Objective: To investigate whether the duration of exclusive breastfeeding and maternal body mass index (BMI) are associated with children's developmental status at the time of beginning elementary school.
Design and subjects: The subjects in the sample came from a longitudinal study on infant nutrition in Iceland. Food records were made once a month from birth to the age of 12 months, from which duration of exclusive breastfeeding could be determined. Mothers filled in The Icelandic developmental inventory for evaluation of motor and verbal development close to their children's sixth birthday (n = 85). Maternal self-reported weight and height was recorded. Information on socioeconomic factors was gathered by a questionnaire.
Results: Duration of exclusive breastfeeding, in months, was positively related to children's motor component (B = 0.5+/-0.5, P = 0.054) and to the total developmental index (B = 1.0+/-0.5, P = 0.044) at 6 y, adjusting for gender and socioeconomic factors (maternal and paternal education, and family income). Children's learning score was negatively related to maternal BMI (B = -0.5+/-0.2, P=0.047). An inverse association also appeared between maternal BMI and two out of the three developmental composite scores, that is, verbal component and the total developmental index (B = -0.6+/-0.3, P=0.049) and (B = -0.4+/-0.2, P=0.057), respectively. In multiple regression the developmental indexes were most strongly independently associated with maternal BMI (negatively) and infants' birth weight (positively).
Conclusion: Maternal BMI and duration of breastfeeding were associated with verbal and motor development of 6-y-old children, independent of socioeconomic factors. Birth weight was also an independent determinant for developmental scores.