Miscarriage Overview

Pregnant Woman Gazing Out Window
About 15 to 20 percent of recognized pregnancies end in miscarriage. Oscar Wong / Getty Images


A miscarriage -- a pregnancy that ends spontaneously before the fetus can survive -- is an often devastating event. About 15 to 20 percent of recognized pregnancies end in miscarriage, but almost 75 percent of those are attributed to chemical pregnancy. This type of miscarriage occurs very soon after the egg has implanted into the uterus. It can go unnoticed because the resulting bleeding often occurs at the time of a woman's period, and she may not realize she had been pregnant at all [source: American Pregnancy Association].


Miscarriages usually occur within the first 13 weeks of pregnancy. While the chance of a miscarriage in all pregnancies is approximately 15 to 20 percent, studies show that once a fetal heart function has been noted, the chance of miscarriage falls to less than 5 percent [source: MedicineNet].

Unfortunately, the miscarriage rate can change with the mother's health and age. Women between 35 and 45 have a 20 to 35 percent chance of a miscarriage, while women over the age of 45 have a 50 percent chance. Having a miscarriage also increases your chance of having another, but only slightly. A woman under 35 who has had one previous miscarriage carries a 25 percent chance of having another one [source: APA].



Causes of Miscarriage

Most American doctors recommend complete abstinence from alcohol during pregnancy.
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A miscarriage doesn't necessarily mean that there's a problem with the mother's reproductive function. The most common -- and unpreventable -- cause of first-trimester miscarriage is an abnormality in the fetus's chromosomes. This is usually a result of a mishap in the division process or an abnormal egg or sperm cell. But a miscarriage that occurs in the second trimester of pregnancy is usually related to an issue in the mother's reproductive system. Remember, though, this is just a general rule.

Hormonal factors include illnesses that involve an imbalance in the mother's hormone levels. Such illnesses include Cushing's syndrome, thyroid disease and polycystic ovary syndrome.


Not surprisingly, a poorly controlled chronic condition can have adverse effects on a pregnancy. Conditions like diabetes, if they're not taken care of properly, can increase the risks of miscarriage and birth defects. High blood pressure, lupus and an underactive or overactive thyroid can also cause problems.

Certain acute infections can be passed to the fetus or placenta and also put the mother at risk. In developing countries, malaria is a main cause of miscarriages. In these areas, pregnant women are two to three times more likely to get malaria than nonpregnant women [source: ­MedScape]. Malaria can also cause low birth weight, premature delivery and stillbirth. In developing countries, common infections include walking pneumonia, rubella, chlamydia, gonorrhea, herpes and toxoplasmosis, which can acquired from being around cat feces.

Abnormalities in a woman's reproductive anatomy can also cause a miscarriage. For example, some women may have a septum (dividing membrane) that separates the uterus into sections. Because this septum has poor blood supply, the placenta will have trouble growing, depriving the embryo of nourishment. Lack of muscle tone at the cervix (the opening of the uterus into the vaginal canal) also makes a miscarriage more likely. Many women develop uterine fibroids. Although they're benign, a poorly placed fibroid -- like one that blocks the embryo's implantation and blood supply -- can cause a miscarriage.

Lifestyle factors are also an important factor. Smoking has been shown to increase the risk of miscarriage. And it doesn't have to be the mother's smoking -- one study focused on fathers who smoke. It found that if the father smokes 20 or more cigarettes a day, the mother's risk of miscarriage increases by 81 percent [source: American Journal of Epidemiology]. Alcohol consumption during pregnancy is also harmful. One study showed that a mother who drinks more than 30 ounces of alcohol a month doubles her miscarriage risk. Another study showed that women who have more than three drinks a week in the first trimester had an increased risk of miscarriage. It is important to note that it has not been determined how much alcohol is safe during a pregnancy, and most American doctors recommend complete abstinence. And not surprisingly, the use of illicit drugs greatly increases the chance of miscarriage and birth defects [source: UpToDate Patient Information].

Some (not as conclusive) studies have shown an increased risk of miscarriage in women who drink excessive amounts of caffeine. Many doctors recommend limiting caffeine intake to 200 milligrams or less per day, which equals about two cups of coffee [source: March of Dimes].

It's just as important to consume the right things as it is to avoid the wrong things. Malnourished mothers also have an increased chance of miscarriage. Severly underweight women are often not healthy enough to get pregnant. And certain conditions that develop during pregnancy -- such as the rare illness hyperemesis gravidarum, which may result in severe malnutrition and dehydration -- can cause a woman to have excessive vomiting,

Finally, trauma can cause a miscarriage. It is important here to distinguish between physical trauma and emotional trauma. There is little proof that emotional trauma -- fear, grief, anger or stress -- results in an increased risk of miscarriage. However, physical trauma does greatly increase the risk. This includes surgeries that could possibly compromise the safety of the uterus. These types of procedures are usually performed only in emergency situations.

On the next page we'll look at the warning signs of a miscarriage.­


Miscarriage Warning Signs

Severe back pain can be a sign of miscarriage.
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There are often warning signs before a miscarriage actually occurs. It is important for pregnant women, as well as those planning to get pregnant, to know the most common of them.

  • Bleeding can range from mild to severe and can be brown or bright red in color. In some cases, women may have several bouts of bleeding. But it doesn't always mean that a miscarriage will soon follow. Up to 30 percent of all pregnancies involve some level of bleeding. In fact, studies have shown that as long as there is fetal cardiac activity, approximately 96 percent of pregnancies in which the mother experiences vaginal bleeding between seven and 11 weeks do not miscarry [source: American Pregnancy Association].
  • Mild to severe back pain and cramping is another common warning sign. The location of the cramps can vary widely and can be felt on one or both sides or in the middle of the abdomen. They usually occur in the lower abdomen but can move to the lower back.
  • Both mucus and clotlike vaginal discharge are symptoms of a miscarriage. The mucus is usually white to pink in color. Again, this is not necessarily a sign of inevitable miscarriage, but any tissue that passes through the vagina should be saved in a sterile container and brought to the doctor's office for examination.
  • Oftentimes, one of the first warning signs of a miscarriage is a decrease in pregnancy side effects. This can mean weight loss, absence of nausea or breasts that are no longer tender. A word of caution should be used here -- some of these symptoms, like weight loss in early pregnancy, may be normal for some women. But any woman experiencing these symptoms should consult her doctor.
  • Contractions are extreme pains that usually occur every five to 20 minutes.

If a woman does experience one of these symptoms, her doctor will usually perform an examination to determine how the pregnancy is progressing. This exam can consist of an internal pelvic examination, an ultrasound and blood tests. The internal exam is performed to establish if the cervix is dilated. If it isn't, the pregnancy usually continues. But if the cervix is dilated, a miscarriage is normally inevitable. An ultrasound can find a fetal heartbeat and assess if the fetus is developing normally. Finally, blood tests can determine if pregnancy hormones are still at the expected levels.


J­ust as there are many warning signs of a miscarriage, there are many different types of miscarriages. We'll discuss them in our next section.


Types of Miscarriage

An ultrasound can reveal a missed miscarriage.
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Health care providers use the blanket term "miscarriage," so it may be surprising to learn that there are several different types.

Threatened: Sometimes a woman will experience vaginal bleeding in the early months of pregnancy. This bleeding is usually mild and may be accompanied by cramps or backaches. But the cervix remains closed and, as the name suggests, the miscarriage is not successful. In fact, the majority of pregnancies continue successfully after a threatened miscarriage.


Inevitable: This occurs when a woman experiences vaginal bleeding in conjunction with back or abdominal pain. In this type, the cervix is open, or dilated, and some of the uterine membranes may be ruptured. In these cases, the miscarriage has already begun.

Incomplete: An incomplete miscarriage results when only part of the pregnancy has been miscarried, leaving some products of conception in the womb. Symptoms often include heavier bleeding and severe abdominal pain after tissues have expelled from the womb. An ultrasound usually reveals the remaining tissue.

Complete: A complete miscarriage includes the expulsion of all products of conception, including the fetus and the placenta. While symptoms are similar to those seen in incomplete miscarriages, they subside quickly after the tissue is expelled. An ultrasound is often performed to ensure that no tissues remain and the womb is empty.

Missed: Basically, this is a miscarriage that the woman wasn't aware even happened. In these cases, there is embryonic death but the woman's body does not expel the tissues. So, cramping, bleeding and back aches are not present, and the only symptoms are loss of pregnancy symptoms such as nausea, weight gain and breast tenderness. These types of miscarriages are generally discovered when the fetal heartbeat isn't located during a routine doctor's visit.

Recurrent: Only about 1 percent of women have three or more first-trimester miscarriages [source: Royal College of Obstetricians and Gynaecologists].

Septic: A septic miscarriage can risk the health, and sometimes life, of the expectant mother. This type of miscarriage occurs as a result of either a missed or incomplete miscarriage. After the miscarriage, some or all of the remaining pregnancy tissue becomes infected. This tissue then infects the uterus, which can result in the spread of the infection throughout the body. Symptoms of this type of miscarriage can include vaginal bleeding, abdominal pain, fever, chills, exhaustion and a thick, foul-smelling vaginal discharge.

­No matter the type, the treatment for most of the miscarriages described above is similar. We will focus on all the treatments for miscarriages in the next section.­


Miscarriage Treatment

After a miscarriage, your doctor can advise when it will be safe to try for another baby.
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Post-miscarriage treatment focuses on preventing further blood loss or infection. Of course, the goal of therapy is different for women who have suffered a threatened miscarriage. In these cases, prevention of further complications is key and may include bed rest or a reduction of activity.

Treatment depends on the type of miscarriage and when in the pregnancy it occurred. If it was early, additional treatment isn't usually required because all of the fetal tissue is usually expelled by the body. When a woman has suffered an incomplete or missed miscarriage, a procedure known as a dilation and curettage, or D&C, is performed to retrieve the tissues from the womb and stop any further bleeding or infection.


If a woman is in the process of having an inevitable miscarriage, she can have a D&C or wait and let the miscarriage occur naturally. She can choose the latter option if she was in the first trimester of pregnancy, has no signs of infection and has stable vital signs. Her body will usually expel the tissues within two weeks. Patients who prefer to miscarry this way should return to their doctor to confirm that all the tissues have been expelled. Another option is medication that helps the uterus expel the pregnancy, which usually works within a few days.

Even though a live birth has not taken place, women do need to receive certain medications after a miscarriage that relate to the fetus. For example, if the mother and the fetus have incompatible blood types, this could cause complication in any later pregnancies. If the mother is Rh factor negative, she will receive a shot called RhoGAM, which works to prevent any blood-type interaction between the woman and her miscarried pregnancy. This will protect a future fetus. If the mother doesn't get the shot, her Rh-negative blood can cross over to the fetus and cause complications. Antibiotics are also often used to reduce the chance of infection or to fight a current infection. Finally, the mother could require medication if she has been bleeding for a prolonged period -- and she should also be aware of symptoms of an infection, which can occur as late as six weeks after the miscarriage. These signs include fever, severe pain, heavy bleeding and chills.

After a miscarriage a women is usually encouraged to avoid putting anything in the vagina, like tampons or douches. Also, sex is discouraged immediately following a miscarriage. However, contraception, including IUDs, can be used again immediately, and a woman's period usually returns within four to six weeks. Studies are not clear on a safe waiting period between a miscarriage and a new pregnancy, but doctors usually advise waiting two to three months.

Some miscarriages are simply unavoidable, but there are a few things that expectant mothers can do to avoid one. We'll discuss them in the next section.


Treating the Emotional Pain of a Miscarriage

A woman's physical health is important during and after a miscarriage, but her emotional health should not be ignored. The loss of a pregnancy can be felt just as strongly as a loss of a child. Women can also experience postpartum depression after a miscarriage. There is a wide variety of emotional treatments, including grief counseling, depression or anxiety medications, or simply opening up to friends and family. There are plenty of resources out there to help both the expectant mother and her partner.

Here are a few common tips for dealing with the loss of pregnancy:


  • Decide for yourself. Well-meaning friends and family will suggest ways to deal with your pain, but right after the miscarriage, don't do anything that makes you feel uncomfortable, such as returning baby clothes.
  • Take your time. There is no set time limit on how long you can grieve. As the cliché says, take it one day at a time and do things on your schedule.
  • Know your triggers. Seeing a baby, going to a baby shower or even walking past the Baby Gap could cause a swelling of emotion. It's OK to avoid these situations until you feel strong enough to handle them.
  • Postpone major decisions. When you're experiencing an especially emotional time, big decisions -- like buying a house, selling a car or changing your career -- should be delayed.
  • Don't cut your partner off. Keep the lines of communication open.
  • Set up a support network. While some friends and family may not understand the degree of your grief, and many are sure not to know what to say, they will all probably offer support. Many women also find comfort in going to support groups or joining an online chat group­.



How to Prevent a Miscarriage

Leafy greens are a great source of folic acid.
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The first, and perhaps most important, step in a healthy pregnancy is getting prenatal care. This means finding an obstetrician right after a positive pregnancy test. The doctor will recommend prenatal vitamins, which are rich in many nutrients expectant mothers need, like calcium, iron and folic acid. Folic acid is especially important in the first few weeks of pregnancy, when the fetus is developing its neural tube, which eventually develops into the brain and spinal cord. A lack of folic acid during this period can result in birth defects. The recommended daily amount is 400 micrograms. There is enough folic acid in prenatal vitamins, and even in some multivitamins, but you can't get too much of it, so a healthy diet with foods rich in folic acid is recommended as well.

Between doctor's visits, pregnant women should follow a healthy diet, exercise on a regular basis, keep their "baby weight" within healthy limits, and try to manage stress levels. Many doctors believe that good health should begin before you even conceive in order to ensure the healthiest pregnancy possible. In fact, taking folic acid even before you get pregnant can help prevent birth defects.


­While there are plenty of vitamins and foods that you should ingest, there are a few things expectant mothers should avoid. They shouldn't smoke or even be around smoke. Either of these behaviors doubles the risk of placental problems and low birth weight. It also increases the risk of having a premature baby. However, there is good news. If a woman quits smoking during her first trimester, the risk returns to that of a woman who never smoked. Other things to avoid while pregnant include excessive amounts of caffeine, exposure to X-rays and, of course, contact sports or other dangerous physical activities [source: March of Dimes].

It's also important for any woman who may suffer from a chronic health condition to take extra special care of herself. Women with high blood pressure should start checking their pressure at home and discussing medication changes with their doctors. Also, women with diabetes should check their blood sugar several times a day and adjust their insulin or oral medications as needed. Finally, pregnant women should treat any bacterial or viral infections. Some viral infections, like chlamydia or herpes, can determine if baby will be born vaginally or via Caesarean section.

For more information on miscarriages, follow the links on the next page.


Lots More Information

Related HowStuffWorks Articles

More Great Links

  • American Journal of Epidemiology: Paternal Smoking and Pregnancy Loss. http://aje.oxfordjournals.org/cgi/content/full/159/10/993
  • American Pregnancy Association: Miscarriage. http://www.american­pregnancy.org/pregnancycomplications/miscarriage.html
  • American Pregnancy Association: Prenatal Vitamins. http://www.americanpregnancy.org/pregnancyhealth/prenatalvitamins.html
  • Discovery Health: Miscarriage Facts. http://health.discovery.com/centers/pregnancy/americanbaby/miscarriage.html
  • EMedicine: Miscarriage. http://www.emedicinehealth.com/miscarriage/article_em.htm
  • J Midwifery Womens Health Journal: Spontaneous and Induced Abortion in Developing Countries. http://www.medscape.com/viewarticle/560965_2
  • March of Dimes: Caffeine in Pregnancy. http://www.marchofdimes.com/professionals/14332_1148.asp
  • March of Dimes: Folic Acid. http://www.marchofdimes.com/pnhec/173_769.asp
  • March of Dimes: Miscarriage. http://search.marchofdimes.com/cgi-bin/MsmGo.exe?grab_id=2&page_id=10289664&query=miscarriage&hiword=MISCARRIAGES+MISCARRIED+miscarriage+
  • March of Dimes: Smoking During Pregnancy. http://search.marchofdimes.com/cgi-bin/MsmGo.exe?grab_id=2&page_id=3151104&query=smoking&hiword=­smoking+
  • Mayo Clinic: Understanding Miscarriages. http://www.mayoclinic.com/health/miscarriage/PR00097
  • Medicine Net: Miscarriage. http://www.medicinenet.com/miscarriage/article.htm
  • ­MedS­­cape. "Spontaneous and Induced Abortion in Developing Countries." http://www.medscape.com/viewarticle/560965_2
  • Royal College of Obstetricians and Gynaecologists: The Investigation and Treatment of Couples with Recurrent Miscarriage. http://www.rcog.org.uk/resources/Public/pdf/Recurrent_Miscarriage_No17.pdf
  • UpToDate: Patient Information - Miscarriage. http://patients.uptodate.com/topic.asp?file=pregnan/5386