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.

中文翻译：

---

IGF系统和早产儿的纵向生长与胎龄，出生体重和性别有关。

目的

早产儿血液中的生长因子可能反映生长并有助于早期发育的了解。我们调查了早产儿的胰岛素样生长因子（IGFs）的出生后水平，并将其与早期生长发育相关。

设计

每周对血样进行IGF-I，IGF-II，IGF结合蛋白（BP）-1，IGFBP-3和酸标记亚基（ALS）分析。

方法

将73例早产儿（胎龄（GA）<32周）根据其性别特定的出生体重标准差评分（SDS）分为适合GA（AGA）或适合GA（SGA）的小孩子。52名（71％）和43名（59％）婴儿分别在大约3岁和5岁时完成了人体测量学的随访。36位受试者（49％）进行了3岁以下的IGF-I和IGFBP-3测量的血液采样。

结果

从第31周到第36周，所有组的IGF-1，IGFBP-3和ALS水平均升高，而SGA中的水平通常较低，同时生长速度也较低。在男孩，女孩和AGA婴儿中，产后ALS与IGF-1和IGFBP-3密切相关。与SGA和GA晚期（GA≥27周）早产相比，月经后27.5–29.9周的早产早产（GA <27周）中的IGF-II更高（p  <.0001）。与IGF-I相比，IGF-II在第31-36周的SGA和AGA之间没有差异。在平均周28,5和31时，SGA中的平均IGFBP-1高于AGA（p = 0.001），并且在那个时期SGA中的IGFBP-1水平相对于IGF-I升高。在随访中，IGF-I在第31周至33.5周之间的增加是前向多元回归分析中3岁和5岁时身高SDS的重要正向决定因素，与目标身高无关。

结论

这是第一项研究早产儿产后ALS水平的研究。与IGF-I相比，在早产儿中，IGF-II在出生后早期几周出生时受大小的影响较小。早期升高的IGFBP-1可能会保护SGA婴儿免于强烈的新陈代谢。我们的结果表明，在31至36周内的合成代谢和代谢过程可预测以后的身高。