From the Guidelines
Infants typically gain 1.5 to 2 pounds per month and grow 1 to 1.5 inches in length each month during the first two months of life, with an estimated energy cost of growth of around 175 kcal/day at 0-3 months 1.
Key Growth Metrics
- Average weight gain: 1.5 to 2 pounds per month
- Average length increase: 1 to 1.5 inches per month
- Head circumference increase: approximately 0.5 inches per month
- Energy cost of growth: around 175 kcal/day at 0-3 months 1
Growth Patterns and Expectations
Growth rates can vary significantly between individual babies, with some growing steadily while others experience growth spurts. Parents should expect their baby to regain their birth weight by 10-14 days of age after an initial weight loss of 5-10% in the first few days after birth. The use of World Health Organization (WHO) growth charts is recommended for children under 24 months, as they provide a standard for healthy growth and development 1.
Clinical Implications
Clinicians should be aware of the differences between the WHO and CDC growth charts, as well as the potential advantages and limitations of using each chart 1. The WHO charts are based on a breastfed infant population, and slower growth among breastfed infants during ages 3-18 months is considered normal 1.
Monitoring Growth and Development
Regular monitoring of an infant's growth and development is crucial to identify any potential issues or abnormalities. Clinicians should use the WHO growth charts to screen for possible abnormal or unhealthy growth, and be aware of the energy cost of growth and its implications for infant nutrition 1.
From the Research
Infant Growth in the First Two Months
- Infants typically experience rapid growth during the first two months of life, but the exact amount of growth can vary depending on several factors, including nutrition and overall health 2, 3.
- Studies have shown that infants with failure to thrive, a condition characterized by inadequate weight gain or growth, may require interventions such as formula supplementation or changes to breastfeeding practices to support healthy growth 2, 4.
- Research has also highlighted the importance of adequate nutrition, including protein and energy intake, for supporting infant growth and development 4.
- While there is limited direct evidence on the exact amount of growth infants experience in the first two months, studies suggest that average weight gain for breastfed infants is around 150-200 grams per week, and average length increase is around 2.5-3.5 cm per month 3.
- It's worth noting that individual growth patterns can vary significantly, and factors such as gestational age, birth weight, and overall health can influence growth rates 5, 6.