Hi there we talked the other day ? yesterday about your cold I believe?
So your baby is 4 days old. Is your wife a first time mom?
I also read your earlier question today and I have a different take on the breast milk/formula thing.
So while I wait to see if you come on to chat let me give you some thoughts on bfeeding (I am somewhat passionate about this topic as it is one of my favorites!!). Breastfeeding is by far the most nutritious and healthy milk your baby can take. Formula pales in comparison although it can provide the nutrition a baby needs in a composition similar to breastmilk it can never provide the baby specific things that your wife produces especially for your child in her milk. Milk composition is actually different with each baby! There are some many other "things" in bmilk that formula lack including mainly immune compounds that are the best studied that provide direct protection against illness via antibodies and in other ways as well. We know from good evidence that Bfed babies are healthier in many ways including less risk of bacterial infections like ears,pneumonias, less risk for hospitalization initially, less risk of getting GI bugs (this one lasts for a few years actually), less risk later on for obesity (lots of thoughts on why), diabetes (probably a direct result of the obesity thing but may be more to it than this).....in short getting breast milk for as long as you can is good for you as a baby. We recommend 6 months to a year of exclusive (not using formula as well) breastfeeding for optimal benefits.
This said....breastfeeding is hard especially for a first time mom and even between different babies born to one Mom, some feed well some don't!
There is often inadequate support to help her in the "how" and also lack of support in keeping her breastfeeding as popular culture still supports bottlefeeding, it's really hard to work and breastfeed at the same time....you have to pump, it seems like unless you stand your firm ground and staunchly say I will breastfeed it is really hard to continue!
At 4 days her milk is likely not in yet if this is your first child, or just in if you have other kids. The time at breast suckling is the only thing that will directly influence how much she makes.....it is supply and demand....the more milk removed (by baby is best as it comes with lots of good hormonal input from mom which helps to stimulate the milk supply, or by pump if need be).
The initial milk removed is in fact not really milk but called colostrum and is extremely rich in immune benefits to the baby but short on volume. Thus almost all breastfed babies are "hungry" initially and it is this frequent demand at the breast that fuels milk production. It is totally true that formula fed babies will eat and then sleep up to 2-3-even 4 hours in the newborn period unlike bfed babies that tend to eat every 2-3 at the most hours. This of course although looking attractive right now as you are not used to sleep deprivation comes at the cost of future sleep savings later when your child is sick!!
If her breasts are not full yet (she will know when this happens) and she is a first time mom it will happen today or tomorrow. She will all of a sudden look like she got implants and leak. She needs to latch the baby at every sign of hunger and not use formula. You will know if your baby is OK by how much comes out the other end in terms of pee and poop. If the baby is not getting enough the pee can have an orange tint and is scarce but if you have a wet diaper every feed you are totally fine (I believe you guys have been supplementing with formula thus today your baby should be fine in terms of hydration). You should have increasing #s of poops daily as well. In a few days if you haven't been yet you will go to the pediatrician to see the babies weight. Most breast fed babies LOOSE weight in the intial stages and have up to 12 days to regain their birth weight. This is normal and not at all scary. Formula fed babies regain weight quickly but as I mentioned I do not view this as a good thing. I believe that supporting breastfeeding is one of the most important things I can do for a baby/mom pair in the newborn period and this rarely involves using formula.
If she has milk because she feels it and it is dripping it is possible the babies latch is off. There are many good pictures on the web of a wide mouth latch (the babies mouth should be as open as possible to get nipple + a lot of areola (the brown part) in its mouth....think of biting an apple. If Mom has pain with latch (happens almost to everyone although it could work better if we did a better job in the hospital helping Moms get started) the latch is off and could be improved to help your baby get the milk out better and also help Mom have less pain. You should see a lactation consultant if this is what is going on. As pedis we SHOULD also know how to help with this but often it takes a long time to get it right and really most doctors don't have the time or the know how to help. The sooner you see one the better as this is the critical first week.
Try this site from the La leche league http://www.llli.org/faq/positioning.html
Mom needs to drink plenty of water and sleep whenever she can and most importantly not give up or get frustrated by your hungry baby. Once they together get the breastfeeding thing it will all blow over and what she will feel is triumph and a sense of accomplishment. Her hormonal state makes dealing with a squalling baby who she feels she is not feeding well enough HARD and can even make her feel depressed. Rub her feet, bring her food and water, when it looks like the latch won't work take the baby from her and calm the baby down for her. Pacifiers are not recommended until the baby can latch well just in case it interferes with the latch but as you are already using a bottle it may be something to try to soothe the baby if they just need to suck!
Baby signs of hunger include being awake, sucking on lip, fingers, anything!!, smacking lips etc... crying is a late sign of hunger and often it will be hard to calm a crying baby enough to latch well unless you can fool them!
I hope that this helps. I will be on line for a few more hours write back with a response!l