摘要：Birth weight is the somatometric measurement most commonly used as an indicator of the general health conditions of a population. Birth weight variation over time may reflect changes in the reproductive pattern of a country. In Spain the National Institute for Statistics (INE) has registered the weight at birth since 1981. In this paper seven categories of weight are considered (<1000, 1500-1999, 2000-2499, 2500-2999, 3000-3499, 3500-3999, and ≥4000 grams) for the period 1981-2002. The results obtained show that the estimated mean birth weight (MBW) has reduced following a lineal and constant tendency throughout the period studied: MBW = 3414,42 – 9,35 * (Year-1981). The frequency of low birth weight (<2500 g) among newborns has increased significantly in the same period, while the number of macrosom newborns (≥4000 g) has decreased. Although in Spain the first maternity as well as the average maternal age have increased birth weight has decreased. A variation in the proportion of mothers smoking during pregnancy may have influenced the fall in mean birth weight. The temporal evolution of these and other variables that may be related to weight is discussed and a comparison with other countries is made.
