Objective: To assess the most important sociodemographic determinants of age at introduction of complementary foods in infancy.
Design: A prospective birth cohort with increased risk of type 1 diabetes, recruited between 1996 and 2004. The families completed at home a follow-up form on the age at introduction of new foods and, for each clinic visit, a structured dietary questionnaire with 3 d food records.
Setting: Data from the Type 1 Diabetes Prediction and Prevention (DIPP) Project, Finland.
Subjects: A cohort of 5991 infants (77 % of those invited) belonging to the DIPP Nutrition Study.
Results: Sixty-three per cent of the infants were introduced to complementary foods, including infant formula, before the age of 4 months. The median age at introduction of infant formula was 1·5 months (range 0-18 months) and that of the first other complementary food 3·5 months (range 0·7-8 months). All sociodemographic and lifestyle factors studied were associated with the age at introduction of infant formula and/or first other complementary food. Female sex of the infant, being born in the southern region of Finland, living in a rural municipality, the presence of siblings, the mother or the father being a high-school graduate, high maternal professional education and maternal non-smoking during pregnancy predicted later introduction of complementary foods.
Conclusions: Compliance was relatively poor with the current recommendations for the age of introducing complementary foods. Small-sized young families with less well-educated parents were most prone to introduce complementary foods early.