A. Vascular accident.
B. Nutritional adequacy.
C. Endocrine insufficiency.
D. Immune response of mother.
The condition shown in the picture above represents ectopic pregnancy.
Lack of a submucosal layer within the fallopian tube provides easy access for the fertilized ovum to burrow through the epithelium and allow implantation within the muscular wall. As the rapidly proliferating trophoblasts erode the subjacent muscularis layer, maternal blood pours into the spaces within the trophoblastic or the adjacent tissue.
The fallopian tube cannot sustain the growing pregnancy. This causes rupture and bleeding which expels the implantation out of the tubal end as tubal abortion.