What Is a Chemical Pregnancy?
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Medically reviewed by Renita White, MD
A chemical pregnancy is a very early pregnancy loss. It’s usually defined as a pregnancy where a pregnancy test turns positive, but other signs of a pregnancy—such as a gestational sac—are never seen on an ultrasound. In other words, the pregnancy is only confirmed “chemically" with a positive pregnancy test.
A chemical pregnancy is sometimes referred to as a biochemical pregnancy, preclinical embryo loss, or trophoblast in regression. An estimated 8-33% of pregnancies are chemical pregnancies. Many people never even know they have them.
Chemical pregnancies usually occur quite early, with the person experiencing the loss around the same time as they would expect their period. However, chemical pregnancies are real pregnancies. Conception needs to occur for you to be pregnant, even if you're only pregnant briefly.
Related: Can You Get Pregnant Without Having Sex?
What Are the Signs of a Chemical Pregnancy?
Chemical pregnancies occur very early, so most people don’t experience many noticeable symptoms. You will likely receive a positive pregnancy test about 3-4 days before an expected menstrual period and then get a normal-seeming period on the day your period is due. Some people will experience a late period, but only by a few days.
In most cases, the most obvious “symptom” of a chemical pregnancy is a positive pregnancy test. Pregnancy tests detect the level of a hormone called human chorionic gonadotropin (hCG) in your blood or urine. These days, pregnancy tests are so sensitive that you can learn about a possible conception before you even miss your period. Many people experience chemical pregnancies without knowing it, simply because they never took a pregnancy test.
People who are very sensitive to changes within their body may notice symptoms like a period that's somewhat heavier than usual or a bit more menstrual cramping.
Related: How Soon After Unprotected Sex Should You Take a Pregnancy Test?
What Causes a Chemical Pregnancy?
Chromosomal abnormality is the most common cause of a chemical pregnancy. This accounts for about 50% of early pregnancy losses and chemical pregnancies.
Chromosomal abnormalities—for example, an incorrect number of chromosomes—cause an embryo to develop improperly. This makes the pregnancy nonviable, meaning there's no chance of the embryo surviving because it cannot develop normally. It usually happens very early in the pregnancy and can originate from either the sperm or the egg.
Pregnancy losses are usually considered “random events,” according to the American College of Obstetricians and Gynecologists (ACOG). They're not caused by factors like exercise, stress, working too much, medications, or having sex. Falling or blunt force to the abdomen doesn't cause chemical pregnancies. In short, you can't cause a chemical pregnancy.
Risk Factors
Chemical pregnancies and early pregnancy losses can happen to anyone, regardless of age or health status, but certain factors may increase your risk. These factors include advanced maternal age and a history of prior chemical pregnancy or early pregnancy loss.
After about the age of 40, the likelihood of experiencing a miscarriage (spontaneous abortion) increases significantly. At that age, about one in three pregnancies result in a miscarriage. This is usually because of chromosomal abnormalities, which increase with age.
Some chronic medical conditions and diseases may increase your risk of experiencing an early pregnancy loss. This includes:
Autoimmune disorders: When your immune system attacks healthy cells, tissues, or organs by mistake
Diabetes: When you have higher than normal levels of blood glucose (blood sugar)
Celiac disease: An autoimmune disorder that happens when your immune system reacts to eating gluten
Thyroid disease: Any condition that affects the functioning of your thyroid gland
Hyperprolactinemia: Abnormally high levels of the hormone prolactin
Infections: A syphilis, Zika, or cytomegalovirus (CMV) infection
Uterine abnormalities: Structural abnormalities like fibroids (tumors that are usually benign) or intrauterine adhesions (scar tissue)
Other risk factors include:
Becoming pregnant while you have an intrauterine device (IUD) in place
Smoking or using cocaine
Exposure to environmental pollutants like lead, arsenic, and organic solvents like benzene
Related: What Conditions During Pregnancy Are Hereditary?
How Is a Chemical Pregnancy Diagnosed?
Most chemical pregnancies are self-diagnosed after a positive pregnancy test. By the time you connect with your healthcare provider, it’s usually because you’ve gotten your period and realized in retrospect that you likely had a very early pregnancy.
Your healthcare provider may be able to detect and diagnose a chemical pregnancy. For example, they may do an early blood test to detect your pregnancy if you use assisted reproductive technology (ART) like in vitro fertilization (IVF). A chemical pregnancy is typically diagnosed with the following criteria:
Blood tests show a low hCG peak of less than 100 milli-international units per milliliter mIU/mL
Blood or urine tests show a rapid decrease in hCG concentration
A gestational sac (the fluid-filled sac that surrounds the embryo) is never seen on an ultrasound, either in the uterus (womb) or elsewhere in the body
Chemical Pregnancy Treatment
Chemical pregnancies usually don't require treatment. Most resolve on their own when hCG levels drop.
Your healthcare provider may want to monitor your levels of hCG to ensure they return to zero and to make sure that you aren’t experiencing an ectopic pregnancy. An ectopic pregnancy occurs when a fertilized egg implants outside the uterus, usually in a fallopian tube. It is a nonviable pregnancy that can be life-threatening.
Your provider may also want to meet with you to help you process the emotional effects of the chemical pregnancy and to address any questions or concerns you may have about a possible pregnancy in the future.
Emotional Effects of a Chemical Pregnancy
A chemical pregnancy can be an emotional rollercoaster. You may have positive or negative feelings when you see a positive pregnancy test. Those feelings may swing in a different direction when you learn the pregnancy isn't viable just a few days later. You may experience grief, relief, or a variety of other feelings. It's important to honor whatever you feel.
Many people who experience a chemical pregnancy question themselves and wonder if their pregnancy “counted.” They may feel guilty for feeling so upset about such a brief pregnancy and may compare their loss to the losses of those who’ve had later miscarriages or miscarriages that were more physically intense.
Try not to compare one type of grief to another. It's perfectly normal to feel upset about a chemical pregnancy. After all, a conception happened—even if briefly—and you have every right to grieve the loss. You also have the knowledge that, although this pregnancy didn’t “take,” your body was able to conceive. This can be affirming if you hope to conceive in the future.
Reach out to your healthcare provider if you need emotional support after a miscarriage. You may also find support through several organizations, including Share Pregnancy and Infant Loss Support.
Tips for Getting Pregnant After a Chemical Pregnancy
Chemical pregnancies are common. They don’t reflect anything about your fertility or your ability to get pregnant in the future. Most people who have chemical pregnancies can experience healthy pregnancies in the future. You might even get pregnant during your next cycle.
Your healthcare provider may want to run some tests if you experience repeat early pregnancies. Even if your provider diagnoses a cause (which is rare), most people can conceive eventually even after several early pregnancy losses.
Tracking your menstrual cycle can be a helpful starting point because ovulation is the most fertile time of your menstrual cycle.
Can a Chemical Pregnancy Be Prevented?
Miscarriages usually happen randomly. There is rarely anything that could have been done to prevent them. You may be able to pinpoint something that happened around the time of your miscarriage, but this is usually just a coincidence.
Factors like tobacco or cocaine use as well as poor nutrition may increase your risk of miscarriage. Refraining from these can decrease your risk.
A Quick Review
Chemical pregnancies are pregnancies that happen very early on. They're also known as biochemical pregnancies, preclinical embryo loss, or trophoblast in regression. With a chemical pregnancy, you typically experience a positive pregnancy test and then get your period soon after. An embryo is never seen on an ultrasound.
Chemical pregnancies are very common. Up to one-third of pregnancies are chemical pregnancies. A chemical pregnancy likely won’t affect your ability to get pregnant in the future. However, the experience can be incredibly upsetting and can cause significant distress.
Honor your emotional journey and know that it's valid, even if it doesn't seem as "real" as other pregnancy losses. Reach out for support by communicating with your healthcare provider, family and friends, and anyone else in your circle you feel comfortable sharing with. Support groups can also be valuable.
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