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 25 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 for a breakdown of what causes miscarriages. The risk decreases as the pregnancy progresses.


Dr. Kaylen Silverberg, 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.

But it turns out that your risk isn’t any greater after a miscarriage. Even after two miscarriages, the risk of miscarrying again doesn’t increase.

He says most medical professionals don’t evaluate a woman until she’s had three miscarriages. But there are fertility experts who will do an examination after two.

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.

According to Dr. Silverberg, 90 percent of all first trimester miscarriages are because of chromosomal abnormalities.


Uterus or cervix infections can be dangerous to a developing baby and lead to miscarriage.

Some of these infections include:

  • chlamydia
  • gonorrhea
  • mycoplasma
  • ureaplasma

Anatomic Problems

 This refers to defects of the uterus cavity. If the 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.

Progesterone Deficiency

In luteal phase deficiency or progesterone deficiency, the body isn’t producing enough progesterone. This is the hormone that plays a big part during pregnancy.

Risk Rates

The first trimester of pregnancy is considered weeks 0 to 13. About 80 percent of miscarriages happen in the first trimester.

Weeks 0 to 7

These weeks mark the highest risk. A woman can have a miscarriage in the first week or two without even realizing she’s pregnant. She might think it’s a late period.

Age plays a role in a woman’s risk factor. Here is the miscarriage risk breakdown by age:

  • Women age 20 to 30: 9 to 17 percent
  • Women age 35 to 39: 20 percent
  • Women age 40 to 44: 40 percent
  • Women age 45 and older: 80 percent

Weeks 7 to 12

Once a pregnancy makes it to 7 weeks with a heartbeat, the risk of having a miscarriage drops to 10 percent.

Weeks 12 to 20

By week 12, the risk may fall to 5 percent. But keep in mind that it doesn’t really go 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 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 the doctor right away if you see bright red blood, particularly in large amounts. Cramping can also happen in normal pregnancies.


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 and cigarette smoking
  • avoid caffeine
  • get regular prenatal visits

If you’re worried, you might want to try genetic testing before trying to conceive. Blood is taken from both partners. It’s sent to a laboratory to be evaluated for major genetic disorders.

The Takeaway

It’s important to remember if you have a miscarriage, it’s not your fault. The experience can be physically and emotionally painful. 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.