The aim of our study was to assess the extent to which families followed recommendations, issued by the German society for sleep medicine, for the prevention of sudden infant death syndrome (SIDS) during night-time sleep. Analyzing longitudinal data from a birth cohort located at the University Children's Hospital Regensburg in Bavaria (Germany), we determined data regarding the infant's sleep location, sleep settings and body position, and exposure to environmental factors. Data were collected in a structured interview after birth and by standardized questionnaires at 4 weeks, 6 months, and 1 year of life, respectively. The majority of 1,400 surveyed infants (94% at 4 weeks) were reported to sleep in the parents' sleeping room during the first months of life. While the most common furniture was a bedside sleeper (used by 48%), we also observed a considerable proportion of families who regularly practiced bed-sharing and, for 16% of infants, the parents' bed was the default sleeping place. 12% of infants were still put regularly in the prone position. The vast majority (87%) of the infants were breastfed at some timepoint and 17% lived in a household with one or more smokers. Although most parents implemented many SIDS recommendations, our analysis illustrates a considerable gap between recommendations and intentions after birth on the one hand and actual implementation in real life on the other. The number-one deviation from the current SIDS guidelines during night-time sleep was bed-sharing with an adult.