From the Guidelines
Normal weight gain after birth for very low birth weight infants should aim for 17-20 g/kg per day to prevent growth failure. This recommendation is based on the most recent and highest quality study available, which suggests that this rate of weight gain is necessary to prevent dropping across weight centiles 1. For other newborns, they typically lose 5-10% of their birth weight in the first week, then regain it by 7-10 days of age, with some studies suggesting that birth weight should usually be regained by 7-10 days of life 1. After that, healthy babies generally gain weight at a rate that allows them to track along their own growth curve.
Some key points to consider when evaluating normal weight gain after birth include:
- The initial postnatal weight loss, which is a normal phenomenon
- The importance of regaining birth weight by 7-10 days of age
- The need for individualized growth tracking, as weight gain patterns can differ based on factors such as feeding method, genetics, and individual factors
- The recommendation for very low birth weight infants to aim for a weight gain of 17-20 g/kg per day to prevent growth failure, as supported by the evidence from 1.
It is also important to note that common recommendations suggest an average time to regain birth weight by about 7-10 days after birth, but some infants may take longer, and pathology should be carefully excluded and the feeding regime checked in these cases 1.
From the Research
Normal Weight Gain After Birth
- Newborns typically lose weight after birth, with a mean weight loss of 6-8% of birth weight by Day 2-3 2
- The nadir of lost birth weight usually occurs on Days 2-4 after birth, with most newborns regaining their birth weight by 10-14 days 2
- Studies have shown that weight loss greater than 7% may be a normal phenomenon among breastfeeding newborns, with 56% of healthy, full-term newborns losing more than 7% of their birth weight 3
- Newborns who lost more than 7% of their birth weight had a lower exclusive breastfeeding rate at 2 weeks of age, with a rate of 60% compared to 82% for those who lost less than 7% 3
Weight Regain Patterns
- After the weight nadir is reached, most newborns gain weight at a similar pace, with a mean daily weight gain of 1.1% of body weight 3
- Newborns who lost less than 7% of their birth weight gained weight at a rate of 1.2% per day, while those who lost more than 7% gained weight at a rate of 1.0% per day 3
- By 10-14 days after birth, 50% of newborns are at or above their birth weight, with 14-24% not yet back to their birth weight depending on delivery mode 4
Factors Influencing Weight Gain
- Gestational weight gain has a positive linear relationship with birth weight, with studies showing that mothers who gain more weight during pregnancy tend to have heavier babies 5
- Delivery mode can also affect weight loss patterns, with newborns delivered by cesarean section tend to lose more weight and take longer to regain their birth weight compared to those delivered vaginally 4, 6