Miscarriage Facts

Anai Rhoads's picture

by Anai Rhoads

If you don't see your question here, look in "Grief and Loss's" frequently asked questions.

Intercourse, falling, and exercise does not typically cause a miscarriage. The fetus is well protected by the mother's bones and muscle as well as by the amniotic fluid. There is also no evidence that conceiving while taking birth control pills increases the risk of miscarriage. Becoming pregnant while using an IUD, however, does make you more likely to miscarry or develop an infection.

As many as 25 percent of all pregnancies end in miscarriage, half of them before the woman even realizes she is pregnant. Fortunately, most women who miscarry, even more than once, can become pregnant again and give birth to a healthy baby.

What are the warning signs?

Any bleeding from the vagina during pregnancy suggests the possibility of miscarriage. Call your doctor about any abnormal vaginal bleeding, even if you do not think you are pregnant. Bleeding or spotting may be the first sign that you are pregnant and that the pregnancy is at risk. Staining or bleeding does not necessarily mean that you will miscarry, however. About 15 to 25 percent of pregnant women have some spotting or bleeding early in pregnancy, and about half of these pregnancies carry successfully to term.

Bleeding that signals possible miscarriage is usually light. It can be brown or bright red and may repeatedly occur over many days. If the bleeding persists or increases, the chances of losing the baby are greater. Cramping or low backache usually develops at some point after the bleeding has started.

If you have been bleeding and an ultra sound scan (sonogram) indicates that the fetus is alive, your doctor probably will ask you to rest in bed as much as possible and avoid sexual activity. The doctor will monitor you to be sure that:

•Your cervix is closed (If it's open, it's more likely you will miscarry).
•He or she will check the discharge/blood for clotting that would indicate whether or not it contains the fetus.
•You will be given a sonogram to see if there are any fetal heart movements, and if the fetus is growing properly.

More than 90 percent of first trimester pregnancies continue when ultra sound scans indicate that the baby is alive.

Rarely, early in pregnancy, fluid is suddenly released from the vagina without bleeding or pain. If you experience this, call your doctor immediately. You will probably be instructed to stay in bed and watch for further discharge, bleeding, cramping, or fever.

Inevitable Miscarriage

When bleeding and pain are accompanied by the breaking of membranes (the amniotic sac surrounding the fetus) and the widening of the cervix, the pregnancy is viewed as an inevitable miscarriage. Uterine contractions to expel the fetus usually begin soon after these symptoms develop.

Incomplete and Missed Miscarriages

In some miscarriages, the body does not expel all the of pregnancy. This is called an incomplete miscarriage. In about 2 percent of pregnancies, the body does not discharge the fetus or placenta for several weeks, even though the fetus has died. This is known as a missed miscarriage. This can happen while a woman has neither menstrual periods nor any signs of pregnancy. Breasts may return to their pre-pregnancy state, or the woman may lose a few pounds. (Note: Not all missed miscarriages are preceded by warning signs).

An incomplete or missed miscarriage that takes place early in pregnancy is usually removed with either suction or dilation and curettage (D&C) - "opening" the uterus and scraping out its contents, through the vagina, with an instrument called a curette. These procedures not only clear the uterus but also prevent infection. When incomplete miscarriage occurs later in pregnancy, the doctor may have to induce labor to remove the fetus.

How can I minimise the risk?

Most miscarriages are caused by chromosomal (genetic) abnormalities and other physical factors that are beyond your control. There are, however, steps you can take to reduce the risk of losing a pregnancy.

•Smoking increases the risk of losing a genetically normal baby. One study showed that women who smoked more than 10 cigarettes a day were about twice as likely to miscarry, regardless of their age. The risk of losing a pregnancy increases with the number of cigarettes a woman smokes.
•Don't drink alcoholic beverages. Having an alcoholic drink twice weekly doubled the risk of losing normal babies in one study; drinking alcohol every day tripled the risk of such miscarriages. Similarly, consuming large amounts of caffeine, more than 3-4 cups of coffee per day (or the equivalent in other substances that contain caffeine, such as chocolate, or tea) slightly increases the chance of miscarriage.
•Avoid radiation and poisons. Exposure to high levels of radiation or toxic substances increases the risk of miscarriage. Arsenic, lead, formaldehyde, benzene, and ethylene oxide can cause miscarriage. Make sure you are not exposed to these substances at work, home or anywhere else while pregnant or trying to conceive.
•Prevent trauma to the abdomen. Injuries from the steering wheel or seat belt in a car, especially during the second trimester, sometimes cause miscarriage.
•Certain prescription and over-the-counter drugs are associated with fetal abnormalities and miscarriages. Consult your doctor before taking any medication when you are pregnant or trying to conceive. Some drugs can damage the fetus and cause miscarriage before you even know you are pregnant. Check out ALL medications with your doctor.

What are the causes of miscarriage?

In general, miscarriage is more common in women over 35 years old and in pregnancies involving more than one fetus. In some multiple pregnancies (twins, triplets, or more), one or more of the fetuses survives even after another one dies. The dead fetus is expelled from the mother's body when the surviving baby is born.

About 1 in 200 women has repeated miscarriages, which physicians call recurrent spontaneous abortion. In many cases, even these miscarriages happen by chance and do not signal a problem in either or both partners. Often no cause is found.

Chromosomal Abnormalities -- Problems in the chromosomes of the embryo, by far the most common reason for loss of pregnancy, are found in more than half of miscarriages occurring in the first 13 weeks. Miscarriages apparently eliminate about 95 percent of fertilized eggs or embryos with genetic problems - perhaps nature's way of ending a pregnancy in which the child would be unable to survive. Spontaneous abortions of this type usually occur before the woman knows that she is pregnant.

Sometimes, however, chromosomal abnormalities are caused by the parent's genes. This is more likely if the woman has had repeated miscarriages or if either parent has relatives or a child with birth defects. Genetic testing of fetal material from the miscarriage can help the doctor identify the problem.

Immune System Problems -- Some women have repeated miscarriages because their bodies see each baby as an invading organism and attack it with antibodies. Ordinarily, many elements of the immune system work together to ensure that the mother's body does not reject the baby. But when this coordination fails, a miscarriage follows. Treatments for such problems in the immune system are experimental and should not be tried until other causes for repeated miscarriage have been ruled out.

Hormone Imbalance -- Some women do not make enough progesterone, the hormone that prepares the lining of the uterus to nourish a fertilized egg; and if the uterine lining cannot sustain an egg, miscarriage will occur. Progesterone supplements, given by injection or in vaginal or rectal suppositories, can correct this problem. The medication can also make it more difficult for a dead fetus to be expelled. A blood test and a biopsy of a small amount of tissue taken from the uterine lining can determine whether you are producing enough progesterone naturally.

Illness -- Miscarriages are much less common in the third trimester. Those that occur are more likely to be due to maternal factors, such as an illness in the mother, than to genetic abnormalities in the baby.

Women with poorly controlled diabetes are at great risk for miscarriage. Those whose diabetes is controlled, however, whether it existed before the pregnancy or developed after conception (gestational diabetes), are no more likely to lose a pregnancy than other women. A woman may not know that she has diabetes, however, until it is discovered during a search for the cause of repeated miscarriages. The routine blood and urine tests given during pregnancy are an effort to identify this problem while it still can be remedied.

Other diseases and conditions linked to increased risk of miscarriage include systemic lupus erythematosus (SLE, or lupus), high blood pressure, and certain infections, such as rubella (German measles), herpes simplex, and chlamydia. Experts disagree about the role of hypothyroidism, or an underactive thyroid gland, in miscarriage, but it is likely that a severe case increases the risk.

Abnormalities of the Uterus and Cervix -- Anything physically wrong with the uterus or cervix can lead to a miscarriage. Fibroids -- noncancerous growths made of uterine muscle tissue -- can also be at fault as can a weak cervix that widens too early in pregnancy without any warning signs of labor, releasing the fetus from the uterus.

These physical problems account for up to 15 percent of repeated miscarriages. To diagnose such problems, the doctor may inject the cavity of the uterus with some fluid, then take an x-ray of your uterus and fallopian tubes. Another technique is to examine the inside of your uterus through a long, thin instrument (hysteroscope) inserted through the vagina and cervix. In another procedure, the doctor may make a small incision in the lower abdomen and insert a laparoscope, through which he or she can inspect the pelvic organs. Surgery can correct many abnormalities in the uterus, but your doctor probably will not recommend it until all other causes of miscarriage have been ruled out. After surgery, 75 to 95 percent of pregnancies are successful.

Though a weak cervix is a relatively rare condition, it is almost impossible to detect before it becomes apparent during pregnancy, usually after the 15th week. Once discovered, it is likely to disrupt every pregnancy. To remedy the problem, after the first trimester, but before the cervix has dilated (widened) to a certain point, your doctor can reinforce the cervix with sutures, which will be removed when the baby reaches term. Women with bleeding, uterine contractions, or ruptured membranes are not advised to undergo this procedure.

After Miscarriage

Miscarriages due to random natural factors are so common that they are not considered medically significant until you have had 3 in a row. At that point, the problem is officially classified as "habitual abortion," and your doctor will recommend a complete diagnostic work-up.

The investigation will probably start with a detailed interview. Which tests are performed will depend on your own personal and medical history, the father's history, and how many miscarriages you have had. You will be tested for infections of various kinds, possibly including sexually transmitted diseases. Blood tests may be done for hormonal problems or a malfunction in the immune system. You and your partner may be tested for chromosomal abnormalities and genetic diseases as well. The lining of your uterus may be analyzed from a small sample. The doctor may order an internal ultra sound of your uterus and fallopian tubes to look for fibroids, blockage, or scar tissue.

Unless the problem involves autoimmune antibodies, chromosomal abnormalities, or a weak cervix, there is a 70 to 85 percent chance of success, even after 4 miscarriages.

Sex can be resumed safely within 4 to 5 weeks after miscarriage. A woman's body usually is prepared for another pregnancy after 1 or 2 normal menstrual periods. Ovulation can occur as little as 2 weeks after a miscarriage.

Give yourself enough time to recover emotionally from your loss before facing the challenges of another pregnancy. As with any major life event, it is important to balance the need to grieve with the need to move on. And remember, most couples who experience a miscarriage can go on to have a healthy baby.

Miscarriage in the Second Trimester

The risk of ectopic pregnancy is almost nil beyond the 12th week of pregnancy, while the risk of miscarriage really dramatically drops by this stage.

Late Miscarriage -- Between the third month and 20th week of pregnancy, a spontaneous abortion is known as a late miscarriage. The symptoms are similar to the first trimester miscarriage. In many cases, an incompetent cervix is responsible. This is when the cervix dilates prematurely and cannot carry the fetus. This is also known as a weak cervix. Trauma to the cervix as a result of infection, for example, can trigger premature dilation.

If an incompetent cervix is caught early enough, the cervix can be stitched up and the pregnancy can be saved. Around 38 weeks prior to labor, the stitches can be removed and a normal vaginal birth can take place.

If the miscarriage is inevitable and can't be prevented, a D & C can be performed up until the 20th week. A miscarriage after 20 weeks is no longer a miscarriage but now called a premature birth, or worse -- stillbirth.

Premature Labor

The symptoms of premature labor are: contractions accompanied by vaginal bleeding, vaginal discharge, lower back pain, and vaginal pressure anywhere from the 20th week to the 37th week. Premature rupture of the membranes (the amniotic sac) occurs in 20-35% of all premature deliveries.

What causes premature labor?

The causes of premature labor at this stage are not known, but there are some factors that can trigger it:

•Smoking
•Inadequate nutrition
•Diabetes
•Thyroid problems
•Sexually transmitted diseases
•Recreational drugs
•Medication not prescribed by your doctor
•Alcohol
•Placental problems
•Physical trauma

If your doctor is successful in stopping the contractions with medication, you may be put on strict bed rest for the duration of your pregnancy. On the other hand, if your membranes have ruptured or you any have any vaginal bleeding, there is little chance you can stop the labor; you will need to go ahead and deliver.

Miscarriage Statistics

Some tables indicating the risk of miscarriage for various groups are presented below.


Age and miscarriage

Age Percentage
20-29 years old 12% risk of miscarriage
45 or older 52% risk of miscarriage




Gestation and miscarriage

When miscarriage Stats
Miscarriage before 12 weeks 4 in 5
Miscarrying after 12 weeks of pregnancy 1 in 30
Miscarriage with abnormal chromosomes 1 in 2
When previous miscarriage had abnormal chromosomes 1 in 1.25




Ectopic pregnancy

General Risk 1 in 66 pregnancies
With PID 1 in 9 pregnancies
Over age 34 1 in 27 pregnancies
Previous ectopic 1 in 6 pregnancies




Increases after exposure to chemical solvents


Chemical Risk
perchlorethylene (dry cleaning) 4.8 times greater risk
trichloroethylene (dry cleaning) 3.3 times greater risk
paint thinners 2.6 times greater risk
paint strippers 2.7 times greater risk
glycol ethers (found in paints) 3.0 times greater risk

Anai Rhoads is a medical and political researcher/writer with a particular interest in the sanctions on Iraq and the wider effect of racism's influence in the Middle East. A vegan since 2000, she is a dedicated supporter of activities which promote animal and human rights. Originally from Greece, she now resides in Virginia, USA with her husband and their two dogs, Bijou and Eva.

*Reproduction must be authorized in writing only, and altering the material and this copyright is prohibited and protected by international law.

Copyright © Anai Rhoads. Permission to republish granted to Pregnancy.org, LLC.