Children are at highest risk for AHT when they are from 2 to 4 months old, because it is the period of most intense, inconsolable crying. All babies less than 1 year of age are at high risk for SBS/AHT because they cry longer and more frequently—and they are easier to shake than older, larger children. One study showed that educating parents about how to cope with inconsolable crying was associated with reducing AHT by over a third in children under 2 years of age (Wilson et al., 2021).
3.1 Triggers for Maltreatment
Perpetrators can be the father, stepfather, mother, or mother’s boyfriend. Female babysitters were a large, previously unrecognized group of perpetrators and are concerning because they more easily escape prosecution
The attacks tend to be unwitnessed and take place in the home. Because such attacks are usually caused by frustration with a baby’s crying, one prevention strategy includes never leaving the baby alone with someone who is easily irritated, has a temper, or has a history of violence.
Intimate partner violence is highly correlated with use of harmful parenting strategies, including shaking. People who have had a high number of adverse childhood experiences (ACES) are also more likely to abuse their own children. The connection between ACEs and questionable parenting approaches increases with each ACE. Men who had witnessed intimate partner violence (IPV), had a parent who was incarcerated, or who had been physically neglected as children, were more likely to consider shaking a baby to be acceptable (Clemens et al., 2020).
Other predisposing risk factors include: first pregnancy, younger than 24 years old or older than 40, full-time employment, living in an independent house or on a high-rise, economic difficulties, postpartum depression, delay of four months in seeking medical checkups (Latino et al., 2024).
3.2 Episodes of Crying
Inconsolable, long-lasting crying is the most common trigger for shaking a baby. In what has now come to be known as the “infant cry curve,” mothers reported gradual increases in their infants’ cry duration until 6 weeks, where crying and fussing had a “peak” average duration of 2.75 hours per day. The infant cry curve has since become widely recognized by parents and clinicians as describing a predictable pattern, peaking at 6 weeks, then declining steadily until 12 weeks (Vermillet et al., 2022).
Approximately 3% to 28% of otherwise healthy infants worldwide suffer from infantile colic, which is characterized by inconsolable crying, irritability, and screaming without any apparent cause (Bhatt and Kumas. 2023). As distressing as it is for exhausted caregivers, infantile colic is a benign and self-limiting condition that usually resolves between 3 and 4 months of age. However, it is often associated with maternal postpartum depression and SBS/AHT (Rosenthal and Hein, 2023).
Parents and caregivers report the crying as intense, long-lasting, and ear-piercing. It is especially distressing because the infant’s face may be flushed, the abdomen may be tense or distended, and the infant may arch his or her back in what appears to be agony. The causes of colic remain unknown, though colic accounts for 10% to 20% of visits to the pediatrician (Rosenthal and Hein, 2023).
Excessive crying has also been associated with early termination of breastfeeding, parental distress, and symptoms of parental depression. This fussing or crying usually decreases significantly after 8 to 9 weeks, though preverbal infants continue to rely on fussing and crying to communicate in the first few years of life (Vermillet et al., 2022).