With very preterm deliveries, the decision to institute intensive care, or, alternatively, to start palliative care and let the baby die, is extremely difficult, and involves complex ethical issues. The introduction of intensive care may result in long-term survival of many infants without severe disabilities, but it may also result in the survival of severely disabled infants. Conversely, the decision to withhold resuscitation and/or intensive care at birth, which is an option at the margin of viability, implies allowing babies to die, although some of them would have developed normally if they had received resuscitation and/or intensive care. Withholding intensive care at birth does not mean withholding care but rather providing palliative care to prevent pain and suffering during the time period preceding death. The likelihood of survival without significant disabilities decreases as gestational age at birth decreases. In addition to gestational age, other factors greatly influence the prognosis. Indeed, for a given gestational age, higher birth weight, singleton birth, female sex, exposure to prenatal corticosteroids, and birth in a tertiary center are favorable factors. Considering gestational age, there is a gray zone that corresponds to major prognostic uncertainty and therefore to a major problem in making a "good" decision. In France today, the gray zone corresponds to deliveries at 24 and 25 weeks of postmenstrual age. In general, babies born above the gray zone (26 weeks of postmenstrual age and later) should receive resuscitation and/or full intensive care. Below 24 weeks, palliative care is the only option offered in France at the present time. Decisions within the gray zone will be addressed in the 2nd part of this work.