During which developmental period do 90% of SIDS cases occur?

The correct choice is that 90% of Sudden Infant Death Syndrome (SIDS) cases occur during the first six months of life. Research indicates that the risk of SIDS is highest in infants during this window, particularly between the ages of one and four months. During this time, infants are still developing critical physiological functions, which increases their vulnerability.

SIDS typically manifests in infants who are otherwise healthy, and many factors contribute to this phenomenon, including sleep environment and sleep position. It's essential for caregivers to be aware of these high-risk months to implement safe sleeping practices that can significantly lower the incidence of SIDS.

While SIDS can occur in the first year and even the second year of life, the overwhelming majority of cases are concentrated in the earlier months; thus, this highlights the importance of monitoring infants closely during this crucial period.