evidence: WHAT ARE THE RISKS OF OXYGEN? Too much or too little oxygen can be harmful. If the cells in the body get too little oxygen, energy production decreases. With too little energy, cells may not work well and may die. Your baby may not grow properly. Many of the developing organs, including the brain and heart, may be injured. Too much oxygen can also cause injury. Breathing too much oxygen can damage the lung. For babies who are born very prematurely, too much oxygen in the blood may also lead to problems in the brain and eye. Babies with certain heart conditions may also need lower levels of oxygen in the blood.