Baby Rakesh weighed 3 kg at birth. By what age will this birth weight double?

Appeared in: JSSH Staff Nurse - 2019

Explanation

According to standard pediatric growth patterns, a healthy infant typically doubles their birth weight by the age of 5 to 6 months.
For an infant weighing 3 kg at birth, the expected weight at this milestone would be approximately 6 kg.
This rapid growth phase is a primary indicator of adequate nutrition and overall well-being in early infancy.

Option A: At 2 months, an infant is in a phase of rapid growth but has not yet had enough time to double their birth weight.
Option B: By 24 months (2 years), an infant's weight is expected to have quadrupled (4x), not just doubled.
Option D: At 36 months (3 years), a child's weight is typically about five times (5x) their birth weight.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Infant growth milestones: Weight gain as background academic context rather than a clinical decision trigger.
Monitoring weight gain is a fundamental nursing responsibility in pediatric care. It helps in assessing nutritional status, hydration, and overall health.
Deviations from these expected milestones can be an early indicator of 'failure to thrive' or other underlying health issues, prompting the need for further investigation and intervention.
What if? If an infant was born prematurely, their 'corrected age' (chronological age minus weeks of prematurity) would be used to assess growth milestones, so they might reach these weights later than a full-term infant.

How to Approach the Question

First, identify the key information in the question: the infant's birth weight (3 kg) and the specific milestone being asked about ('double').
This is a factual recall question based on standard pediatric growth and development knowledge.
Recall the common rules of thumb for infant weight gain: weight doubles by 5-6 months, triples by 1 year, and quadruples by 2 years.
Apply the 'doubling' rule to the question. The expected age is around 5-6 months.
Scan the options provided and select the one that best matches this timeframe.
Eliminate the other options by recalling the milestones associated with them (e.g., 24 months is for quadrupling).

Concept Tested & Keywords

Concept Tested: Infant growth milestones: Weight gain
Stem keywords: birth weight, double, age
Lead-in keywords: By what age
Clinical cues: Birth weight of 3 kg is a standard reference point for a healthy infant.

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E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 10-12

E6 Nutrition Kumud Khanna 2e p. 109-111

Practise the full JSSH Staff Nurse - 2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.