['The aim of this study was the measurement of maternal serum levels of M-CSF throughout pregnancy, in a low risk obstetrical population, to examine the relationship of M-CSF and pregnancy outcome.', 'Maternal serum was obtained at various stages of pregnancy and post partum, M-CSF levels were measured by ELISA, pertinent clinical data tabulated, and pregnancy outcome was determined.', 'In 564 pregnancies studied, 22% of 260 nulliparous pregnancies and 10% of 304 multiparous pregnancies were hypertensive. Preeclampsia occurred in 1.5% of nulliparous and in 1% of the multiparous women. In apparently normal pregnancies with good outcome, M-CSF levels rose throughout pregnancy. No cases of preeclampsia occurred if maternal serum M-CSF levels increased more than 100% throughout pregnancy.'] Are maternal serum levels of macrophage colony-stimulating factor associated with adverse pregnancy outcome?