The weight of a new born baby tends to fluctuate a bit during the first few days of birth. In fact, the weight may dip by 5% which is considered normal. The baby gradually puts the weight again in a span of 15-20 days.
In the first few months, a baby should at least weigh 115-220 grams. After 6 months, weight may increase drastically.
After a year, a baby weighs more than double of the birth-weight. If the weight is more than that, then it is better to consult a doctor.
For optimal weight, health experts recommend breast feeding every couple of hours (nearly 7-12 times a day). In some cases, when the baby gains weight too fast, mothers may worry whether it could cause obesity. As breast milk isn't an unhealthy source of calories, mothers don't need to worry.
The weight of a baby fed with other substitutes may vary from the weight of a baby who is fed solely with breast milk.
How to know whether a baby gets enough milk? Well, it is better to observe whether the baby feels satisfied after consuming the milk. Also, a baby tends to sleep after feeling satisfied.