Decide the feeding plan by matching the route to the baby's developmental stage. At 33 weeks and 1.5 kg the infant is moderately preterm and low birth weight, but moderate prematurity at this weight is generally compatible with feeding the gut, which is preferable to parenteral routes because it protects the intestinal mucosa and lowers infection risk. The deciding limitation is reflex maturity: the neural wiring that synchronizes sucking, swallowing, and breathing does not mature reliably until about 34 weeks, so a 33-week baby placed straight to breast or bottle is at real risk of aspiration. The solution is to keep nutrition enteral while sidestepping the immature reflex, which is exactly what gavage feeding through a nasogastric or orogastric tube accomplishes, ideally using the mother's expressed milk. Testing the other strategies confirms this. Relying on intravenous fluids, whether alone or paired only with observation, needlessly denies a stable baby the enteral feeds it can handle and the trophic benefits they bring. Total parenteral nutrition is held in reserve for the smaller, sicker, or gut-compromised infant who truly cannot be fed enterally, a description that does not fit this stable 1.5 kg baby. The route that feeds the gut yet respects the unready suck-swallow reflex is tube feeding. $33\text{ weeks} \Rightarrow \text{immature suck-swallow} \Rightarrow \text{tube feeds}$.\[\boxed{\text{Oral nasogastric tube / alternate oral route}}\]