Familial factors more importantly modify the age of achieving motor developmental milestones than duration of breastfeeding amongst Polish children.

Breastfeeding in the first year of life is an important factor that may modify the child's later development.The aim of this study was to examine the association between the duration of breastfeeding and the time of achieving motor development of Polish children taking into account their familial background. The study material comprised 460 individuals including 252 boys and 208 girls aged 9 to 56 months who were born at term (37-42 weeks) selected in years 1993-1997. The investigated dependent variables were: first attempts of sitting, standing and walking (months). The independent variables were divided into: explanatory variable - the duration of breastfeeding, and other covariates - birth weight, the paternal and maternal age at the time of childbirth, maternal tobacco smoking during and after pregnancy as well as the parental level of education. The results of regression models after removing the prenatal and familial factors did not indicate a significant relationship between the duration of breastfeeding and sitting up (F = 0.03, p = 0.8569), standing up (F = 0.79, p = 0.3741) and walking variability (F = 0.20, p = 0.6568) in studied group of children. The results showed that parental age and education may affect the offspring's gross motor development, though effect sizes are small and directions of influence vary between fathers and mothers. The study underlines the importance of familial factors over the breastfeeding duration impact on time of developmental milestones.