The aim of this study was to estimate, by geographic origin, the average situation of pregnant women who recently immigrated into the Paris area, using weight gain during pregnancy and infant birth weight. The clinical files of 559 pregnant women who attended the antenatal clinic at the Lariboisière Hospital (Paris) in 1997 and gave birth in this same hospital were analyzed. The mothers had immigrated from North Africa, Sub-Saharan Africa, Sri Lanka, China and metropolitan France. The successive body mass indexes were calculated for each woman, as well as the increase of this index during the first semester of gestation, until the third trimester and during the entire gestation. Averages in studied communities were compared with those of the non-immigrant population attending the same hospital department. The birth weights of infants from the different communities were compared with those of children born to non-immigrant mothers. Women from the various communities studied (with the exception of the Turkish community) showed a lower gestation weight gain than non-immigrant French women. Independently of the pregestational weight, weight gain during pregnancy accounted for 20% of the initial weight among women from North Africa, Turkey and China who gave birth to children whose birth weight was not significantly different from that of the non-immigrant French children. The mean weight gain corresponded to 15.8% of the pregestation weight in Sub-Saharan women and 18% in Sri Lanka women. Birth weights of children in these two communities were significantly lower than the French reference population. Compared with the weights observed in their original country, the frequency of low birth weight was lower and the mean birth weight was higher. Women coming from North Africa, Sub-Saharan Africa, and Asia who recently immigrated into France gave birth to children of satisfactory birthweight. The number of low birth weights decreased to the frequencies observed in their original countries. Irrespective for their reasons for immigrating, immigrant families living in France have newborns with a sufficient birth weight to allow satisfactory growth.