Progesterone just happens to be one of the hormones that can have calming and sleep-inducing effects. A baby receives progesterone from the placenta at birth but the soothing effect from it generally wears off in about a week or two and it is also suggested that colic occurs if the infant does not produce enough progesterone on his own. In general, the studies surrounding this are mixed at best but they do indicate colic occurs less in breastfed infants because breastfed babies receive higher levels of progesterone.

Prostaglandin; which is a hormone that causes strong contractions of the intestinal muscle, has also been thought of as a culprit in colic. One study even showed the infants develop colicky symptoms when they were given prostaglandin therapeutically to treat their heart disease.

Colic occurs at an age and stage of an infant's life when he can do nothing at all to ensure his own comfort and amusement. It is the time when they are almost totally dependent on their caregivers for any type of stimulation at all. Is it possible colic begins to subside at around three months of age because that is when babies can finally see clearly and can begin doing things on their own that they may find soothing, such as finger sucking, eye contact, and waving their arms and legs around, which I think is so that the baby can release stress? At around three months of age most babies also develop a higher central nervous system maturity.