A previously healthy 4-month-old infant was brought to the ED late on a Sunday afternoon by his father, who reported that his son had been crying hysterically since the previous evening. The father stated that the infant was well until he awoke crying in his crib around midnight. Since then, the baby had not slept for more than 20 minutes uninterrupted and had not breastfed as usual due to the persistent crying. According to the father, the patient had been a “good baby” since birth, eating well and even sleeping through the night for the past month; specifically, his son’s continual crying was not typical of his usual behavior.
There was no known trauma, fever, congestion, cough, vomiting, or diarrhea at home, and the father confirmed the patient had been making wet diapers throughout the day. The baby had received his 4-month vaccines and, according to his pediatrician, had been following a normal growth pattern.
As the patient’s father related his son’s history, he appeared exhausted and extremely anxious, pacing the room as he spoke and trying unsuccessfully to quiet the baby. He stated that the patient’s mother, who was at home in bed with mastitis, was afraid their son had become ill because she had breastfed him while she had a fever. The father confessed that he was concerned that their older son, a rambunctious 2-year-old who shares the same room as the patient, may have accidentally done something to harm the baby unbeknownst to him or his wife.
In relating the history, the infant’s father was almost tearful as he admitted that he and his wife felt completely overwhelmed and helpless that they were not able to soothe or comfort the patient.
While often the healthiest of patients seen in the ED, infants with unexplained, prolonged crying are challenging to evaluate and discharge—especially in the care of distraught parents. The following review is intended to provide a basis for understanding the scope of normal crying in infants, how and if to diagnose infantile colic in the ED, and how to avoid missing common pathology requiring acute management in the infant with new, unexplained crying.
Normal Crying: How Much Is Too Much?
During the first 3 to 4 months of life, infants cry more than at any other time. Developmental pediatrician Harvey Karp, MD, dubs the first 3 months of an infant’s life as the “fourth trimester,” during which period the baby yearns for the calming acoustic and tactile sensations of the womb. He notes that crying in this fourth trimester is merely a response to the abruptly distinct stimulation of the outside world.1 Just as each baby tolerates these new sensations differently after birth, and is soothed in her or his own measure, each parent too has a different perception and tolerance of an infant’s crying—making for a clinical parameter that is difficult to clearly assess.
What, then has been established as the upper limit of normal for crying in infancy? In the 1960s, Brazelton’s studies defined normal crying as 1 hour and 45 minutes per day at age 2 weeks; 2 hours and 45 minutes at age 6 weeks; and less than 1 hour per day by age 12 weeks.2 A more recent meta-analysis reinforces Brazelton’s criteria, indicating that the mean duration of crying is approximately 2 hours per day during the first 6 weeks of life and decreasing to a daily mean of 72 minutes by age 10 to 12 weeks.3
As the caregiver’s report of the duration of crying is often subjective, more emphasis has been placed on evaluating patterns of newborn crying by defining what is excessive. Infantile colic, or excessive crying in an otherwise healthy baby, is classically defined as fussing or crying lasting more than 3 hours per day and occurring on more than 3 days per week in a baby who is gaining weight and is otherwise well.4 Severe colic is further described as the persistence of the crying pattern for more than 3 weeks. When using this “rule of 3s,” excessive crying is estimated to be present in 1.5% to 11.9% of the infant population. There are, however, many other definitions of what constitutes excessive crying, including the more inclusive and subjective definition of colic as “intermittent, unexplained crying during the first 3 months of life that reaches a point where the parents complain about it.”5
Depending upon the definition utilized, as many as 43% of infants experience excessive crying.6 What is more uniformly accepted in the extensive literature on infantile colic is the observation that crying because of colic is concentrated during the hours of 3:00 pm to 11:00 pm and is associated with infant behaviors such as clenched fists, back-arching, passing gas, grimacing, and flexing legs, as well as with maternal anxiety.1,2,7,8