This is taken from the C.S. Mott Children's Hospital website.
How Do I Know My Baby Is Getting Enough Milk?
You can't see exactly how much milk your baby takes while nursing. However, you can tell whether breast-feeding is off to a good start if you know what to look for. The following patterns are typical of well-nourished, breast-fed babies during the first month of life.
1.You start producing milk abundantly 2 to 4 days after your baby is born.
If your baby seems hungry after most nursings or you do not think your milk has come in by 5 days after delivery, tell your baby's doctor and have your baby weighed.
2.Your baby latches on to your breast correctly and sucks rhythmically for at least 10 to 15 minutes at each feeding.
Your baby may pause sometimes while breast-feeding. However, he should nurse vigorously during most of the feeding. You should hear your baby swallow regularly while breast-feeding.
Allow your baby to remain at the first breast until it is well drained, so he will receive the rich, high-fat hind milk. When your baby starts to suck less vigorously, swallows less, or begins to doze off, you can burp him, change his diaper and arouse him to take the second breast. Generally, babies get more milk at a feeding by nursing at both breasts. Since the first breast gets drained better, begin each feeding on a different side. This way, both breasts will get about the same stimulation and emptying.
3.Your newborn nurses at least 8 times every 24 hours.
Nurse your baby as often as she shows hunger cues, such as waking from sleep, becoming alert, bringing a hand to her mouth, turning her head, or moving her mouth or tongue. Remember that crying is a late sign of hunger and a baby may not nurse well after crying too long. For the first few weeks, you can expect your baby to want food about every 1 1/2 to 3 hours, with a single longer stretch (up to 5 hours) between feedings at night. Newborns that feed fewer than 8 times in 24 hours or sleep through the night are not likely to get enough milk. At times you may need to awaken your baby to nurse. Some babies just don't demand to be fed as often as they should, especially in the first few weeks of life.
4.Your baby appears satisfied after nursings and may fall asleep at the second breast.
Breast-fed infants who appear hungry after most feedings -- who cry, chew their hands, or often need a pacifier after nursing -- may not be getting enough milk.
5.Your breasts feel full before each feeding and softer after your baby has nursed.
One breast may drip milk while your baby nurses on the other side. After the longest time between feedings at night, your breasts should feel particularly full.
6.Your baby's bowel movements look like cottage cheese and mustard by the 4th or 5th day of life.
Bowel movements that look like cottage cheese and mustard are called "milk stools." If your baby is still having dark meconium, green, or brown stools by 5 days of age, you should have your baby weighed to see if he is getting enough milk.
7.Your baby urinates 6 or more times a day once your milk has come in.
The urine should be colorless, not yellow. If it looks like the diaper has reddish brick dust on it after your baby is older than 3 days, your baby's urine probably is too concentrated and your baby may not be getting enough milk.
8.Your baby has 4 or more good-sized bowel movements each day.
Many breast-fed babies have a bowel movement every time they nurse during their first 3 to 4 weeks of life. If your newborn is having fewer than 4 bowel movements each day, you should have your baby weighed to see if he is getting enough milk.
9.Your nipples may be a little tender for the first several days of nursing, especially at the beginning of feedings. The discomfort should be nearly gone by the end of the first week of breast-feeding.
Nipple pain that is severe, lasts throughout a feeding, or continues more than 1 week after birth probably means your baby is nursing incorrectly. If your baby doesn't latch on properly to nurse, your infant may not be getting enough milk. If you do have very sore nipples, ask your infant's doctor to check your baby's weight and to refer you to a lactation consultant who can look at how your baby is nursing.
Two or three weeks after delivery you may notice the sensations associated with the milk ejection, or milk let-down, reflex.
Breast-feeding causes the release of the hormone oxytocin. This hormone causes the uterus to cramp. These "after-pains" with breast-feeding are more noticeable than any early breast sensations. They usually go away 7 to 10 days after the birth of your baby.
The sensations of the milk ejection reflex are a tingling, pins-and-needles, or tightening feeling in your breasts as milk begins to flow. When your milk let-down occurs, your baby may start to gulp milk. Milk may drip or spray from the other breast. You may find that just hearing your baby cry causes your milk to let down, even before your baby starts nursing. If you don't notice any signs of milk let-down, your milk supply may be low.
10.Once your milk comes in, your breast-fed baby should gain weight rapidly -- at least 1 ounce each day for the first couple months of life.
The only way to be absolutely certain that your baby is getting enough milk is to have your baby weighed regularly. If your baby is not gaining enough weight, your milk supply may be low or your baby may not be nursing effectively. Such breast-feeding difficulties are easier to overcome if you recognize and treat them early. Your baby's doctor can help develop a feeding plan tailored for you and your baby or can refer you to a lactation consultant.
And for formula milk, here's the article
http://www.babycentre.co.uk/baby/formula/howmuchmilk/
