title: Insulin-like growth factor-I in cord blood is predictive of catch-up growth in monozygotic twins with discordant growth.
abstract: OBJECTIVE
  The aim was to investigate the growth of monozygotic twins with discordant birth weights and the predictive value of birth-weight, birth-length, and cord-blood concentration of growth factors on their catch-up growth up to the age of 4 yr.
  
  
  METHODS
  Twenty-five monozygotic twin-pairs [14 with an intertwin birth-weight sd score (SDS) difference>1] were studied at birth and at 4 yr of age. In all pairs, several parameters including IGF-I were analyzed in cord blood, and in 20 pairs parameters were analyzed again at 4 yr of age. Intertwin differences (Δ) in birth weight, birth length, and growth at 3, 6, 12, 24, and 48 months were correlated with Δ of the parameters analyzed.
  
  
  RESULTS
  We found a reduction of Δ height SDS from birth to 4 yr, with the main catch-up occurring during the first year, but only a slight, statistically insignificant reduction of Δ body mass index SDS during the observation period. Correlation coefficients were used to identify factors predicting postnatal catch-up growth. Both birth-weight difference (r=0.653; P=0.001) and Δ IGF-I in cord blood (r=0.613; P=0.007) were of similar predictive value. Variance analysis showed no significant difference in individual impact between these two parameters, although both correlated strongly with actual height.
  
  
  CONCLUSIONS
  We observed a gradual convergence in height but not body mass index up to the age of 4 yr between genetically identical twins with discordant birth weights. Both birth-weight and cord-blood IGF-I are predictive of subsequent catch-up growth.
authors.affiliation: Department of Pediatrics, University of Bonn, Adenauerallee 119, 53113 Bonn, Germany. bettina-gohlke@t-online.de
authors.forename: Bettina C
authors.initials: BC
authors.lastname: Gohlke
authors.forename: Felix
authors.initials: F
authors.lastname: Schreiner
authors.forename: Rolf
authors.initials: R
authors.lastname: Fimmers
authors.forename: Peter
authors.initials: P
authors.lastname: Bartmann
authors.forename: Joachim
authors.initials: J
authors.lastname: Woelfle
mesh_terms: D001724:Birth Weight; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002675:Child, Preschool; D005260:Female; D005312:Fetal Blood / Q000378:metabolism*; D006128:Growth / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D010920:Placenta / Q000502:physiology; D011237:Predictive Value of Tests; D011247:Pregnancy; D014430:Twins, Monozygotic
chemical_list: D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II