Fetal macrosomia is a risk factor for the development of obesity late in childhood. We retrospectively evaluated the relationship between maternal conditions associated with fetal macrosomia and actual overweight/obesity in the European cohort of children participating in the IDEFICS study. Anthropometric variables, blood pressure and plasma lipids and glucose were measured. Socio-demographic data, medical history and perinatal factors, familiar and gestational history, maternal and/or gestational diabetes were assessed by a questionnaire. Variables of interest were reported for 10,468 children (M/F = 5,294/5,174; age 6.0 +/- A 1.8 years, M +/- A SD). The sample was divided in four groups according to child birth weight (BW) and maternal diabetes: (1) adequate for gestational age offspring (BW between the 10th and 90th percentiles for gestational age) of mothers without diabetes (AGA-ND); (2) adequate for gestational age offspring of mothers with diabetes (AGA-D); (3) macrosomic offspring (BW > 90th percentile for gestational age) of mothers without diabetes (Macro-ND); (4) macrosomic offspring of mothers with diabetes (Macro-D). Children macrosomic at birth showed significantly higher actual values of body mass index, waist circumference, and sum of skinfold thickness. In both boys and girls, Macro-ND was an independent determinant of overweight/obesity, after the adjustment for confounders [Boys: OR = 1.7 95 % CI (1.3;2.2); Girls: OR = 1.6 95 % CI (1.3;2.0)], while Macro-D showed a significant association only in girls [OR = 2.6 95 % CI (1.1;6.4)]. Fetal macrosomia, also in the absence of maternal/gestational diabetes, is independently associated with the development of overweight/obesity during childhood. Improving the understanding of fetal programming will contribute to the early prevention of childhood overweight/obesity.