Your newborn baby seems to be growing so quickly. One day, he was as skinny as a string bean, now he’s a plump and round as a ball. He’s also developing new skills, including the ability to recognize your voice and face. Keep an eye on your baby as he grows. If he stops growing, that could be sign he’s having trouble absorbing nutrients or isn’t getting enough to eat.

The First 2 Weeks

Your baby will probably lose a few pounds in the first few days after birth. That isn’t a cause for alarm. He’s simply shedding excess fluid. Your baby should gain back any lost weight by the end of his second week. At the end of his first week, your baby may have a growth spurt. You’ll know if a growth spurt is happening, as he’ll want to feed more often or for longer lengths of time. Around week 2, his eyes should be developing, and he should be able to focus on objects that are about 1 foot away.

Weeks 3 and 4

Most infants gain between 5 and 7 oz. each week, according to the Mayo Clinic. By the end of the fourth week, your baby may have gained nearly 2 lbs. and may be about an inch longer than he was at birth. He may have another growth spurt around week three, in which case you’ll notice a hungrier, fussier baby. Usually the remaining piece of umbilical cord falls off by week four.

Weeks 5 and 6

Around week five or six, your baby may have developed the ability to smile. He’ll also be able to move a bit more smoothly than before, though you should still support his head when holding him, since the neck muscles haven’t quite caught up yet. He should gain about 1 lb. before the end of week six and may have grown another 1/2 inch.

Weeks 7 and 8

Your baby’s eyes and vision will continue to develop. Around the seventh week, he should be able to recognize different colors distinctly. He should also be able to see connect sounds with the objects they come from. His neck muscles should become much stronger as well. By the end of the eighth week, many babies can lift up their head to about 45 degrees, according to "Parents" magazine. He should have put an nearly another pound and another 1/2 inch in height by the end of week eight.