The period of purple crying is a philosophy that believes crying, even bouts of unconsolable crying, is a normal developmental behavior in infants. Adherents believe that all babies go through this period starting at two weeks of age and lasting through 3-4 months. Some babies have a harder time than others.
I do not believe that bouts of unconsolable crying are normal for any baby. That circumstance would strongly indicate that birth trauma created soft-tissue strain compromising their nervous and other systems.
My mentor, Dr. Viola Frymann, published a research paper of 1,250 newborns in the 1960s. She found that 88% of the infants had craniosacral restriction (Frymann, V. Relation of disturbances of craniosacral mechanisms to symptomatology of the newborn: Study of 1,250 infants. Journal of the American Osteopathic Association. 1966: 1059-1075).
If we can identify this fascial tightness at birth and work it out during the first day of life, then babies will not generally have unconsolable crying, thus minimizing shaken baby syndrome. Do babies cry? Yes when they are hungry, wet, and then occasionally. But all babies should be happy most of the time.
My goal is for every newborn to be checked and treated. Parents need to leave the hospital with a calm and relaxed baby who can breathe well, nurse well, digest well, poop well, and nap well. These functions are the qualities of a happy baby.
Pediatricians need to understand that fascial strain is a big deal in their clinical practice. They need to step outside their technology, drug, and surgery box and open to the structural healing aspects of infants and children. They need to realize that happy babies and children are the rule.