Health benefits of physical activity during pregnancy include reduced risk of excessive gestational weight gain and conditions such as gestational diabetes, preeclampsia and preterm birth. The ongoing CRoatian Islands Birth Cohort Study (CRIBS) is the first cohort study in the South-Eastern Europe with an aim to assess the prevalence of risk factors (biological, environmental and behavioral) for the Metabolic Syndrome in populations from Dalmatian islands of Hvar and Brač and coastal Split city with its surroundings. At the time of writing, Over 350 pregnant women and 220 of their newborns have been involved in the study. Here we present the preliminary results of testing the association of mothers` self-estimated physical activity during pregnancy with newborns` anthropometric characteristics (birth weight, length and head circumference) using the data from questionnaires and obstetric records of 116 mother – newborn pairs. The difference in weight-at-birth was detected between newborn girls whose mothers were from Low vs. Intensive physical activity categories, as well as from Moderate vs. Intensive physical activity categories. In addition to that, the significant difference in weight-at-birth and height/length-at-birth was detected between newborn boys whose mothers were from Moderate vs. Intensive physical activity categories (p<0.01). No association between self-estimated level of physical activity and mothers’ body mass index was found. For women with normal pregnancies, light occupational activities do not cause problems with the fetal growth rate, but the same was not reported for women who maintained high-intensity activities