Weight loss in a baby can be a sign of a serious underlying disorder and can lead to developmental problems if left unchecked. Normal babies should gain weight over the course of their first month and should have regained any early weight loss by two weeks of age, according to Kellymom. Neonatal weight loss at 1 month of age requires immediate treatment, either through hospitalization or through home treatment under a doctor's recommendation.
Weight loss seen in an infant at 1 month old is often described as failure to thrive. This designation may also be given to babies who have slow weight gain that is not adequate to maintain healthy development. Any weight loss in the first week of life should be made up by 1 month of age and the infant should be growing normally by this point. Failure to thrive at 1 month old indicates the presence of an underlying problem that should be addressed as soon as possible.
Normal Weight Changes
A normal, healthy infant should gain weight over the course of his first month of life, although weight loss in the first week of life is normal for most babies. Some babies lose up to 10 percent of their birth weight during the first 7 days of life, although a weight loss of 5 to 7 percent is more common. The degree of weight gain after the first week depends on the individual baby, but in general a pediatrician likes to see weight increasing steadily without large jumps or drops. One guideline sometimes used by hospitals is that a baby should gain 1/4 oz. each day for each pound of weight he weighs, according to MedlinePlus.
Babies who lose weight instead of gaining weight are at risk for severe physical and mental developmental delays. According to Merck Manuals, about 50 percent of children who fail to thrive early in infancy end up having permanent mental damage that causes a delay in the acquisition of verbal skills and may cause social and emotional problems later in life.
Malnutrition due to inadequate amounts or types of food, such as cow's milk instead of infant formula or breast milk, is a common underlying cause of weight loss in a 1-month-old infant. Weight loss may also stem from nursing problems in a breastfed infant, such as an improper latch that causes the baby to not get enough milk during a feeding or a low milk supply in the mother. Sometimes failure to thrive occurs because of a physical problem that impacts feeding or the absorption of food. Examples include cleft palate, gastroesophageal reflux or intestinal malabsorption. Infection may also cause the baby difficulty in digesting food or a loss of nutrients and fluids through diarrhea or vomiting.
In severe cases of weight loss in a 1-month-old infant, hospitalization might be necessary. The infant might need intravenous feeding and fluids while doctors determine the underlying cause and attempt to treat that problem. For infants who have only lost a small amount of weight slowly over the course of the first month of life, the baby's pediatrician may recommend home methods to increase weight gain. Frequent scheduled high-calorie feedings can help reverse weight loss in many cases.