Also known as an 'anembryonic pregnancy' or 'anembryonic gestation', a blighted ovum happens when there is an absence of a visible embryo developing in the uterus. Often discovered early in pregnancy, a blighted ovum occurs when cells form a pregnancy sac but the embryo itself fails to grow. When a blighted ovum is present, pregnancy hormones will begin to drop thus resulting in a miscarriage. Fifty percent of first trimester miscarriages are due to a blighted ovum. No fault of the pregnant woman, a blighted ovum is the body's natural way of not progressing with a pregnancy that will result in an unhealthy baby. The woman's body recognizes abnormal chromosomes, in the fetus, which may be due to early bad cell division, poor quality sperm or an unhealthy egg. Once it has been discovered that a blighted ovum is present the pregnant woman may choose to miscarry naturally or have a procedure, known as a D&C, performed.