Many times Lactation Consultants and other medical professionals hear a birthing parent ask, "What will my baby eat while I wait for my milk to come in?" The answer is almost always "The baby will have colostrum." This will often result in a perplexed look from the soon-to-be parents. So what is colostrum and how will it sustain your baby until your milk comes in?
Colostrum is a thick and sticky yellowish first milk that begins being produced by the pregnant body in the days or weeks before birth. It is often referred to as liquid gold, and some birthing parents may even leak colostrum before the baby is born. The amount of colostrum that is being produced is not abundant. But with a newborn's stomach only being the size of a cherry or holding about 5-7 ml it doesn't need to be very much. And even though it is small in quantity it is big in nutrients, antibodies, proteins, and carbohydrates. All the things that the baby needs to sustain them in the first few days.
Colostrum, however, isn't just the appetizer before the main course. Colostrum also has another benefit. One of its main purposes is to protect the baby from the effects of jaundice. While the baby is growing in the uterus their main organs are not 'on-line'. The cord and placenta are removing the baby's waste products out for the birthing parents organs to deal with. One of those is bilirubin. Bilirubin is a by-product from dead red blood cells that can build up in the baby's system after birth when the baby's liver is still too immature to manage the large volume it has to deal with. Baby's body excretes the by-product in their poop. The colostrum acts as a laxative, pushing everything out of baby's bowels. The substance is call meconium and is that black, dark greenish sticky poop that all parents are so excited to deal with. Once baby's poop begins to change color, specifically a more yellow mustard color, then jaundice isn't a concern. It is advisable that baby latch onto the breast in the first hour after birth and every 2-3 hours for the next 24-48 hours. This will help flush out the meconium and encourage your body to begin the process of producing your mature milk.
Around day 2-4 baby will decide they no longer want to feast on colostrum and will very rudely demand the next course on the menu, your mature milk. After cluster feeding for 12-24 hours, where baby feeds very very frequently, your mature milk will either slowly come in or your breasts will become engorged after a sleep. And now you can say "your milk has come in." If you do not get engorgement, you will see your milk begin to change color. From a thick yellow substance to a thinner white color.
So while you may not have what you would consider breast milk right after the baby is born you do have colostrum, and that's all baby needs for the first few days of their precious new life.