A baby who can't gain weight is disconcerting to any loving parent. According to HealthyChildren.org, a baby's weight increases steadily from birth. Babies in the fifth percentile of weight, based on the standardized age-to-weight chart, are categorized by the medical community as failure to thrive. Inadequate weight gain can stem from a number of issues ranging from environment to digestive and metabolic disorders. As with any medical issue involving a child, professional medical supervision and guidance is essential.
Conditions that Reduce Eating
Several medical conditions can prevent a baby from consuming enough food. Included among these conditions is an underdeveloped or abnormally formed tongue, throat or esophagus, which can reduce the baby's ability to suck or swallow her food, formula or breast milk. Severe acid reflux can make eating uncomfortable, which in turn causes the baby to eat less. Lung and heart conditions can make nursing or sucking exhausting, which leaves the baby too tired to continue eating, even when she's hungry.
Absorption and Digestion
Even when a baby appears to eat enough food, certain medical conditions can increase his metabolism or prevent him from absorbing the necessary nutrients, which can prevent him from gaining weight. Liver disease, celiac disease and cystic fibrosis are just a few of the conditions that could prevent him from absorbing calories and nutrients from his food, according to HealthyChildren.org. Conditions that raise a baby's metabolism to an unhealthy level include, but aren't limited to, hyperthyroidism, chronic infection and immune-deficiency disorders.
Inadequate Food Availability
A baby's tiny belly means she needs to eat nourishing food frequently and consistently throughout the day. Insufficient feeding can stem from a poor understanding of a baby's nutritional needs. Giving an older baby too much water or juice can create feelings of fullness and can lower her appetite. Another possible reason why food isn't available is poverty, which can cause parents to dilute formula or reduce the frequency of feedings.
Family and Food Environment
A distracting setting, a rushed caregiver or parent and a chaotic environment can prevent a baby from eating enough to gain weight appropriately. A baby who's distracted by the television, the dog and his older siblings may stop eating his food. A hurried caregiver may remove his plate without evaluating what he actually ate or encouraging him to eat more. Examining the routine and quality of care is essential when evaluating poor weight gain, reports the American Academy of Family Physicians.