Elevation of macrophage colony-stimulating factor in amniotic fluid at late stage of normal pregnancy.

Problem: Macrophage colony-stimulating factor (M-CSF) promotes placental growth and maintenance, and regulates trophoblast invasion into the placental bed. We evaluated whether the amniotic fluid M-CSF levels at the late stage of normal pregnancy is altered compared with those at the middle stage.

Method Of Study: This study enrolled 52 subjects experiencing normotensive pregnancies with single fetuses, of whom 26 were women at the late stage (term gravidas) and 26 were women at the middle stage (controls). The average gestational age at entry was 38 weeks of gestation and 17 weeks, respectively. Amniotic fluid was collected from these subjects. Amniotic fluid M-CSF levels were determined by the enzyme-linked immunosorbent assay method then compared between term gravidas and controls.

Results: Amniotic fluid M-CSF concentrations were 4815 pg/mL (median) in term gravidas and 3795 pg/mL in controls; the concentrations were significantly higher in term gravidas than in controls.

Conclusions: We demonstrated a significant increase in amniotic fluid M-CSF levels in term gravidas. These results suggest that elevated levels of M-CSF in amniotic fluid have an important immunological function in the maintenance of pregnancy and fetal growth.