Her heart is in the right place: an investigation of the ‘heartbeat hypothesis’ as an explanation of the left side cradling preference in a mother with dextrocardia

A majority of mothers, whether right- or left-handed, exhibit a preference to hold their babies to the left of the body midline. One of the earliest explanations for this finding proposed that babies were being held close to the mother's heart [Salk, L. (1960). World Mental Health, 12, 168–175]. Salk suggested that the foetus becomes imprinted on the sound of the maternal heartbeat in utero. This paper reports a left holding preference in a mother who has the heart positioned on the right rather than the normal left side of the body. Salk's ‘heartbeat hypothesis’ is not supported by the holding preference of the dextrocardiac mother, nor by the detailed patterns of holding in the control group.