The main causes are as follows.
Improper feeding: When infants eat too quickly resulting in too much air, or eat too much beyond their own digestive capacity, they can be stimulated to cause nausea and dry heaving.
Respiratory tract infections: such as acute laryngitis, bronchitis and pneumonia can also manifest as nausea and dry heaving.
Digestive tract disorders or immature or abnormal development of the cardia: the main manifestations are vomiting or spitting up milk, crying in discomfort, and possibly vomiting or swallowing food downwards.