A blighted ovum, or anembryonic pregnancy, takes place when an egg that has been fertilized travels down the fallopian tube to the uterus where it is implanted in the uterine wall. Although it starts developing normally in some respects, by developing a sac, no embryo develops. Blighted ova account for approximately half of the miscarriages that occur in the first trimester of pregnancy. Because it typically happens so early in the pregnancy, the woman may not even know that she's pregnant and has a slightly late or heavier period than usual.

More recently, a blighted ovum may be referred to as an "early pregnancy failure." Unfortunately, there is nothing that can be done to save the pregnancy if a blighted ovum develops. It is typically caused by chromosomal abnormalities in the fertilized egg, which the body will not support. As a result, the egg will not continue to develop an embryo, resulting in an empty sac.

For women who experience a blighted ovum that lasts past when her normal period may start, she may have some early symptoms of pregnancy. As with any early pregnancy, she may experience tenderness in the breasts, nausea, fatigue, etc. Levels of hCG may even continue to rise for a while, and the placenta may grow as well. A woman may not even have any symptoms of a blighted ovum until an early ultrasound reveals that no embryo has developed in the sac.

Symptoms of a blighted ovum may include some light spotting, which may be dark red in color. You may also experience some cramping, due to falling hormone levels. If by 12 weeks, your doctor cannot find a heartbeat, he or she may conduct an ultrasound to examine the womb.

If you have a blighted ovum, you will have to choose between waiting to naturally miscarry, or to undergo a dilation and curettage (D&C). Waiting for a miscarriage can be emotionally difficult, but is the natural way to go. With a D&C, it is more medically invasive, will require recover time, but may ensure that all the tissue is expelled from your uterus.

Couples who have experienced a blighted ovum are advised to wait at least a couple of menstrual cycles before attempting to get pregnant again. Most doctors will tell you that one blighted ovum does not predispose you for more or for any future complications during pregnancy.