11.   That is also about the time a fertilized human egg implants on the uterine wall, West said.

12.   The agency considers morning-after pills a form of contraception since they block the fertilized egg from implanting into the uterine wall.

13.   The prevailing thinking was that scar tissue from the surgical incision rendered the uterine wall too weak to withstand the strain of powerful contractions during labor.

14.   This time the cause was uterine fibroids, benign tumors on the uterine wall.

15.   Fibroids are bundles of muscle fiber and connective tissue that typically grow inside the uterus or uterine wall.

16.   It impedes a possibly fertilized egg from imbedding in the uterus by altering the uterine wall.