Background: The actual Swedish growth references are based on a cohort born 1974.
Objective and hypotheses: Due to secular changes there is need for new height references.
Method: Material: Height measurements from birth to adult height (AH) in a cohort of healthy, Nordic and born full term 1990, 20.796 from 1647 boys, 19.202 from 1501 girls were used (ALL) and compared to both a subgroup with puberty close to mean (PHV ±0.25 years) of 3.726 heights from 259 boys; 3.759 from 271 girls, and a subgroup (AM) with >10 height measurements evenly distributed (15.324 in 989 boys; 14.381 in 919 girls), and of high data quality. The 1974 cohort, with similar subgrouping, were used for comparison. Methods: For construction of height curves the LMS method was applied with LMS parameters based directly on the data: the power in the Box-Cox transformation (L), the median (M), and the generalized coefficient of variation (S). The GAMLSS R-package with a special LMS program was used, giving L, M, S and optional kurtosis as functions of age.
Results: Height reference curves, with mean, ±1, ±2 SDS were obtained for 1990 of the ALL vs the AM material with similar results whereas the close puberty material showed the same mean but more narrow ±1, ±2 SDS during adolescence. When the different 1990 references were compared to 1974 references, the corresponding 1974 differences were found. The new references takes into account that the 1990 cohort had a more rapid infancy growth, increased prepubertal growth, especially in boys, increased pubertal gain, only in girls, and increased AH in both genders.
Conclusion: There were no or only small differences between the ALL and AM material for both boys and girls, except when using close puberty as inclusion criteria, where an expected reduced variation in total growth during adolescence was found. Thus, the entire 1990 ALL material will be used for developing new height references, taking the gender specific secular changes in height into account.
18 Sep 2014 - 20 Sep 2014