This was originallly a Facebook post and due to its popularity I've turned it into an article. I've added in a couple of extra bits of information and updated it on the 1st May 2020....
During pregnancy prolactin (the hormone that helps make milk) is being produced. However, progesterone from the placenta stops it from working to full potential. This is actually a very clever design of Mother Nature (in my opinion) - while there is a placenta inside the womb there must be a baby, therefore there is no need to make large quantities of milk. It takes a lot of energy to grow a baby and make milk - so why 'waste' energy making milk when there is no baby needing to take it?
However, once the placenta is birthed (ie the baby is born) the prolactin can start working, but this can take up to 72hrs to reach full effect
There is only a small amount of colostrum available for the first few days - because the prolactin was preventing from working to its full potential during pregnancy only a very small amount of colostrum is being made.
But, THIS IS OK. Healthy, term babies do not need large quantities in the first few days after birth. Plus, in another clever design by Mother Nature, colostrum is packed full of protein and carbohydrates - this can sustain the baby long enough, until the quantity of milk increases and it starts to include fat and water.
They have this substance called ‘brown fat’ that can be used for extra energy if needed. They have basically been in training the whole pregnancy to be OK with just colostrum. This is also why almost all babies lose weight in their first 48-72hrs – they are using up this brown fat and the colostrum does not contain fat to make them grow
Studies have shown that a newborn’s stomach can only hold ~5-7mls at a time and in the first 24hrs a newborn may only take between 30 and 125mls of colostrum (that’s in total, over the whole 24hrs). But this is why they need to be fed frequently.
Colostrum is actually more about antibodies and food for bacteria!
Colostrum is high in protein, which does give the newborn some nutrients/energy, but its main purpose is actually to feed the bacteria that is going to colonise the baby’s gut. We all know that our guts are colonised with bacteria – this helps us digest food and keep us healthy (fun side fact - there’s more bacteria inside and on us, than we have cells!). In-utereo babies have no bacteria in their gut or anywhere else – during birth they are inundated by bacteria, from the mother’s vagina, anus, and skin. Colostrum contains a substance called oligosaccharides that are purely just food for the bacteria. They also get an 'injection' of antibodies so that they can cope with all the bacteria and viruses they are suddenly bombarded with on the outside
Colostrum has a mild laxative effect. Inside a baby’s gut does not move and so they have a substance called meconium collected in their intestines. Some babies do pass some of this in-utereo, but that is a different subject, but the majority do not. Getting colostrum signals the gut that it is time to start working. Once the milk starts changing from colostrum to ‘mature’ milk, the meconium will also change – from thick black to a ‘sludgey’ green and then to yellow.
There seems to be a myth that colostrum is not enough or is somehow not good – this just isn’t true. Yes, there will always be a small percentage of babies who need something extra to help them as they transition to life outside. But in the majority of cases colostrum is very good.
The most important rules of newborn feeding are to feed the baby frequently (this doesn’t necessarily need to be a large amount though) and watch their poo and weight gain. Newborns should feed a minimum of 8 times in 24hrs - 10/11 is actually the average. You cannot overfeed a breastfed baby.
The vast majority of babies will lose weight by day 3 - remember this is normal because they have lost the meconium and brown fat that they were born with. By day 5 they should be gaining weight and have regained their birth weight by 2 weeks.
Once the milk is in they should have at least 3 yellow 'splats' of poo per day up to 6 weeks - less may be ok but should be checked by a breastfeeding friendly health professional. After 6 weeks they may go longer between poos but they should always be easily passed.
If you have any