A chemical pregnancy refers to a very early miscarriage that occurs after conception when the fertilized ovum fails to implant in the uterus. Chemical pregnancies are often referred to as a false positive and usually happen within the first five weeks of pregnancy. They often go unnoticed and are thought to be fairly common.

After conception, a pregnancy confirmed by using normal home pregnancy tests will detect levels of hCG, or human growth hormone. A more sophisticated blood test, usually done in a clinical setting, will also detect hCG levels and will confirm the pregnancy. Both are accurate diagnoses in that conception did occur, however in the instance of a chemical pregnancy, the fertilized ovum fails to implant into the walls of the uterus thus ending in miscarriage. This early miscarriage occurs before an ultrasound could have shown images of a gestational sac or pick up a heartbeat. If the pregnancy were to develop to the point that an ultrasound could pick up images confirming the implantation, it then becomes a clinical pregnancy.

Signs and symptoms of chemical pregnancy include vaginal bleeding shortly after having a positive pregnancy test, and blood tests revealing hCG hormones decreasing rather than increasing. Unusually heavy periods, late periods, or periods accompanied by cramps and mild clotting have been known to accompany chemical pregnancies.

Most doctors believe a chemical pregnancy occurs for the same reasons as most other miscarriages or spontaneous abortions — chromosomal abnormalities in the developing fetus, inadequate uterine lining, uterine abnormalities, low hormone levels and infections. It is unclear exactly what causes chemical pregnancies, as it is nearly impossible to obtain any DNA samples for chromosomal testing.

Some researchers have theorized that as many as 70% of conceptions end in early miscarriage, however it is highly unknown how common a chemical pregnancy is. In some cases, women who are not trying to conceive and not closely monitoring their menstrual cycles may have chemical pregnancies and never know it.

Chemical pregnancies usually have little effect on women’s bodies and often go unnoticed. These early miscarriages are mistaken for a late or irregular period, and in some cases, are accompanied by more cramps. Adequate medical attention should be obtained after an early miscarriage, so as to ensure a complete expulsion of fetal tissue.

Unfortunately, there is no way to prevent a chemical pregnancy.