A malnourished fetus has a higher concentration of pulmonary surfactant in the amniotic fluid than its well-nourished contemporary. The clinical value of this observation is discussed. Malnourished fetuses have higher "fat cell" counts in their amniotic fluid than well-nourished contemporaries. Well-nourished fetuses, at the same gestational age have high fat cell counts when the surfactant concentration is high, and low fat cell counts when the surfactant concentration is low. The relationship between surfactant concentration and the fat cell count is discussed.