Pregnancy loss may be more likely during the early weeks of pregnancy. It can occur for different reasons, including genetics and infections, among other causes.


Miscarriage is a word used to describe the early loss of a pregnancy before 20 weeks of pregnancy. It usually happens in the first trimester.

Unfortunately, between 10 and 15 percent of known pregnancies end in miscarriage.

You may have heard of couples waiting to announce a pregnancy until the risk of having a miscarriage is lower. The further you are into the pregnancy, the less likely you are to miscarry.

Read on to learn about what causes miscarriages and the risk for miscarriage during pregnancy.


Dr. Kaylen Silverberg, a Texas-based fertility specialist, says miscarriages are very common.

“Women think that when they have one miscarriage, they are doomed to miscarry again,” he says. However, the likelihood of having recurrent miscarriages (at least 2 or 3) is low, only occurring in about 1 percent of women.

Studies have shown an increased risk for miscarriage in women who have had recurrent miscarriages in the past. Conversely, some studies indicate that having a successful pregnancy before a current pregnancy may decrease the risk for miscarriage in the current pregnancy.

Several factors have to be accounted for in these cases, however. This includes maternal age and other medical conditions present. Most doctors will begin to investigate for a cause after you have had two to three losses. This will include reviewing your medical history in detail and performing certain tests.

Here are the five most common miscarriage causes.


When the sperm and egg meet, the cells come together. They then begin to divide to start forming the genetic material that makes up a person.

Each of us is supposed to have 46 total chromosomes. That’s 23 from one parent and 23 from the other. If something goes wrong when the cells are dividing, a chromosome may be missing or repeated.

About 50 percent of all first trimester miscarriages are because of chromosomal abnormalities. This can occur more frequently in women who are considered advanced maternal age, or greater than 35 years old at pregnancy term.


Uterus or cervix infections can be dangerous to a developing baby and lead to miscarriage. Other infections that may pass to the baby or placenta can also affect a developing pregnancy and may lead to loss.

Some of these infections include:

Anatomic problems

This refers to defects of the uterus cavity. If a woman’s uterus didn’t form correctly when she was developing, it may be unable to support a healthy pregnancy.

Clotting disorders

Clotting disorders are conditions that cause your body to form more blood clots than normal. Examples include lupus anticoagulant and antiphospholipid syndrome.

In the case of pregnancy, blood clots can form in the placenta. This prevents nutrition and oxygen from getting to the baby-to-be, and prevents waste from being carried away.

Risk rates

The first trimester of pregnancy is considered weeks 0 to 13. About 80 percent of miscarriages happen in the first trimester. Losses after this time occur less often. March of Dimes reports a miscarriage rate of only 1 to 5 percent in the second trimester.

Weeks 0 to 6

These early weeks mark the highest risk of miscarriage. A woman can have a miscarriage in the first week or two without realizing she’s pregnant. It may even seem like a late period.

Age plays a role in a woman’s risk factor. One study indicated that compared to women younger than 35:

  • Women ages 35 to 39 have a 75 percent increase in risk
  • Women ages 40 and older are at 5 times the risk

Weeks 6 to 12

Once a pregnancy makes it to 6 weeks and has confirmed viability with a heartbeat, the risk of having a miscarriage drops to 10 percent. According to a 2008 study, the risk for miscarriage falls quickly with further gestational age. However, this was not specifically studied in patients with other risk factors for miscarriage.

Weeks 13 to 20

By week 12, the risk may fall to 5 percent. But keep in mind that it doesn’t really fall below that because complications can happen during pregnancy.

Signs and symptoms

The most common signs of a miscarriage are bleeding and cramping that are felt in the abdomen, pelvis, or lower back.

Some women have spotting (light bleeding) during pregnancy. A few drops or light flow of brown or dark red doesn’t necessarily mean trouble. But call your doctor right away if you see bright red blood, particularly in large amounts.

Cramping can also happen in normal pregnancies. But if it’s severe or occurring more on one side of the pelvis, you should call your doctor.


The majority of miscarriages are the result of genetic abnormalities or other health factors that are beyond our control. For that reason, there isn’t a whole lot you can do for prevention.

The best thing you can do is to keep yourself as healthy as possible before trying to conceive and throughout your pregnancy. Here are some tips to staying healthy during pregnancy:

  • Eat a well-balanced diet.
  • Exercise regularly.
  • Avoid alcohol, recreational drugs, and cigarette smoking.
  • Reduce caffeine to 200 mg or less per day.
  • Get regular prenatal visits.

If you’re worried about your risk of having a pregnancy affected by chromosomal issues, you can speak to your doctor about genetic testing before trying to conceive. A blood sample will be taken from one or both partners, and then sent to a laboratory to be evaluated for major genetic disorders. This testing and other evaluation are generally done after someone has recurrent losses.

The takeaway

The experience of a miscarriage can be physically and emotionally painful. But it’s important to remember that it’s not your fault. Talk to trusted friends and family, and ask for help when you need it.

Your doctor may be able to recommend a support group or therapist in your area. There are also many online organizations and support groups like March of Dimes that offer a safe place to share your story and grieve with others.

Rena Goldman is a journalist and editor who lives in Los Angeles. She writes about health, wellness, interior design, small business, and the grassroots movement for campaign finance reform. When she’s not glued to a computer screen, Rena likes to explore new hiking spots in Southern California. She also enjoys walking in her neighborhood with her dachshund, Charlie, and admiring the landscaping and architecture of LA homes she can’t afford. Follow her on Twitter: @ReeRee_writes