ESPE Abstracts

Background, objective and hypotheses: By using QEPS, a new mathematic growth model, different components of growth can be analyzed, comparing secular trends of prepubertal and pubertal growth in Swedish birth cohorts born 1974 and 1990.

Materials and methods: Two birth cohorts followed to adult height (AH) born around 1974 (1691 boys; 1666 girls) and 1990 (1647 boys; 1501 girls) being healthy, Nordic and born term. A subpopulation of 1974 (1177 boys; 1168 girls) and 1990 (989 boys; 919 girls) with >10 height measurements evenly distributed during growth phases, and high data quality was used for comparison. The different components of the QEPS-model: (Q)uadratic, (E)xponential, (P)ubertal, and (S)top function were estimated with corresponding maximum values at AH and tempo adjusting ‘time scale ratios’ of E and P. Multivariate regression analyses were used for explaining the variation of AH.

Results: Both boys and girls born 1990 compared to those born 1974 had at birth an increased length_SDS and weight_SDS and during infancy a more rapid growth (shorter E_timescale). Boys -1990 had increased prepubertal growth (P<0.0001 for Q_max, Q_heightscale), their pubertal part of growth was not significantly changed. Their AH_cm increased 1.3 from 180.4 to 181.7; the variation in AH was explained to 44% by mid parental height (MPH) and birth characteristics, to 72% by adding Q_max, to 75% by pubertal onset age and to 99% by P_max. Girls -1990 had prepubertal growth increased (P<0.05 for Q_max, Q_heightscale). Their pubertal gain was markedly increased (P<0.001 for P_max; P_heightscale), and duration decreased whereas mean menarche age remained 12.8 years. AH_cm increased 0.7 from 167.6 to 168.3. AH could be explained to 52% by MPH and birth characteristics, to 71% by adding Q_max, to 75% by pubertal onset, and to 99% by P_max.

Conclusion: In cohorts born 16-years apart; a secular trend with increased AH_cm was found, 1.3 in boys, due to more prepubertal growth, 0.7 in girls, due to more pubertal growth, indicating gender specific underlying regulations.