Enteral IGF-I enhances fetal growth and gastrointestinal development in oesophageal ligated fetal sheep

Infants with upper gut atresia often have impaired intrauterine growth and gut function. IGF-I is important in fetal growth and is contained in amniotic fluid. We therefore wanted to test the hypothesis that IGF-I infused into fetal gut would reverse the effects of an upper gut obstruction on gut structure and growth in fetal sheep. At 90 days gestation fetuses (n=6 per group) underwent oesophageal ligation, followed by continuous infusion of IGF-I (1-8 microgram/day) or saline into the gut beyond the ligation until 137 days. Controls underwent sham ligation only. Oesophageal ligation tended to reduce fetal body and organ weights. IGF-I treatment prevented this reduction and increased body length and spleen weight above those of controls. The decrease in bowel wall thickness induced by oesophageal ligation was also prevented by IGF-I treatment. Amniotic fluid IGF-I concentrations did not change over gestation and were higher in the IGF-I treated group. No change in fetal plasma IGF-I concentrations were detectable. We conclude that enterally administered IGF-I may enhance fetal growth and gut development in utero and that IGF-I in amniotic fluid may play a physiological role in gut development in the fetus.