Blue baby syndrome can refer to conditions that cause cyanosis, or blueness of the skin, in babies as a result of low oxygen levels in the blood. This term has traditionally been applied to cyanosis as a result of: Both of these conditions cause cyanosis, or a bluish discoloration of skin or mucous membranes. Normally, oxygenated blood appears red and deoxygenated blood has more of a blue appearance. In babies with low levels of oxygen or mixing of oxygenated and deoxygenated blood, the blood can have a blue or purple color, causing cyanosis.