Is supplementation necessary?
The answer is relatively simple; it depends on how baby is doing at the breast. At home, diaper output can give you an idea of how things are going. Ultimately, weight gain is the best indicator.
A newborn’s first poops, meconium, are tarry black. Colostrum helps to push the meconium through the first 2 days. As milk production picks up, baby’s poops will turn to dark green/brown, then light green, then mustard yellow around the 4th to 5th day. Seedy or curd textures are normal.
Babies will typically have 1 meconium poop the first day, 2 the second day, 3 transitional brown/green diapers larger than a US quarter on the third day, 4 brown/green to yellow credit-card sized diapers the 4th day, and 4-6 yellow poop diapers of the same or larger size the next couple of weeks. Around 2 months of age the number of poop diapers may decrease but the amount of poop in each one increases.
Once full milk production has started up--your milk has “come in”--baby should start gaining around an ounce (30g) per day; some babies will gain even more.
When breastfeeding is going well, a baby will often regain to birthweight by the end of the first week. But as long as they regain birth weight by 2 weeks postpartum and continue on an upward trend, they are likely going to be okay.
In the last half of the first month, most babies gain around 8-9oz (240-270g) per week.*
In the 2nd month, the rate of weight gain peaks at around 7-10oz (210-300g) per week. After this, the numbers drop by an ounce (30g) each month through 6 months.*
From 6-12 months this number slows down even more: 7-16oz (210-480g) per month during months 7-8 and 4-13oz (120-390g) per month during months 9-12. The range is quite wide; what’s most important is that your baby’s growth curve remains stable and doesn’t drop off.*
The range of weight gain above is based on babies in the 25th to 75th percentiles. Babies who are gaining above this range on exclusive breastfeeding are simply in a higher growth bracket. Those who are gaining below the range should be assessed more closely.
If baby is not gaining well, and especially if they also seem hungry a lot of the time or sleep too much and don’t eat often enough, they may not be taking in enough milk to support good weight gain. This might be due to low milk production, but it could also be that you’re able to make enough milk but your baby is having trouble getting it out. If baby is unable to remove enough milk from the breast to gain appropriately, then supplementation may be necessary, at least for the moment. That may be hard for some parents to hear, but baby’s nutritional need right now must take priority.
*Sources: WHO Multicentre Growth Reference Study Group. WHO Child Growth Standards: Growth Velocity Based on Weight, Length and Head Circumference: METHODS and Development. Geneva, Switzerland: World Health Organization; 2009. Riddle SW, Nommsen-Rivers LA. Low milk supply and the pediatrician. Curr Opin Pediatr. 2017;29(2):249-256.