Molar pregnancy is also called hydatidiform mole. You need to know a tiny bit of embryology to understand this. When the fertilized egg starts to divide, it makes a large, almost hollow ball. This ball implants in the uterus by eating away some of the endometrium with proteolytic enzymes (it digests some proteins and buries itself in the uterine lining). The outside cells of the ball become the membranes, the chorion (part of which becomes the placenta) and amnion. A tiny speck of cells inside becomes the baby, and this speck grows away from the membranes into the fluid filled center of the ball, leaving a stalk connecting them, which becomes the umbillical cord. Thus, the baby makes it's own placenta, membranes, and cord. A molar pregnancy occurs when the baby part of the embryo dies ("blighted ovum") and the chorion undergoes cellular changes (hyperplasia and anaplasia) and keeps growing. It is the precursor to choriocarcinoma, cancer of the chorion, so it is very important to treat. Please give your friend our condolences on the loss of her baby. -- Catherine Watson Genna, IBCLC NYC [log in to unmask]