Case Scenario

A couple brought their six-month old daughter to my office for a routine well-child examination. I saw immediately that the infant did not look healthy. The mother stated that she thought everything was going well. On persistent questioning, however, she acknowledged that her infant looked very thin and said that she was concerned about the 0.45-kg (1-lb) weight loss that had occurred since her daughter's examination at four months of age. Indeed, my small patient had fallen off the growth curve for weight.

This infant was the product of a normal full-term delivery with no complications and no maternal infections. Her birth weight was 3,660 g (8 lb), and she had been discharged from the hospital less than 48 hours after birth. The infant consumed 44 oz daily of formula containing iron and ate rice cereal and stage-1 baby foods without difficulty. Additional history indicated normal health and developmental milestones. The history indicated that a two-month old male sibling had died of rotavirus infection when the family lived in Germany.

The physical examination was normal except for wasted appearance, multiple skin folds in the diaper area and clearly visible ribs. All laboratory values were normal except for very dilute urine with a specific gravity of 1.001.

At prior well-child examinations, the infant had been in the 50th to 75th percentile for weight and length, and about the 90th percentile for head circumference. These indicators had all been drifting slowly downward and, at this six-month examination, the infant was at the 25th percentile for head circumference, 5th percentile for length and below the 5th percentile for weight.

Between the two- and four-month examinations, the mother had weaned the infant from breast milk to formula. The parents said they were using a powdered formula, adding one scoopful to a bottle and filling it with water to the 8-oz level. The mother filled a large jug with two scoops of formula and water to last for the eight hours that the infant was at day care.

According to the package instructions, the correct method for mixing the formula is to use one scoopful to every 2 oz of water. On questioning, it was evident that the parents had not read the instructions. They said they had added the powder to the bottle or jug in the same way they did when mixing powdered fruit drink for their own consumption. The illustration on the formula can depicted one scoop being added to one baby bottle—which is just what the parents did! They had not been trying to save money by using less powder. They expressed tremendous remorse for the harm they could have caused their infant.

I discussed with the parents the correct way to mix the formula and the importance of reading directions. At a follow-up examination three weeks later, the infant had gained almost 1,816 g (4 lb).

Commentary

In this case, a full-term infant who weighed 8 lb at birth and was initially in the 75th to 90th percentile for weight and length at prior well-child examinations, grew somewhat slowly until four months of age when she was just above the 50th percentile. Over the next two months, she lost 1 lb, which caused her to fall below the 5th percentile by six months of age. Using the National Center for Health Statistics growth charts, her weight at four months was approximately 6,250 g (13 lb, 12 oz), and at 6 months was less than 6,800 g (14 lb, 15 oz). Normally, infants gain approximately 20 g (0.7 oz) per day during this period. This infant was 1,600 g (3 lb, 8 oz) below her expected weight at six months of age.

The obvious explanation for this dramatic growth faltering was caloric deprivation. The formula, which had been mixed at approximately one-fourth the recommended concentration, was providing approximately 35 kcal per kg per day, far less than the 110 to 115 kcal required for normal growth. Although this infant was eating some solid foods, most of the calories obtained by infants of this age are in liquid form.

Relative slow growth from birth to four months of age is fairly common for large babies and some breast-fed infants.¹ In this infant, the dramatic decrease in weight corresponded to weaning from the breast to the over-diluted formula and the attendant sharp drop in caloric intake. The infant's good catch-up in growth (4 lb in three weeks, approximately 85 g [3 oz] per day, or four times the average weight gain for age) establishes caloric deprivation rather than occult illness as the cause of this child's weight loss.

Careful analysis of the growth chart raises an interesting question. At four months, the infant's length was at or above the 50th percentile (62 cm [24¼ in]); at 6 months, it was at the 5th percentile (approximately 61.5 cm [24¼ in]). It is unlikely that the infant actually shrank, but it seems that linear growth stalled completely. Normally, acute undernutrition results in a rapid decrease in weight with a more gradual decline in linear growth, causing a child to initially appear wasted (low weight for height), followed weeks or months later by stunting. In this case, however, the infant's weight-for-height appears to be normal. This pattern of growth would suggest a nonnutritional cause, such as hypothyroidism; however, the rapid catch-up in growth that occurred when adequate calories were provided essentially rules out this cause. It is possible that the very severe, sudden caloric deprivation may have accelerated the process of stunting. Stunting also occurs as a symptom of emotional deprivation (psychosocial dwarfism).²

It is of great concern that the parents did not seek medical attention sooner for the infant's weight loss. A normal four-month-old infant suddenly deprived of calories would exhibit behavior changes that would be hard to ignore, such as irritability, inconsolability and, as hunger persists, withdrawal, listlessness, stiffness when being picked up and visual “scanning” of the environment. These behaviors would not be subtle and would quickly become a source of alarm to most parents, leading to worried calls to the physician. That these parents were not alarmed enough to call their physician suggests that they were oblivious to the infant's distress. Effective parenting skills require sensitivity to an infant's affective cues. The absence of such sensitivity in this case is a cause of great concern.

A possible explanation lies in the curious history of the sibling who died at two months of age. It is highly uncommon for infants living in developed areas of the world to die of rotavirus infection; it is possible, therefore, that this infant's death was also caused by a lack of parental sensitivity to illness, which may have resulted in a delay in seeking help. Parents sometimes respond to the death of a previous child by becoming overly anxious about and excessively vigilant with succeeding children. Sometimes they respond by becoming detached, as if they have become incapable of investing love in a child who might also, in their view, die. Could a failure of parental commitment have caused these parents to remain oblivious to the distress of their infant of these parents.

It is also significant that apparently no other adult who had contact with the infant directed the parent's attention to this obvious problem. Grandparents or other family members typically step in to help inexperienced parents with parenting challenges and to correct perceived parenting errors. Other community members might also provide this sort of social support. In this case, however, no one came to the aid of the infant. That the day care staff colluded in providing inadequate feedings and failed to provide a warning suggests poor-quality day care.

Physicians should always consider the possibility that parents may be illiterate. It has been shown that most parents attending a typical pediatric clinic were unable to read and comprehend most of the parent information pamphlets available.⁴ Illiteracy is not obvious to casual inspection and may be difficult to detect through simple questioning. Use of a standardized reading test using a medical word list (e.g., REALM) can be helpful in assessing parental reading ability.⁵ While most instructions are written at about a seventh-grade reading level, interpreting them requires the ability to understand information presented in tabular form, a more demanding task.

The infant's rapid weight gain once the problem was identified is encouraging, but there may still be reason for ongoing concern. Malnutrition during the first six months of life has been linked to subsequent cognitive delays.² Early developmental intervention to improve parenting skills and the quality of infant stimulation might ameliorate some of these effects. This child is clearly at risk, and the physician should not wait for firm evidence of developmental delay before making a referral for early intervention.

The apparent lack of parental sensitivity to the infant's needs might suggest the need for a referral or report to the county child protective services agency for investigation of possible neglect. With the infant recovering weight well, however, it is doubtful that a referral would result in action by the agency. One possible benefit would be that the family's history would be on the agency records in case of any future incidents. On the other hand, many families move frequently, and county records do not follow them. The most important intervention, therefore, is for the physician to assure close and ongoing follow-up with this family. If they were to stop coming to appointments or following through on referrals for early intervention or other services, a referral to a child protective services agency would become necessary.

Further investigation of possible parental disengagement and lack of social support combined with appropriate interventions (e.g., therapy, social work consultation) could reduce the risk for long-term behavioral and developmental problems. This infant will benefit from the physician's ongoing concern for and vigilance about her care.