• An ectopic pregnancy is a type of miscarriage that happens when a fertilized egg attaches outside of the uterus. If left untreated, it can cause organ damage or death.
• Symptoms of an ectopic pregnancy include pelvic pain, lower back pain, abnormal vaginal bleeding, and dizziness.
• If you smoke or drink during pregnancy, this can increase your risk of an ectopic pregnancy. Other risk factors include getting pregnant with an IUD, being over 35 when you become pregnant, or having a history of ectopic pregnancy.
• In an ectopic pregnancy, the egg can not move into the uterus for a healthy pregnancy. To remove it, you'll either receive medication or surgery, depending on the situation.
• This article was reviewed by Karen Duncan, MD, who is an assistant professor with the Department of Obstetrics and Gynecology at NYU Langone.

An estimated 10 to 15 percent of pregnancies end in miscarriage. And of those, one to two percent is a type of miscarriage called an ectopic pregnancy.

An ectopic pregnancy happens soon after fertilization

An ectopic pregnancy happens when a fertilized egg implants, or attaches, outside of the uterus instead of inside. It usually is discovered in the first six to eight weeks of pregnancy, and if left untreated, can cause organ damage and death.

"When we clinicians are confident of the diagnosis of ectopic pregnancy, we usually recommend either medications or surgery because the risks of doing nothing include bleeding to death," says Mary Jacobson, MD, chief medical director of Alpha Medical.

For most ectopic pregnancies the egg attaches to the uterus while the egg is still in the fallopian tubes. When this happens, it is known as tubal pregnancy and it accounts for 90% of ectopic pregnancies.

However, ectopic pregnancies can also occur in the:

• Cervix
• Ovary
• The middle layer of the uterine wall
• Abdominal cavity
• Within a cesarean section scar

Symptoms of an ectopic pregnancy

It is essential to seek medical attention immediately if you suspect you have an ectopic pregnancy. Here are the primary warning signs to look out for:

• Mid-abdominal or pelvic pain
• Pain in the low back
• Shoulder pain
• Abnormal vaginal bleeding
• Dizziness or feeling faint
• Mild pain on one side of the pelvis

Risk factors for having an ectopic pregnancy

While half of the people diagnosed exhibit no prior risk, there are factors that can increase your risk of developing an ectopic pregnancy.

For example, risk factors include:

• Over the age of 35
• Tubal surgery or damage
• Previous infection of the fallopian tubes from a sexually transmitted infection
• Exposure to DES, the first form of synthetic estrogen
• Use of an Intra-Uterine Device (IUD), a type of contraception
• Conception resulting from assisted reproduction technology, such as IVF

Other risk factors include:

• Smoking: Smokers were 1.73 times more likely to have an ectopic pregnancy than people who had never smoke.
• Alcohol: People who drank more than 10 grams per day — equivalent to about one standard beer or small glass of wine — were 1.5 times more likely to have an ectopic pregnancy.
• A history of ectopic pregnancy: If you've had one ectopic pregnancy, your risk of getting another one goes up by 10-27 percent. But that risk increases if you have a history of surgery, live birth, or spontaneous miscarriage.

How to treat an ectopic pregnancy

In an ectopic pregnancy the egg can not move into the uterus for a healthy pregnancy and, therefore, needs medical assistance to remove. You'll either receive medication or surgery, depending on the situation.

If you're given medication, it will likely be methotrexate — the same drug used for certain chemotherapy treatments. In the case of an ectopic pregnancy, methotrexate prevents the fetal cells from growing, and therefore, halts any further development. After four to six weeks, your body absorbs the fetal tissue and, in the case of a tubal pregnancy, leaves your fallopian tubes intact.

Methotrexate is used for women who are "not internally bleeding, have no history of kidney, liver, active lung disease, stomach ulcers, or immunodeficiency and should be willing and able to follow-up to care," says Jacobson.

The alternative option is laparoscopic surgery. Surgery is often necessary if you're more than a few weeks into the pregnancy because that can lead to heavy bleeding or a ruptured fallopian tube.

After these treatments, you may feel fatigued and have pain in your abdomen. And depending on the severity of the ectopic pregnancy, you may return to your normal cycle immediately or it may take several weeks for your periods — and fertility — to return.

In general, fertility is not affected as long as one of the fallopian tubes remains intact.

Loss of a pregnancy can be a difficult time. Reach out to your medical care provider if you need help with any physical or emotional distress after an ectopic pregnancy.

Related stories about pregnancy:

• You've had a miscarriage. Here's how long doctors recommend you wait before trying again
• Home pregnancy tests are very accurate, but there are a lot of ways you can get an inaccurate result
• Yes, Tylenol is safe for pregnancy. Here's the right dosage
• Can dogs sense pregnancy? Research doesn't have a definite answer
• Yes, you can get a flu shot while pregnant. Here's the best time to get it.
• Doctors debunk the 25 biggest pregnancy myths