The IGF system and longitudinal growth in preterm infants in relation to gestational age, birth weight and gender

Growth Horm IGF Res. 2020 Apr:51:46-57. doi: 10.1016/j.ghir.2020.02.002. Epub 2020 Feb 19.

Abstract

Objective: Growth factors in the blood of very preterm infants may reflect growth and contribute to the understanding of early development. We investigated postnatal levels of insulin-like growth factors (IGFs) in infants born very preterm and related them to early growth development.

Design: Blood samples were analyzed weekly for IGF-I, IGF-II, IGF binding protein (BP)-1, IGFBP-3, and acid-label subunit (ALS).

Methods: 73 children born very preterm (gestational age (GA) <32 weeks) were divided according to their gender-specific birth weight standard deviation score (SDS) into either appropriate for GA (AGA) or small for GA (SGA). Fifty-two (71%) and forty-three (59%) infants completed follow-up with anthropometry at approximately 3 years and at 5 years of age respectively. Thirty-six subjects (49%) had blood sampling for IGF-I and IGFBP-3 measurements up to 3 years of age.

Results: IGF-I, IGFBP-3, and ALS levels increased in all groups from week 31 to week 36, with generally lower levels in the SGAs, with a concomitant lower growth velocity. Postnatal ALS was strongly associated with IGF-I and IGFBP-3 in boys, girls and AGA infants. IGF-II was higher in earlier born preterms (GA < 27 weeks) at postmenstrual ages 27.5-29.9 weeks compared with SGAs and late GA (GA ≥ 27 weeks) preterms (p < .0001). IGF-II, in contrast to IGF-I, did not differ between SGAs and AGAs at weeks 31-36. Mean IGFBP-1 was highest in the SGAs compared to AGAs at mean week 28,5 and 31 (p = .001) and IGFBP-1 levels were elevated in relation to IGF-I in the SGAs at that period. At follow-up, the increase in IGF-I between week 31 and 33.5 was a significant positive determinant of height SDS at 3 and 5 years of age in forward multiple regression analysis, independent of target height.

Conclusion: This is the first study to investigate postnatal ALS levels in preterm infants. In very preterm infants, IGF-II is less affected by size at birth during early postnatal weeks compared with IGF-I. Early elevated IGFBP-1 might protect the SGA infants from an intense metabolic rate. Our results indicate that anabolic and metabolic processes during weeks 31-36 predicts later height.

Keywords: ALS; IGF-I; IGF-II; IGFBP-I; Preterm children.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Birth Weight*
  • Body Height*
  • Carrier Proteins / metabolism*
  • Child, Preschool
  • Female
  • Gestational Age*
  • Glycoproteins / metabolism*
  • Humans
  • Infant
  • Infant, Extremely Low Birth Weight
  • Infant, Extremely Premature
  • Infant, Low Birth Weight
  • Infant, Newborn
  • Infant, Premature
  • Infant, Small for Gestational Age
  • Infant, Very Low Birth Weight
  • Insulin-Like Growth Factor Binding Protein 1 / metabolism*
  • Insulin-Like Growth Factor Binding Protein 3 / metabolism*
  • Insulin-Like Growth Factor I / metabolism*
  • Insulin-Like Growth Factor II / metabolism*
  • Longitudinal Studies
  • Male
  • Sex Factors

Substances

  • Carrier Proteins
  • Glycoproteins
  • IGF1 protein, human
  • IGF2 protein, human
  • IGFBP1 protein, human
  • IGFBP3 protein, human
  • Insulin-Like Growth Factor Binding Protein 1
  • Insulin-Like Growth Factor Binding Protein 3
  • insulin-like growth factor binding protein, acid labile subunit
  • Insulin-Like Growth Factor I
  • Insulin-Like Growth Factor II