A chemical pregnancy is a very early miscarriage that occurs when an egg is fertilized but doesn’t fully implant in the uterus. The pregnancy is lost before the fifth week.Chemical pregnancies (also known as biochemical pregnancies) are very common.
What’s more, research has found that up to one in four pregnancies is lost even before a woman misses her period or has symptoms of pregnancy — these are chemical pregnancies.
The term “chemical pregnancy” refers to a positive result on a blood or urine test that gauges the presence of a hormone, human chorionic gonadotropin (hCG), to detect a pregnancy. But many women who have a chemical pregnancy don’t even realize they’re pregnant because the loss is so early; they may not have taken a pregnancy test,had any pregnancy symptoms, or even missed a period. They may simply have a late period that’s a bit heavier than usual.

Causes and Risk Factors of Chemical Pregnancy

Most miscarriages, including chemical pregnancies, are caused by chromosomal abnormalities that prevent the fetus from developing normally.In an assisted pregnancy that uses frozen embryos, damage that occurs to the embryo during the freezing process may result in a chemical pregnancy; as many as 25 percent of pregnancies resulting from in vitro fertilization (IVF) result in a chemical pregnancy.

Other causes can include:

  • An insufficient (too thin) uterine lining
  • A problem with DNA in the sperm
  • Low hormone levels
  • Infections
  • Pregnancy with an IUD in place
Meanwhile, certain conditions can put a woman at increased risk for a chemical pregnancy. These include being 35 or older, having an untreated clotting disorder or thyroid condition, or having another poorly controlled chronic medical condition such as diabetes.

Duration of Chemical Pregnancy

By definition a chemical pregnancy occurs before the fifth week of pregnancy; it’s a very early miscarriage, in other words. The bleeding and cramping may last for a few days.

Complications of Chemical Pregnancy

There aren’t usually any physical complications of chemical pregnancy, aside from cramping and sometimes heavier-than-usual bleeding. In rare instances, women may experience very heavy bleeding or hemorrhaging after a chemical pregnancy, which can lead to anemia; this requires medical attention.

RELATED: Early Pregnancy Loss May Trigger Post-Traumatic Stress Symptoms

But keep in mind that any kind of miscarriage can be upsetting, especially if you were trying to conceive or were excited about a positive pregnancy test or you went through fertility treatment. As a result, you may experience stress-related symptoms or mood changes. Some women find that early pregnancy loss can even trigger post-traumatic stress symptoms, such as intrusive or unwanted thoughts about the pregnancy loss, nightmares or flashbacks, hyperarousal, and avoidance of anything that reminds women of their loss.
Be sure to give your body and your mind ample time to recover from the loss.Whatever your feelings are, accept them and allow yourself time to fully process them, perhaps with support from friends, family members, or support groups.

Research and Statistics: How Many People Have a Chemical Pregnancy?

Chemical pregnancies are extremely common — as many as one-third of all pregnancies may be chemical pregnancies, and up to 22 percent of IVF pregnancies may be chemical pregnancies.

But in many cases, women don’t even know they were pregnant because the pregnancy loss occurs so early.   

Resources We Love

To learn more about chemical pregnancies, check out the following websites:

The American College of Obstetricians and Gynecologists (ACOG) 

ACOG is a go-to source for research-supported information about women’s reproductive health issues, including conception, pregnancy and pregnancy loss, and best practices for each of these issues.

Miscarriage Association

A valuable source of information about various types of miscarriages and how they affect women physically and emotionally, this U.K.-based organization also provides news and research updates and various support services.

Editorial Sources and Fact-Checking

  • What Is a Chemical Pregnancy? What to Expect. May 22, 2020.
  • Chemical Pregnancy vs. Miscarriage. Medicinenet. December 20, 2019.
  • Annan JJ, Gudi A, Bhide P, et al. Biochemical Pregnancy During Assisted Conception: A Little Bit Pregnant. Journal Clinical Medicine Research. August 2013.
  • Prager S, Micks E, Dalton V. Pregnancy Loss (Miscarriage): Risk Factors, Etiology, Clinical Manifestations, and Diagnostic Evaluation. UpToDate. June 29, 2020.
  • Chemical Pregnancy. Miscarriage Association.
  • Farren J, Jalmbrant M, Falconieri N, et al. Posttraumatic Stress, Anxiety and Depression Following Miscarriage and Ectopic Pregnancy: A Multicenter, Prospective, Cohort Study. American Journal of Obstetrics & Gynecology. April 2020.
  • Everything You Need to Know About Chemical Pregnancies. Medium. September 23, 2020.


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