From the Guidelines
Healthy babies typically gain about 4 to 8 ounces per week during the first 6 months of life. This rate of growth is essential for proper development as infants need to double their birth weight by around 5 months of age 1. The amount eaten per feeding will increase ~1 oz per month and plateau at ~7–8 oz per feed, which supports the expected weekly weight gain in ounces for a baby 1.
Some key points to consider when evaluating a baby's weight gain include:
- Whether the baby is breastfed or formula-fed, as breastfed babies often gain weight more slowly after the first 3 months compared to formula-fed infants
- The baby's overall health and growth curve, which can be assessed by a pediatrician
- Factors such as sleep and physical activity, which can also influence growth rates, with recommendations including 14–17 h of quality sleep for infants 0–3 months and ≥ 30 min of tummy time spread throughout the day 1
It's essential to note that weight gain patterns can vary significantly between individual babies, and if you notice your baby isn't gaining weight according to these general guidelines, consulting a pediatrician is crucial as they can assess whether your baby's growth is appropriate based on their specific growth curve and overall health.
From the Research
Expected Weekly Weight Gain in Ounces for a Baby
- The expected weekly weight gain in ounces for a baby is not directly stated in the provided studies. However, we can look at the average daily weight gain and calculate the weekly weight gain.
- According to the study 2, the weight gain per day was approximately 39.7 ± 9.3 g for exclusively breastfed infants, 39.5 ± 9.4 g for mixed-fed infants, and 39.0 ± 9.5 g for exclusively formula-fed infants.
- To convert grams to ounces, we can use the conversion factor: 1 ounce = 28.35 grams. Therefore, the average daily weight gain in ounces would be:
- Exclusively breastfed infants: 39.7 g / 28.35 g/oz ≈ 1.4 oz/day
- Mixed-fed infants: 39.5 g / 28.35 g/oz ≈ 1.39 oz/day
- Exclusively formula-fed infants: 39.0 g / 28.35 g/oz ≈ 1.38 oz/day
- To calculate the weekly weight gain, we can multiply the daily weight gain by 7:
- Exclusively breastfed infants: 1.4 oz/day × 7 days ≈ 9.8 oz/week
- Mixed-fed infants: 1.39 oz/day × 7 days ≈ 9.73 oz/week
- Exclusively formula-fed infants: 1.38 oz/day × 7 days ≈ 9.66 oz/week
Factors Affecting Weight Gain
- The studies suggest that feeding mode and type of milk can affect infant weight gain. For example, bottle-feeding and formula milk have been associated with rapid weight gain 3, 4.
- Breastfeeding has been shown to be negatively associated with rapid weight gain 4.
- Other factors such as maternal pre-pregnancy BMI, infant birth weight, and maternal education can also influence infant weight gain 5.