Secular Trend of Birth Height and Weight in a Population of Iranian Neonates during 1991 and 2011

The secular trend in growth is a well documented and common phenomenon in many developed and developing countries. In this study, we examined the secular trends in birth length and weight among Iranian neonates between 1991 and 2011.
This cross-sectional population-based survey conducted in 2014. Using multi-stage stratified cluster sampling, the birth weights and lengths of neonates born in Shahroud, Iran were collected from family health records. The mean birth weights and lengths were calculated for each year. Secular trends were analysed using linear regression models.
Among a random sample of 11,165 neonates, the mean birthweight of neonates during the investigation period changed from 3232.1 ± 444.1 g in 1991 to 3204.1 ± 436.9 g in 2011, and the mean birthlength changed from 49.5 ± 2.2 cm to 49.3 ± 1.9 cm. The mean birth weights and lengths between 1991 and 2011 were not significantly different; however, the mean birthweight decreased by 47.8 g between 1997 and 2001 as compared to that between 1991 and 1996 (P The mean birth length and weight of new-borns in Shahroud did not change significantly over the 21 years study period, but we found significant differences when looking at the 5-year intervals.