I can't speak for newborns generally, but ours hasn't followed many consistent patterns so far. The one recurring behaviour that we have noticed is that the baby cries--sometimes to the point of being inconsolable-- between about 4PM and 7PM. There doesn't seem to be anything wrong with him, he's content in the morning and he generally sleeps well at night. The cause of these regular bouts of fussiness seem to be a mystery. Or maybe they're not.
I grew up being very familiar with the term "colic" because I myself was a colicky baby. My mother assured me that it was "no big deal", that I just needed to be held upright from 3PM to 9PM for the first couple of months of my life. Considering my mother had a toddler at the time and lived in an era when women did everything, I think this was a very big deal.
My mother always believed that my excessive crying was due to abdominal cramps. She formed this belief because I would pull my knees up to my chest while crying and the fact that I was an otherwise happy baby. I couldn't have been crying for nothing, could I? I always subscribed to this theory, assuming that the cramps were a result of a dairy sensitivity from the infant formula I was given.
Dr. Harvey Karp, author of the bestselling book, "The Happiest Baby on the Block", would disagree with my mother, and his reasons are persuasive. Dr. Karp points out that the theory that colic is caused by tummy trouble does not hold up for a variety of reasons, including the fact that colic is often much worse in the evening, despite the fact that babies eat and spit up throughout the day and night, and that colic is improved by rocking, holding and shhhing, when these actions have no curative effect on stomach issues.
I haven't been confident of much since I became a mother, but I am confident that when my instincts tell me something, they are probably right. When my baby has a crying frenzy in the evening, once I've fed him and changed him, my instincts tell me that he needs to be held and soothed. He gets gassy throughout the day and doesn't cry like that, so I really believe that it's more that just a sore tummy.
Dr. Karp's theory is that colic is a result of newborn's need for a so-called "fourth trimester". He says that some newborns aren't really emotionally ready to leave the womb for the first few months, and so baby's with more sensitive temperaments can't handle the drastic changes to their environment.
I don't know if my baby has colic, and I may never really know why he cries when I'd like him to sit contently while we eat supper. My heart tells me that he's just a little overwhelmed with the world around him and he needs my support to get through the next few weeks. So I tell him that everything is ok and I will be there for him as long as he needs me.