Implantation Bleeding or Early Miscarriage?

Signs that Early Pregnancy Bleeding May Be Implantation vs. Miscarriage

Implantation bleeding is vaginal bleeding that occurs in some women during the first few weeks of pregnancy. Since so many women have unexplained spotting or light bleeding early in viable pregnancies, the theory is that harmless light bleeding can occur as the fertilized egg implants and the uterus begins to adjust to the pregnancy.

There's not a lot of research about the exact reasons why some women have this bleeding and others do not, but implantation bleeding is no cause for concern and does not affect the viability of the pregnancy.

Similarly, not having implantation bleeding should not be considered a cause for worry.

Timing of Implantation Bleeding

The time when implantation bleeding occurs should usually be within the first two weeks after fertilization, up to the time that the woman expects her menstrual period. Note that implantation bleeding is an imprecise term; although the fertilized egg implants in the uterus about 8 to 10 days after ovulation, light bleeding can occur at other times in early pregnancy and a doctor may still refer to the bleeding as "implantation bleeding."

Due to the timing, implantation bleeding could also be mistaken for an extremely light menstrual period in some women. If you have unusually light bleeding around the time of your menstrual period and that does not turn into a heavier, normal flow, consider taking a pregnancy test.

Implantation Bleeding or Early Miscarriage?

Distinguishing implantation bleeding from early miscarriage bleeding can be confusing as well.

In general, bleeding associated with an impending miscarriage or chemical pregnancy may begin as spotting but then turn into a heavier flow with visible clots and a dark red color (similar to a menstrual period). In contrast, implantation bleeding may appear as a brown or lighter colored discharge without clots with a lighter flow that lasts only a few hours to a few days.

Neither rule is universally true, however, and the best way to determine the cause of early pregnancy bleeding is to visit your doctor for hCG blood tests or an early pregnancy ultrasound.


American Pregnancy Association, "Bleeding During Pregnancy." Aug 2007. Accessed 20 Jun 2008.

Mayo Clinic, "Bleeding During Pregnancy: What It Happens, What to Do." Mayo Clinic Health Information May 2007. Accessed 20 Jun 2008 at

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