Abstract
Plasma diamine oxidase [DO] levels were assayed in 66 patients who presented with pregnancy complicated by threatened abortion. Levels within the normal range were associated with continuing pregnancies, whereas levels below the normal range were associated with subsequent abortion. Among those patients in whom gestation was greater than 8 wk, 66.6% of DO levels correctly predicted the pregnancy outcome. Assay of the DO levels at 8 wk of gestation or less gave little useful information.