[Cloning and associated physiopathology of gestation]

Normal fertile offspring can be produced with nuclear transfer (NT) of somatic cells. This technique is associated with important gestational losses in early pregnancy during the first two to three months and in the late fetal and perinatal periods in cows. In cows and sheep, recent studies suggest that early losses may be associated with placental vascularisation deficiencies. In late gestation and at term, a syndrome, commonly called the large offspring syndrome (LOS), causes important perinatal deaths. This syndrome is associated with increased fetal and placental growth, disturbed placental function and fetal abnormalities. Moreover, prolonged gestations are common. Live offspring occasionally exhibit a respiratory distress syndrome and several types of abnormalities that may hinder their survival. This paper reviews the current knowledge about these pathologies and their incidence in somatic and embryonic cloning.