King's College London

Previous research has focused on differences in early life experiences that occur between families and their impact on children's development. However, less is known about the variations in early life experiences that occur within families. Here, 53 British mothers (mean age = 34.46 years; SD = 4.35) of newborn infants (mean age = 1.68 months, SD = 0.96) used a smartphone application (app) to repeatedly rate their wellbeing and support and to report their baby's and their own dietary and sleeping patterns (4 app alerts per week for 3 weeks; 12 assessments in total). We found that the app was a practicable tool for observing early life experiences, and that early life experiences differed on average to a greater extent within, rather than between families (59% versus 41% of the total variance). We also found preliminary evidence for meaningful associations among contemporaneous within-family variations in early life experiences.