Background. The participants of European Longitudinal Study of Pregnancy and Childhood (ELSPAC) are women permanently resident in Brno, whose expected term of delivery corresponded with the prelimited period. In midpregnancy, 3327 of them %lled in two research questionnaires with data concerning their marital status, health, education, dwelling, their up-bringing and stress in childhood as the essential information for the study of birth weight and gestational age variations of expected newborns. Methods and Results. Sharing the flat with the parental generation, heating with solid fuel or gas and more smokers at home meant the risk for antenatal development of foetus. A certain influence seemed to have the number of rooms, too. Education of the mother-to-be as well as that of her partner and partly of her mother, too, determined the birth weight. To a certain degree, partner's position in employment and his health status played also a role. An important factor predetermining the birth weight and gestational age was the marital status of the mother: in the best situation were children boru in complet families and greatly handicapped were offsprings of single mothers not living with their partners. Conclusions. Small influence on the prenatal development had the medical history of mothers, character of the upbringing in their original families and presence stressogenic events occurring in their girlhood up to 18 years of age.

        Key words: birth weight, gestational age, risk factors, Social situation, medical history, stress, prospective study.