It all started in 1962, when Dr. T. Berry Brazelton, a renowned pediatrician and child development researcher, conducted a study of normal healthy infants by asking their parents some questions about their infant’s crying routine. In this study Dr. Brazelton found that all infants went through a stage in their development where they cried increasingly more. This crying began at about 2 weeks, peaked around six weeks of age and began decreasing around 12-16 weeks (3-4 months of age).
Twenty-four years later in 1986, two other pediatric developmental pediatricians, Dr. Urs Hunziker and Dr. Ronald Barr replicated Dr. Brazelton’s study. Their research of normal healthy infants in Montreal, Canada found the exact same results as Dr. Brazelton had. There have been several other studies done since that validate this normal crying curve of infants in the first few months of age.
This is an important discovery because the assumption for years was that if your baby cried excessively they had "Colic"" leading parents and caregivers to believe there was something wrong or abnormal with their baby. Extensive research now tells us that all infants go through a stage of increased crying, although some may cry a lot more than others. This crying is not an indication that there is something wrong with the baby but rather a normal developmental stage in all babies lives. You’ll notice on the simplified graph to the right that the crying starts to increase at about 2 weeks of age, peaks in the second month of life and then gets less at about 4-5 months. It is very important to remember that all babies go through this but some cry a lot, 5 or more hours, and some far less, only 30 minutes in a day/night.
So, the question remains, how do we know crying is the reason a person becomes so frustrated that they shake an infant? Certainly, we know that many have confessed after they shook their infant saying things like “I just could not stand the crying anymore", or “He would not stop crying so I shook him.” Cases like these are an indication that frustration with crying is certainly a reason someone shakes an infant, but is it the primary reason?
