The aim of this study was to determine if loss of pregnancy is associa
ted with a decrease in plasma levels of gravidin, a phospholipase inhi
bitor thought to maintain pregnancy. Blood was taken from 28 women in
the first trimester of pregnancy who had requested an abortion. The pr
ogesterone receptor antagonist, RU-486 was given on Day 0 for terminat
ion of pregnancy. Plasma gravidin levels were measured on day 0 and on
day 2 lust before the patients were given misoprostol, a prostaglandi
n E1 analogue (600 mu g). In a small group of patients, plasma measure
ments were continued up to 42 days. By day 2, plasma gravidin levels h
ad fallen significantly (100% to 94%, p = 0.010 in a paired t-test). F
ollowing treatment with prostaglandins and pregnancy loss, plasma grav
idin levels continued to fall until day 14 when the non pregnant level
was reached at 80% of the pregnant level. We conclude that a decrease
in plasma gravidin levels is associated with loss of pregnancy. This
may occur because progesterone action is blocked.