Table 2. Summary of key findings mapped onto COM-B and TDF domains.

COM-B Behavioral component	TDF domain	Key findings
Capability Psychological	Skills	Several parents described being unable to settle their baby and would choose to co-sleep or try to stay awake all night
	Knowledge	The majority described sleep practices consistent with guidance and being able to ask questions of practitioners; some reported that safer sleep advice was not followed, and was not discussed with practitioners; Some parents with older children felt that advice generally did not go into detail about updated guidance
	Memory, attention & decision processes	Understanding risks and why practices protected infants was seen as an important part of safer sleep messaging
Opportunity Social and environmental	Social influences & environmental context & resources	Some parents report informing their own parents about updated guidance. The majority were able to source sleep equipment
Motivation Reflective	Beliefs about capabilities	The majority felt they had autonomy; however, several parents described how their decisions were influenced by social workers, and that they were keen to demonstrate this ‘compliance’ with safer sleep guidance
	Optimism	Mothers who reported co-sleeping relied on practical measures such as pillows to prevent them from rolling onto their babies, or babies from rolling out of bed, and adjusting their own sleeping position or style to make it ‘safer’ for their baby
	Beliefs about consequences	Many parents described using a cot and never co-sleeping due to fear of harming their baby, and that getting the baby to sleep in a cot was an important aspect of establishing good habits and routines; Several parents reported propping up mattress to elevate the baby’s head when they were ill
		Several parents described how they felt more able to monitor their baby while co-sleeping; those mothers who did co-sleep described themselves as light sleepers or hyper aware of their babies when sharing a sleeping space with them
	Goals	Decisions to co-sleep were framed around being able to take better care of their baby; none of the mothers were breastfeeding
Motivation Automatic	Emotion	Those parents who co-slept reported that doing so gave them a closer bond with their baby, reduced their anxiety, or provided them with better sleep