What to know about a chemical pregnancy and how it affects your fertility, according to OBGYNs

• A chemical pregnancy is an early type of miscarriage that takes place shortly after conception.
• It happens when an egg and a sperm combine, but the combination doesn't develop into an embryo.
• Doctors say that a chemical pregnancy is a good sign that you can get pregnant.

Conception doesn't always lead to a baby. Sometimes pregnancy ends quickly on its own.

A very early type of miscarriage known as a chemical pregnancy takes place shortly after conception, and you may not even notice it unless you take a sensitive pregnancy test.

A chemical pregnancy does not produce an embryo

"What happens is a woman comes in and she has a positive pregnancy test, and you look on an ultrasound and you don't see an embryo," says Michael Cackovic, MD, who practices maternal-fetal medicine at The Ohio State University Wexner Medical Center.

A chemical pregnancy happens when one of your eggs and a sperm combine, but the combination doesn't develop into an embryo. Technically, you've conceived, which is why a pregnancy test might give you a positive result.

But if no sign of an embryo appears on a second ultrasound at a later date, then you probably experienced a chemical pregnancy, Cackovic says.

Symptoms of a chemical pregnancy

It's a condition that can easily go unnoticed. "Sometimes women don't even know they are pregnant," Cackovic says, and their period is "just late."

Since a chemical pregnancy happens early on, chances are you may have experienced some of the typical symptoms of early pregnancy, including morning sickness, breast tenderness, and fatigue.

Yet if you've had a chemical pregnancy you'll probably see those symptoms disappear and you might experience bleeding as well, says Maura Quinlan, MD, an associate professor of Obstetrics and Gynecology at Northwestern University Feinberg School of Medicine.

Chemical pregnancies are common

It's unclear how frequently chemical pregnancies occur, but doctors say they're common.

"Back in the day, pregnancy tests were only done when someone missed two periods," Quinlan says. "No one knew they were having miscarriages."

But because of the highly sensitive tests in use today, people are now more aware of early miscarriages, she adds.

Causes of a chemical pregnancy

Chemical pregnancies can occur for a number of reasons. The most common has to do with problems with the chromosomes in your egg or your partner's sperm.

Normally during conception, you pass on 23 chromosomes and your partner contributes 23 for a total of 46 chromosomes. But sometimes that number is too high or too low, which can lead to a chemical pregnancy.

Half of all miscarriages that occur within the first trimester - or 13 weeks of pregnancy - happen because an egg or sperm carries an abnormal number of chromosomes, according to the American College of Obstetricians and Gynecologists.

Yet you have no control over this abnormality. There's no activity - exercise, sex, fasting - that can cause a chemical pregnancy.

Cackovic says that he tells his patients, "That glass of wine you had before you knew you were pregnant did not do this. It was a predetermined situation."

And you shouldn't get too discouraged because "it is a good sign that a pregnancy started," Quinlan says. If you're having trouble getting pregnant in the first place - say, if the man has a low sperm count - then you're unlikely to have a chemical pregnancy.

Therefore, a chemical pregnancy is a sign that you can get pregnant and should try again if you so choose.

Insider's takeaway

A chemical pregnancy is a very early miscarriage that happens when the egg and sperm combine without resulting in an embryo. You will likely only know that you've had a chemical pregnancy if you take a very sensitive pregnancy test.

If you're trying to get pregnant, a chemical pregnancy could be a good sign that conceiving is possible - you'll just have to try again.