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

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.