Keywords
colic, crying infant, fussy infant
Infant crying can be a sign of pain, distress, hunger, or fatigue and is interpreted by caregivers according to the context of the crying. The cry just after birth heralds the infant’s health and vigor. The screams of the same infant, 6 weeks later, may be interpreted as a sign of illness, difficult temperament, or poor parenting. Crying is a manifestation of infant arousal influenced by the environment and interpreted through the lens of the family, social, and cultural context.
Normal Development
Crying is best understood by the characteristics of timing, duration, frequency, intensity, and modifiability of the cry ( Fig. 11.1 ). Most infants cry little during the first 2 weeks of life, gradually increasing to an average of 3 hours per day by 6 weeks and decreasing to an average of 1 hour per day by 12 weeks.
Cry duration differs by culture and infant care practices. For example, Kung San hunter–gatherer infants, who are continuously carried and fed four times per hour, cry 50% less than infants in the United States. Crying may also relate to health status and gestational age. Premature infants cry little before 40 weeks gestational age but tend to cry more than term infants at 6 weeks’ corrected age. Crying behavior in former premature infants also may be influenced by ongoing medical conditions, such as bronchopulmonary dysplasia, visual impairments, and feeding disorders. The duration of crying is often modifiable by caregiving strategies.
Frequency of crying is less variable than duration of crying. At 6 weeks of age, the mean frequency of combined crying and fussing is 10 episodes in 24 hours. Diurnal variation in crying is the norm, with crying concentrated in the late afternoon and evening.
The intensity of infant crying varies, with descriptions ranging from fussing to screaming. An intense infant cry (pitch and loudness) is more likely to elicit concern or even alarm from parents and caregivers than an infant who frets more quietly. Pain cries of newborns are remarkably loud: 80 dB at a distance of 30.5 cm from the infant’s mouth. Although pain cries have a higher frequency than hunger cries, when not attended to for a protracted period, hunger cries become acoustically similar to pain cries. Fortunately, most infant crying is of a lesser intensity, consistent with fussing.
Colic
Colic often is diagnosed using Wessel’s rule of threes —crying for more than 3 hours per day, at least 3 days per week, for more than 3 weeks. The limitations of this definition include the lack of specificity of the word crying (e.g., does this include fussing?) and the necessity to wait 3 weeks to make a diagnosis in an infant who has excessive crying. Colicky crying is often described as paroxysmal and may be characterized by facial grimacing, leg flexion, and passing flatus.
Etiology
Fewer than 5% of infants evaluated for excessive crying have an organic etiology, with no known association with feeding method or family history of food allergy or atopy. The etiology of colic is unknown and is likely multifactorial in etiology. Since it is a diagnosis of exclusion, evaluation of infants with excessive crying is necessary in order to rule out other serious diagnoses.
Epidemiology
Cumulative incidence rates of colic vary from 5% to 28% in different studies that vary by definition of colic and method of data collection. There is no known association with gender or socioeconomic status. Concern about infant crying also varies by culture, and this may influence what is recorded as crying or fussing.
Clinical Manifestations
Decision-Making Algorithm 
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