Miscarriage or Period: How to Tell the Difference

Understanding the Causes, Risk Factors, and Early Signs of Miscarriage

Potential Signs of Miscarriage

Verywell / Melissa Ling  

Miscarriage is one of those things that sits in the back of a person's mind during pregnancy, and it’s a fair concern given that the rate of miscarriage can run anywhere from 10% to 20% among people who know they are pregnant. Three-quarters of miscarriages will occur during the first trimester. After 20 weeks, the rate drops to as low as 2%.

Signs and Symptoms of a Miscarriage

Signs of a miscarriage can include spotting or vaginal bleeding frequently, but not always, accompanied by abdominal cramping similar to menstrual cramps.

It's important to note that spotting and bleeding in early pregnancy is common, and often benign. While bleeding is not necessarily a sign of a miscarriage, it is important to have it checked out if it does happen. Generally speaking, if the bleeding is light and last for only a day or two, it is probably not a problem.

Heavier bleeding is another matter, particularly if it is accompanied by cramping. In some cases, there may also be back pain or the passing of tissue from the vagina. Morning sickness symptoms (nausea, vomiting) can also suddenly and inexplicably disappear.

Severe symptoms should never be ignored. Heavy bleeding accompanied by severe abdominal pain and/or dizziness could be the sign of an ectopic pregnancy and should be treated as a medical emergency.

This is not to say that all miscarriages will have symptoms, although many do. Some happen with little, if any, warning.

What Does Miscarriage Blood Look Like?

Bleeding that occurs during a miscarriage doesn't always look the same. It can be light pink or red, brown or black and grainy, or even look just like a normal period. If the loss occurs early in your pregnancy, there may be minimal clotting, but the farther the pregnancy has progressed, clots might be denser and larger and you might notice tissue that you don't normally see with a period.

Miscarriage bleeding tends to be heavier than bleeding during a menstrual period and could last longer than your period normally does. You should let your health care provider know if you fill more than two pads per hour for two consecutive hours.

What Is a Chemical Pregnancy?

While as many as one in five known pregnancies will result in a miscarriage, research suggests that the rate may be as high as 50% when including people who are unaware of their pregnancy.

Very early miscarriage (also known as chemical pregnancy) occurs when a pregnancy is lost shortly after implantation. This typically results in heavy bleeding which usually doesn't last any longer than your usual period. As such, it is possible that a late and/or especially heavy period could have, in fact, been a chemical pregnancy.

Whether or not this is important is debatable. In the end, unless there was a pregnancy test, there is really no way to know for sure if you’ve had a chemical pregnancy, and there could be any number of reasons for a heavy and/or late period.

Causes of First-Trimester Miscarriage

Among the miscarriages that occur in the first trimester, more than half will be the result of a chromosomal abnormality. These genetic abnormalities, in and of themselves, prevent the proper development of a fetus. As such, the miscarriage will have occurred not because the parents did anything "wrong;" it was simply the result of a pregnancy that couldn't be brought to term.

Other first-trimester causes can include a deficiency of progesterone, the hormone sometimes referred to as the "hormone of pregnancy." Without ample production of progesterone, the uterus is unable to properly accept and sustain the embryo during gestation.

Causes of Second-Trimester Miscarriage

There are several possible causes for miscarriage in the second trimester. Chromosomal and structural abnormalities of the fetus are factors in second-trimester miscarriages. But at this stage, a miscarriage is more commonly associated with the malformation of the uterus or the development of growths in the uterus (called fibroids).

Moreover, 20% of second-trimester miscarriages are caused by problems with the umbilical cord or a result of a placental abruption (the complete or partial separation of the placenta from the uterus) or placental previa (when the placenta covers the opening of the cervix).

Other factors can cause or contribute to the development of a miscarriage. These include:

  • Certain bacterial infections that can inflame the lining of the uterus
  • Certain chronic medical conditions like diabetes and thyroid problems
  • Excessive drug or alcohol use
  • Hormone problems
  • Immune system disorders, including antiphospholipid syndrome (APS)
  • Older age (since chromosomal abnormalities are more likely to occur in parents over 35)
  • Previous or multiple miscarriages
  • Smoking

After the 20th week, the loss of a pregnancy is no longer considered a miscarriage but is rather referred to as a stillbirth.

A Word From Verywell

If you think you are having a miscarriage, call your doctor immediately or go to your nearest emergency room. This is especially true if the bleeding is heavy, the pain is severe, or you are experiencing dizziness or have passed out.

Even if your symptoms are not severe, avoid sex and strenuous activity until you’ve been fully evaluated by your doctor and given the all-clear.

5 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. U.S. National Library of Medicine. Miscarriage.

  3. American Academy of Family Physicians. Early pregnancy loss.

  4. Hardy K, Hardy PJ. 1st trimester miscarriage: four decades of study. Transl Pediatr. 2015;4(2):189-200. doi:10.3978/j.issn.2224-4336.2015.03.05

  5. March of Dimes. Miscarriage.

By Krissi Danielsson
Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage.