Gene expression patterns of insulin-like growth factor 1, 2 (IGF-1, IGF-2) and insulin-like growth factor binding protein 3 (IGFBP-3) in human placenta from preterm deliveries: influence of additional factors

Abstract

Objective: To compare patterns of human placental gene expression of IGF from pregnancies that ended with preterm delivery vs. full term pregnancies as controls.

Study design: Real-time PCR was used to assess gene expression of IGF in human placental samples from 104 preterm and 140 full term pregnancies.

Results: In the preterm delivery group, the proportion of smokers was significantly higher than in the control group. A history of preterm delivery was more common in the preterm delivery group compared to the control group. In the preterm delivery group, placental samples showed an underexpression of the IGF-1 gene compared to controls. In cases of male fetal gender an overexpression of both the IGF-2 and the IGFBP-3 genes was observed.

Conclusion: Among environmental factors influencing preterm delivery, smoking was the most significant in our study. In the majority of cases, preterm delivery was induced by intrauterine infection leading to a decreased activity of the IGF system. This mechanism may also play a role in the development of neurological sequelae and in decreased tolerance to fetal distress. The overexpression of the IGF-2 gene observed in the placenta with male fetal gender can be explained by its physiological role in the development of the male phenotype.