Histocompatibility between the mother and father and in turn the foetus. It is more common for the foetus to be expelled but for the placenta to be retained due to firmer attachment to the uterine wall. Vaginal bleeding slight or mild, bright red in colour originating from the choriodecidual interface. Pain is absent or slight. Cervix is closed.
Pregnancy test is positive.
Ultrasonography shows a living foetus. If the blood loss is less than a normal menstrual flow and is not accompanied by pain of uterine contraction there is a reasonable chance for continuing pregnancy. Rest in bed until one week after stoppage of bleeding. No intercourse as it may disturb pregnancy by the mechanical effect and the effect of semen prostaglandins on the uterus. However, low plasma progesterone level is an indication of pregnancy failure.