Situation: The nurse holds a weekly well-baby clinic at a Barangay Health Station (BHS) for infants who come for immunization, growth monitoring, and feeding counseling. The nurse reviews the growth record of a 6-month-old girl born at term: Age | Weight | Weight-for-age z-score Birth | 3.2 kg | 0.0 2 months | 5.0 kg | -0.2 4 months | 6.3 kg | -0.1 6 months | 6.5 kg | -1.0 The mother reports that the baby has had no illness. How should the nurse interpret this pattern?

The trend matters more than a single value. She gained only 0.2 kg from 4 to 6 months, and her z-score dropped from -0.1 to -1.0, so her curve is flattening even though she is still above -2 z. Without illness, the most common causes are feeding problems, such as early water or foods replacing breast milk, so her feeding must be assessed now.

Interpretation of the growth pattern

The most important step in reading a growth chart is to examine the trajectory of the weight-for-age z-score over time, not just the absolute weight at a single visit. In this infant, the z-score moved from 0.0 at birth to -0.2 at 2 months and -0.1 at 4 months, then dropped to -1.0 at 6 months. Although the value remains above the conventional cutoff of -2 for underweight, the downward shift of nearly one full standard deviation between 4 and 6 months signals that the rate of weight gain is slowing. A single z-score above -2 does not rule out growth faltering when the trend is clearly flattening.

The actual weight gain reinforces this concern. From birth to 2 months, the infant gained 1.8 kg; from 2 to 4 months, she gained 1.3 kg; but from 4 to 6 months, she gained only 0.2 kg. This deceleration is consistent with the definition of faltering growth, which refers to a slower rate of weight gain than expected for age and sex ^[2]. It is not simply the normal physiologic slowing that occurs as an infant becomes more active around 4 months; the magnitude of the drop in z-score is too large to attribute to that alone.

Because the mother reports no illness, the most likely contributors are nutritional or feeding-related. When an infant has no acute or chronic disease, inadequate caloric intake is the leading cause of a flattening weight curve. Common feeding problems at this age include early introduction of water, diluted formula, or low-calorie complementary foods that displace breast milk or formula. These issues can be identified and corrected only through a structured feeding assessment, which should include a detailed history of what the infant is actually consuming, the frequency and duration of feeds, and any recent changes in feeding practices ^[1][4].

Age	Weight	Weight-for-age z-score	Interpretation
Birth	3.2 kg	0.0	Appropriate for gestational age
2 months	5.0 kg	-0.2	Normal gain
4 months	6.3 kg	-0.1	Stable trajectory
6 months	6.5 kg	-1.0	Faltering weight gain

Key point! Doubling birth weight by 6 months is a rough milestone, but it is not sufficient to declare growth normal when the z-score is falling. This infant has doubled her birth weight, yet the pattern is still concerning because the rate of gain has slowed sharply.

Watch out! Referral to a supplementary feeding program is appropriate when an infant is underweight, typically defined as a weight-for-age z-score below -2. This infant is not yet below that threshold, so the priority is not referral but rather a feeding assessment to identify and correct the problem before the z-score falls further.

The rationale for acting now rather than waiting is supported by the observation that once growth faltering is recognized, accumulated nutrient deficits can be difficult to recover . Early identification and prompt correction of feeding problems offer the best chance of restoring a normal growth trajectory. The nurse should assess the feeding pattern immediately, provide targeted counseling, and schedule close follow-up to monitor the response.