Lifestyle habits, including diet and physical activity, that deviate from the recommendations during pregnancy and early childhood may eventually increase the risk for obesity and other lifestyle-related diseases in both the mother and the child. High prevalence of obesity among pregnant women and children in Finland suggest that novel means to support health-promoting lifestyle habits among these target groups are needed. Thus, the aim was to assess lifestyle habits of pregnant women and children with reference to the national recommendations. Another aim was to study the effects of a health app for improving lifestyle habits during pregnancy and to develop a short method for the assessment of diet quality in children for dietary screening and health promotion purposes.

Weight, diet quality and physical activity during early and late pregnancy as well as the efficacy of the health app on improving these lifestyle habits were investigated in 1038 Finnish women (study I). Further, food supplement use during pregnancy was studied in 1804 women from Finland, Italy, Poland and the United Kingdom (study II). Diet quality was assessed with a validated index in 766 preschool-aged children (study III) and diet with food diary and food frequency questionnaire in 266 elementary school-aged children (study IV). Moreover, a tool for assessing diet quality in elementary school-aged children was developed (study IV).

The results indicated that the diet quality and physical activity levels were suboptimal in majority of the pregnant women. Most of the women consumed vitamin D and folic acid supplements during pregnancy, but adherence to the recommended doses was low. No benefits on the use of the health app were seen in diet quality and weight gain. However, physical activity level among app users decreased less likely compared with app non-users over the pregnancy course, indicating that the benefits of the app use may arise from maintenance of physical activity. The results also showed that diet quality was suboptimal in most of the preschool and elementary school-aged children; especially the consumption of vegetables, fruits and berries was low. The developed stand-alone index depicted diet quality in elementary school-aged children as defined in the dietary recommendations. Thus, it may be used as a valid tool in e.g. dietary screening.