So let's talk about how milk production works in those early days, so that you can be more confident that your baby is satisfied.
You start producing the early milk, called colostrum, between 10 and 14 weeks of pregnancy. Colostrum is milk, but it's not the mature milk you'll see a few days after your baby is born. Rather, it's a highly concentrated, thick, golden liquid consisting mostly of protein, beta carotene, and antibodies. Colostrum is sometimes called "liquid gold" because it is so valuable to a newborn baby to help protect his tender new gut, support his undeveloped immune system, and prepare him for life outside the womb.
The presence of the placenta and the progesterone it produces keeps your milk volume low, so you won't produce mature milk until after your baby is born and the placenta is expelled. Your levels of prolactin - the hormone that tells your breasts to produce milk - are very high at the birth of your baby, but it's just floating around in your blood stream with no way to send the message until you start actually nursing a baby. The action of the baby suckling at your breast (or of a breast pump or hand expression) creates "prolactin receptors," places for the prolactin to attach within the breast so that the message to produce milk can be sent. The takeaway from this is simple: The more you nurse your baby in the first 3 days of life, the better your milk supply will be even months down the line.
Now, once the baby is born and the placenta detaches, your levels of progesterone, the hormone produced by the placenta that supports the pregnancy, drop, and you've started establishing prolactin receptors. This paves the way for the prolactin to do its job, and your body will begin producing more milk - and that milk will be the mature, watery, white substance we think of when we think of "milk."
It takes about 48 to 72 hours for your milk volume to increase. In the first two to three days of your baby's life, he does not need to eat much. Remember that he was being constantly fed by the umbilical cord while inside you, and his intestines are full of meconium - a greenish-black, tarry substance that coats the intestines. There isn't room for much food until the meconium is cleared out. Colostrum, along with all of its other amazing properties, acts as a laxative to help clear out that meconium. Your baby's stomach is very tiny at first and cannot hold more than about a teaspoon (5mL) of milk anyway, so it doesn't take much for him to feel full. Remember, in the last few weeks of your pregnancy, he was packing on fat stores to help him survive these first few days of life where he suddenly isn't eating much.
Though your baby isn't super hungry at birth, he will have a high need to suck. This high need to suck serves a few purposes. First, when the baby suckles at the breast, it stimulates the release of oxytocin, which helps the mother's uterus shrink back down and slows her postpartum bleeding. Second, as mentioned before, it helps set up receptors for the milk-production hormone called prolactin. Third, the sucking stimulates the baby's intestines to start moving out the meconium to make room for the milk. Finally, newborns find sucking comforting. Babies even suck on their hands inside the womb!
By about 72 hours after the birth, you should notice that your breasts feel fuller and are now producing something that looks a great deal more like "milk" than the colostrum did. Some women find they become extremely engorged literally overnight, while others notice a more gradual increase in volume. If your milk hasn't increased in volume by about 72 hours after birth, you may need to speak with a lactation consultant and/or your baby's pediatrician about providing supplemental donor milk or formula until you have a greater volume of milk available. It is important that your baby start eating so that he can grow.
Once the milk supply does increase, you'll want to know that your baby is getting enough to eat. You can monitor how much the baby is getting by counting diapers - what goes in must come out! A 3-day-old baby should have three wet diapers and three poops per day. A 4-day-old should have 4 and 4. A 5-day-old should have 5 and 5, and after that, there should be at least 6 pees per day and anywhere from about 3 to 6 or more poops. In order to be sure that your baby is really producing at least that many wet diapers, you need to check your baby's diaper at least that many times per day. If you're not sure how to tell if the diaper is wet, or you are concerned that your baby isn't wetting as often as he should, you can place a piece of tissue in a clean diaper. When you check the diaper, if the tissue is wet, then your baby has peed.
Another way to reassure yourself that your baby is getting enough to eat is to watch his growth. Your pediatrician will want to see your baby several times in the first two months of life. Your baby should be gaining at least half an ounce a day, if not more, and should be back up to his birth weight by the time he's 10 to 14 days old. Even if you don't get to weigh your baby often, you'll notice as he starts outgrowing his clothing and diapers, becomes heavier for you to hold, and starts to fill out.
If you're concerned that he's not taking in milk, you can do what's called a "weighted feed," where you weigh the baby hungry, then feed him, then weigh him again on the same scale with the same amount of clothing. This requires a sensitive baby scale that can measure in small increments. Many baby boutiques and lactation consultants will have scales like this available to do weighted feeds and to check your baby's growth. Typically, a newborn baby will take in about 2oz. of milk in a feeding, which you can see because he'll be 2 oz. heavier after feeding!
Finally, you can tell if a baby is getting enough by making sure he's not dehydrated. His eyes and mouth should be moist, skin should be smooth and not have dry patches, and the fontanel (the soft spot on top of the head) should not be sunken. He should not be lethargic or floppy, should have periods where he's awake and alert, and should wake on his own to eat. If you see orange urine crystals in his diaper or he has fewer than six pees in 24 hours after day 5 of life, call your pediatrician immediately. Dehydration in a baby can be very serious but is also very treatable.
If you have any reason to be concerned about your baby, don't hesitate to call your pediatrician. Trust your gut. If your baby is not himself, it doesn't hurt to have him looked at. Often the nurse can listen to your concerns on the phone and help you determine if the doctor needs to see the baby.
Remember that a newborn typically eats 12 or more times in a 24-hour period, but that doesn't necessarily mean he's eating exactly every two hours. He might eat three times in three hours, then sleep for three hours, then eat twice more in the next four hours, then sleep for two hours, etc. Watch the baby, not the clock, for when you should feed him next, and follow his cues.
The best way to ensure that your milk supply is healthy and your baby is well-fed is to simply nurse, nurse, nurse. Avoid artificial nipples such as pacifiers and bottles until at least three to four weeks of age, when breastfeeding should be well established. Have your baby's latch evaluated if you have any pain while nursing. Sometimes it may look like your baby is nursing well but he's actually not transferring milk efficiently. Listen for the sounds of swallowing and for a suck-swallow-breathe pattern. If your baby is sucking but not pausing to swallow or breathe, he may not actually be getting any milk, or not enough to trigger the swallow reflex.
Check out my videos on newborn nursing to see what it looks like (and sounds like!) when a tiny baby nurses!