intervals in the study. 