What is a chemical pregnancy?

A chemical pregnancy is a very early pregnancy loss. It happens before the fifth week of pregnancy, usually about a week after your menstrual period is due. Chemical pregnancies are very common, and they often happen before a woman even realizes that she's pregnant. But some women who have been watching closely for signs of pregnancy may wonder if their late period is actually a miscarriage.

When a chemical pregnancy happens, there is a fertilized egg, but it hasn't completely implanted. It "sticks" just enough for your body to produce the pregnancy hormone hCG, though. That's why you might have a faintly positive pregnancy test early on. Once the implantation is unsuccessful and the embryo stops developing, however, hCG levels fall. So, if you took a pregnancy test a week or two later, you would get a negative result.

A chemical pregnancy is sometimes called a biochemical pregnancy. Some people use the term chemical miscarriage, and many women think of a chemical pregnancy as a miscarriage. Medically, however, chemical pregnancy isn't considered a miscarriage because it doesn't meet the definition of a clinical pregnancy.

A clinical pregnancy means that the gestational sac can be seen on an ultrasound or that the fetal heartbeat can be heard. In a clinical pregnancy, a blood test would show rising hCG levels, while in a chemical pregnancy the hCG levels may not be detectable, or they may be falling.

Between 8 and 33 percent of all pregnancies and 18 to 22 percent of all in vitro fertilization (IVF) pregnancies are chemical pregnancies.

Signs of a chemical pregnancy

There are usually no signs of a chemical pregnancy, but you might suspect one based on:

  • A late period, which usually looks and feels like a normal period except for timing
  • A faint positive on an early pregnancy test
  • Menstrual-like cramping, though this doesn't always happen

It's too early to have pregnancy symptoms such as fatigue or nausea.

Causes of a chemical pregnancy

The most common cause of a chemical pregnancy is a problem with the pregnancy, such as a chromosomal abnormality. These abnormalities (which happen when the cells don't divide properly) usually occur randomly, and they don't mean you'll have trouble with a future pregnancy. Other possible causes include:

  • Abnormal hormone levels
  • Implantation outside the uterus (ectopic pregnancy)
  • Uterine abnormalities

Risk factors for chemical pregnancies

Chemical pregnancies aren't predictable, and there usually isn't anything you can do to prevent one. But the following might increase the risk of a chemical pregnancy:

Treatment for a chemical pregnancy

Usually no treatment is necessary for a chemical pregnancy. Your body will probably just pick up your menstrual cycle as before.

Can I get pregnant after a chemical pregnancy?

You absolutely can get pregnant after a chemical pregnancy. In fact, it's a good sign that you're able to get pregnant. Chances are that your next pregnancy will proceed normally.

It's unlikely that you'll have a repeated chemical pregnancy, but if you think you've had more than one, be sure to talk with your caregiver about possible causes.

How can I tell the difference between implantation bleeding and a chemical pregnancy?

The difference between implantation bleeding and a chemical pregnancy comes down to timing and amount.

When the embryo attaches to the uterus, it's normal to have something called implantation bleeding. This light spotting usually happens around one to two weeks after conception, and it's a sign that you're pregnant.

A chemical pregnancy, on the other hand, would cause a normal menstrual period, most often around four to five weeks gestation.

Coping with a chemical pregnancy

Coping with a chemical pregnancy can be very painful. While some women never know they were pregnant, others may be very disappointed, or even devastated, by the loss.

If you're struggling with this, know that your pregnancy loss is very real, and grief is perfectly normal. Reach out to others who can support you and help you cope. You might want to talk to others in BabyCenter's grief and loss community groups.

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