Present or absent: risks and protective factors of sudden infant death syndrome (SIDS) in the Zambian context.

Background: Despite a reduction in sudden unexplained infant death (SUID) in high-income countries, the incidence of SUID and the prevalence of its risk and protective factors remain poorly understood in Zambia due to limited research. We aimed to describe the infant sleep positions and sleep environments in an urban Zambian population to gain a better understanding of modifiable risk factors for SUID. Methods: We used antenatal, birth, and postnatal data from the Zambian Infant Cohort Study, a prospective birth cohort, to describe infant sleep practices in Chawama, a densely populated peri-urban community in Lusaka, Zambia. In addition to the longitudinal cohort data, we collected cross-sectional data on infant sleep practices and environmental risk factors associated with SUID during the 20-week study visit using a structured questionnaire. Results: We collected data from 596 caregivers and 605 infants. Overall, sudden infant death syndrome accounted for 8.3% (n/N = 3/36) of deceased infants. However, given the limited number of cases, this estimate should be interpreted with caution. Only 6.4% of caregivers attained an education beyond secondary school, and a significant proportion of infants (20.2%) had low birth weights, with 10.7% of infants confirmed by ultrasound as preterm. Furthermore, 96.5% of infants were placed to sleep on their side or in a prone position, and 98.2% of infants shared a sleep surface with their caregiver. Breastfeeding, a protective factor, reduced from 99.2% on day six to 43.1 at the 24-week visit. Conclusions: Both modifiable (bed-sharing and prone sleep position) and non-modifiable risk factors (low birthweight and prematurity) of SUID are prevalent in this low socioeconomic setting in Zambia. Public health strategies to prevent SUID need to be innovative and culturally congruent in addressing modifiable risks in settings where there is a lack of space.