What are the potential causes of uncontrollable crying in a 2-week-old infant?

Causes of Uncontrollable Crying in a 2-Week-Old Infant

At 2 weeks of age, uncontrollable crying is most commonly a normal developmental phenomenon that is just beginning its crescendo toward the peak at 6 weeks, though you must systematically exclude serious organic causes before attributing it to normal infant crying or early colic. 1

Normal Developmental Context

• Crying begins in the first month of life and increases progressively until peaking between 2-4 months of age, making a 2-week-old infant at the early phase of this normal developmental curve 1
• This represents the typical onset period, with crying episodes beginning around 1 month of age 1
• Understanding this timeline is critical because crying is the most common trigger of abusive head trauma, and almost all parents of infants who suffered abusive head trauma had previously sought help from their physician for their infant's crying 2

Serious Organic Causes to Exclude First

Red Flag Features Requiring Immediate Investigation

The American Academy of Pediatrics specifies concerning features that mandate workup 1:

• Bilious vomiting (suggests intestinal obstruction)
• Gastrointestinal bleeding
• Consistently forceful vomiting (if occurring about 5 times daily, consider gastroesophageal reflux) 3
• Fever
• Lethargy
• Hepatosplenomegaly
• Abdominal tenderness or distension

Metabolic Derangements

Perform serum glucose, calcium, and magnesium testing immediately, as hypoglycemia, hypocalcemia, and hypomagnesemia are common provoked causes of excessive crying and jitteriness that require immediate reversal 4

Trauma

Fractures or other trauma should be considered as a potential cause, particularly given that this is the peak age for abusive head trauma risk 1, 4

Maternal Substance Exposure

Obtain a comprehensive maternal drug history, as neonatal withdrawal has increased 10-fold in recent years 4:

• Opioids cause withdrawal in 55-94% of exposed neonates
• SSRIs present with tremors, irritability, and jitteriness within hours to days, lasting 1-4 weeks
• Benzodiazepines cause tremors and jitteriness with onset from hours to weeks, potentially lasting 1.5-9 months
• Caffeine causes jitteriness at birth, lasting 1-7 days
• Cocaine/stimulants produce neurobehavioral abnormalities including tremors and hyperactivity, typically on postnatal days 2-3 4

Common Benign Causes (After Excluding Above)

Normal Infant Crying Pattern

• In the majority of cases (>95%), no underlying organic cause is found, and the crying represents normal developmental behavior 5
• Up to 20% of parents report a problem with infant crying or irritability in the first 3 months of life 3

Early Infantile Colic

Infantile colic is diagnosed using the "Rule of Threes": paroxysms of inconsolable crying for more than 3 hours per day, more than 3 days per week, for longer than 3 weeks in an otherwise healthy infant 1

• At 2 weeks, the infant may be showing early signs but hasn't yet met the 3-week duration criterion
• Behavioral signs include leg raising and gas passing, typical manifestations of gastrointestinal dysfunction 1

Cow's Milk Protein Intolerance

Cow's milk proteins appear to be associated with the prevalence of infantile colic in a significant number of cases 6:

• Consider a 2-4 week trial of maternal dietary allergen elimination (milk and eggs) in breastfed infants 1
• Switch to extensively hydrolyzed formula if cow's milk protein intolerance is suspected in formula-fed infants 1

Critical Safety Counseling

This is the peak age for abusive head trauma risk, with crying being the most common trigger 1:

• Almost 6% of parents of 6-month-old infants admit to smothering, slapping, or shaking their infant at least once because of crying 1
• Counsel parents explicitly that it's safe to put the baby down in a safe place and take a break if overwhelmed 1
• Implement the Period of PURPLE Crying education program, which improves mothers' knowledge about crying and behavioral responses 2

Management Approach for Normal Crying

First-Line Interventions

Gentle motion, rhythmic movement, and white noise can calm the overstimulated infant 1:

• Avoid overstimulation from excessive tactile, visual, auditory, and kinesthetic stimuli 1
• Kangaroo care is an efficient method for preventing, minimizing, and halting crying 7
• Other effective interventions include swaddled holding, a pacifier, sugar water, heartbeat sounds, and reduction of external stimuli 7

Parental Support Strategies

Parents should remain calm and serve as an "emotional container" for the infant's strong emotions 2:

• Establish protective routines using visual and verbal cues for mealtimes and sleep times 1
• Implement "time-in" or special time (10-30 minutes of child-directed play) to strengthen parent-child connection 1
• Use distraction techniques such as games, music, or deep breathing to help the infant regulate emotions 1

Common Pitfalls

• Never use proton pump inhibitors—they are ineffective and carry risks including pneumonia and gastroenteritis 1
• Don't dismiss crying without metabolic workup in a 2-week-old, as this is too early to confidently diagnose benign colic
• Recognize that repeated stress without adequate support makes children progressively more vulnerable to future stressors, not more resilient 2
• Adults who are socially isolated may lack standards for comparison of their child's behaviors or resources for themselves, which can exacerbate stress and increase risk for abuse 8