AbstractIn Patan Hospital, Kathmandu, 4600 single live births were analysed concerning birth weight in relation to gestational age. At term, the median birth weight of females was 2900 g and of males 3010 g. Compared with Norwegian newborns, the birthweights of Nepali babies were lower for all corresponding gestational lengths. The differences increased with gestational age. Fundal height was lower in Nepali than in Norwegian pregnant women for all periods of pregnancy. An increase in the differences between Norwegian and Nepali women was also noted. Hematocrit values of Nepali women who did not take supplementary iron, correspond well to findings in Norwegian women without iron supplementation. Only a slight degree of hemoconcentration was noted towards term. For Norwegian women with iron supplementation the hematocrit values were much higher, with a tendency towards hemoconcentration near term. In Nepal the average woman probably has small iron stores, and without iron supplementation the hematocrit values will remain low throughout the pregnancy. The high altitude does not seem to cause hemoconcentration in pregnancy to a greater extent than at lower altitude. Hemoconcentration is therefore not a major causative factor of the lower birth weights.