Miscarriage: Signs, symptoms, and causes

What is a miscarriage?

Miscarriage is the loss of a pregnancy in the first 20 weeks. In medical language, the term "spontaneous abortion" is often used in place of miscarriage. When it happens in the first trimester, miscarriage is also called early pregnancy loss.

About 10 to 20 percent of known pregnancies end in miscarriage, and more than 80 percent of these losses happen before 12 weeks. The risk of miscarriage drops significantly as pregnancy progresses. In one study, researchers found a miscarriage rate of 9.4 percent at 6 weeks of pregnancy, 4.2 percent at 7 weeks, 1.5 percent at 8 weeks, 0.5 percent at 9 weeks and 0.7 percent at 10 weeks.

This doesn't include situations in which you lose a fertilized egg before a pregnancy becomes established. Studies have found that 30 to 50 percent of fertilized eggs are lost before or during the process of implantation – often so early that a woman goes on to get her period at about the expected time or up to a week late. This is called a chemical pregnancy.

Signs of miscarriage

If you have these signs of miscarriage, call your doctor or midwife right away so they can determine whether you have a problem that needs to be dealt with immediately:

• Bleeding or spotting. Vaginal spotting or bleeding is usually the first sign of miscarriage. Keep in mind, though, that up to 1 in 4 pregnant women have some bleeding or spotting (finding spots of blood on your underpants or toilet tissue) in early pregnancy, and most of these pregnancies don't end in miscarriage.
• Abdominal pain. Abdominal pain usually begins after you first have some bleeding. It may feel crampy or persistent, mild or sharp, or may feel more like low back pain or pelvic pressure.

If you have both bleeding and pain, the chances of your pregnancy continuing are much lower. It's very important to be aware that vaginal bleeding, spotting, or pain in early pregnancy can also signal an ectopic or a molar pregnancy.

Also, if your blood is Rh-negative, you may need a shot of Rh immune globulin within two or three days after you first notice bleeding, unless the baby's father is Rh-negative as well.

Some miscarriages are first suspected during a routine prenatal visit, when the doctor or midwife can't hear the baby's heartbeat or notices that your uterus isn't growing as it should be. (Often the embryo or fetus stops developing a few weeks before you have symptoms like bleeding or cramping.)

If your practitioner suspects that you've had a miscarriage, they'll order an ultrasound to see what's going on in your uterus. They may also do a blood test.

What causes miscarriage?

There are a lot of myths about what causes miscarriage. But things like stress, exercising, having sex, and having used birth control pills before getting pregnant don't cause miscarriage. Neither does morning sickness, a fall, or a blow to the stomach. Don't blame yourself. Miscarriage usually happens because the fertilized embryo can't develop normally.

Between 50 and 70 percent of first-trimester miscarriages are thought to be random events caused by chromosomal abnormalities in the fertilized embryo. Most often, this means that the egg or sperm had the wrong number of chromosomes.

Sometimes a miscarriage is caused by problems that occur during the delicate process of early development. This would include an egg that doesn't implant properly in the uterus or an embryo with structural defects that prevent it from developing.

Since most healthcare practitioners won't do a full-scale workup of a healthy woman after a single miscarriage, it's usually impossible to tell why the pregnancy was lost. And even when a detailed evaluation is performed – after you've had two or three consecutive miscarriages, for instance – the cause still remains unknown half the time.

When the fertilized egg has chromosomal problems, you may end up with what's sometimes called a blighted ovum (now usually referred to in medical circles as an early pregnancy loss or missed abortion). In this case, the fertilized embryo implants in the uterus and the placenta and gestational sac begin to develop, but the resulting embryo either stops developing very early or doesn't form at all.

Because the placenta begins to secrete hormones, you'll get a positive pregnancy test and may have early pregnancy symptoms, but an ultrasound will show an empty gestational sac. In other cases, the embryo does develop for a little while but has abnormalities that make survival impossible, and development stops before the heart starts beating.

Risk factors for miscarriage

Though any woman can miscarry, some are more likely to miscarry than others. Here are some risk factors:

• Age: Older women are more likely to conceive a baby with a chromosomal abnormality and to miscarry as a result. In fact, 40-year-olds are about twice as likely to miscarry as 20-year-olds. Your risk of miscarriage also rises with each child you bear.
• A history of miscarriages: Women who have had two or more miscarriages in a row are more likely than other women to miscarry again.
• Chronic diseases or disorders: Poorly controlled diabetes, autoimmune disorders (such as antiphospholipid syndrome or lupus), and hormonal disorders (such as polycystic ovary syndrome) are some of the conditions that could increase the risk of miscarriage.
• Uterine or cervical problems: Having certain congenital uterine abnormalities, severe uterine adhesions (bands of scar tissue), or a weak or abnormally short cervix (known as cervical insufficiency) up the odds for a miscarriage. The link between uterine fibroids (a common, benign growth) and miscarriage is controversial, but most fibroids don't cause problems.
• A history of birth defects or genetic problems: If you, your partner, or family members have a genetic abnormality, have had one identified in a previous pregnancy, or have given birth to a child with a birth defect, you're at higher risk for miscarriage.
• Infections: Research has shown a somewhat higher risk for miscarriage if you have listeria, mumps, rubella, measles, cytomegalovirus, parvovirus, gonorrhea, HIV, and certain other infections.
• Smoking, drinking, and using drugs: Smoking, drinking alcohol, and using drugs like cocaine and MDMA (ecstasy) during pregnancy can all increase your risk for miscarriage. Some studies show that high levels of caffeine consumption are linked to an increased risk of miscarriage.
• Medications: Some medications have been linked to increased risk of miscarriage, so it's important to ask your caregiver about the safety of any medications you're taking, even while you're trying to conceive. This goes for prescription and over-the-counter drugs, including nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and aspirin.
• Environmental toxins: Environmental factors that might increase your risk include lead; arsenic; some chemicals, like formaldehyde, benzene, and ethylene oxide; and large doses of radiation or anesthetic gases.
• Paternal factors: Little is known about how the father's condition contributes to a couple's risk for miscarriage, though the risk does rise with the father's age. Researchers are studying the extent to which sperm could be damaged by environmental toxins but still manage to fertilize an egg. Some studies have found a greater risk of miscarriage when the father has been exposed to mercury, lead, and some industrial chemicals and pesticides.
• Obesity: Some studies show a link between obesity and miscarriage.
• Diagnostic procedures: There's a small increased risk of miscarriage after chorionic villus sampling and amniocentesis, which may be performed for diagnostic genetic testing.
• Short time between pregnancies: Your risk of miscarriage is higher if you get pregnant within three months after giving birth.

If you think you're having a miscarriage

Call your doctor or midwife immediately if you ever notice unusual symptoms such as bleeding or cramping during pregnancy. Your practitioner will examine you to see if the bleeding is coming from your cervix and check your uterus. They may also do a blood test to check for the pregnancy hormone hCG and repeat it in two to three days to see if your levels are rising as they should be.

If you're having bleeding or cramping and your practitioner has even the slightest suspicion that you have an ectopic pregnancy, you'll have an ultrasound right away. If there's no sign of a problem but you continue to spot, you'll have another ultrasound in a couple of weeks.

At this point, if the sonographer sees an embryo with a normal heartbeat, you have a viable pregnancy and your risk of miscarrying is now much lower, but you'll need to have another ultrasound later if you continue to bleed. If the sonographer determines that the embryo is the appropriate size but there's no heartbeat, it may mean that the embryo didn't form or didn't survive.

If you're in your second trimester and an ultrasound shows your cervix is shortening or opening, your doctor may decide to perform a procedure called cerclage, in which they stitch your cervix closed in an attempt to prevent miscarriage or premature delivery. (This is assuming your baby appears normal on the ultrasound and you have no signs of an intrauterine infection.) Cerclage isn't without risk, and you may not meet the criteria for it.

Your caregiver may suggest that you not have sex while you're having bleeding or cramping. Sex doesn't cause miscarriage, but it's a good idea to abstain while you're having these symptoms.

Treatment for miscarriage

If you're miscarrying, discuss the pros and cons of treatment options with your caregiver. If there's no threat to your health, you may choose to wait and let the tissue pass on its own. (More than half of women spontaneously miscarry within a week of finding out that the pregnancy is no longer viable.)

If you wait for the tissue to pass on its own, you may have light bleeding and cramping for a few weeks. You can wear sanitary pads but no tampons during this time and take acetaminophen for the pain. The bleeding and cramping will likely get worse shortly before you pass the "products of conception" – that is, the placenta and the embryonic or fetal tissue, which will look grayish and may include blood clots.

Or you may decide to have a surgical procedure to remove the tissue. This is done by suction dilation and curettage (D&C).

You'll definitely need to have the tissue removed right away if you have any problems that make it unsafe to wait, such as significant bleeding or signs of infection. And your practitioner may recommend the procedure if this is your second or third miscarriage in a row, so the tissue can be tested for a genetic cause.

If you choose to have suction dilation and curettage, the procedure doesn't usually require an overnight stay unless you have complications. As with any surgery, you'll need to arrive with an empty stomach – no food or drink since the night before.

The doctor will insert a speculum into your vagina, clean your cervix and vagina with an antiseptic solution, and dilate your cervix with narrow metal rods (unless your cervix is already dilated from having passed some tissue). In most cases, you'll be given sedation through an IV and a local anesthetic to numb your cervix.

Then the doctor will pass a hollow plastic tube through your cervix and suction out the tissue from your uterus. Finally, they'll use a spoon-shaped instrument called a curette to gently scrape any remaining tissue from the walls of your uterus. The whole procedure may take about 15 to 20 minutes, though the tissue removal itself takes less than ten minutes.

Finally, if your blood is Rh-negative, you'll receive a shot of Rh immune globulin unless the baby's father is Rh-negative, too.

What happens after a miscarriage

Whether you pass the tissue on your own or have it removed, you'll have mild menstrual-like cramps afterward for up to a day or so and light bleeding for a week or two. Use pads instead of tampons and take ibuprofen or acetaminophen for the cramps. Avoid sex, swimming, and using vaginal medications for at least a couple of weeks and until your bleeding has stopped.

If you begin to bleed heavily (soaking a sanitary pad in an hour), have any signs of infection (such as fever, achiness, or foul-smelling vaginal discharge), or feel excessive pain, call your practitioner immediately or go to the emergency room. If your bleeding is heavy and you begin to feel weak, dizzy, or lightheaded, you may be going into shock. In this case, call 911 right away – don't wait to hear from your caregiver, and don't drive yourself to the ER.

The chance of having another miscarriage

It's understandable to be worried about the possibility of another miscarriage, but fertility experts don't consider a single early pregnancy loss to be a sign that there's anything wrong with you or your partner.

Some practitioners will order special blood and genetic tests to try to find out what's going on after two miscarriages in a row, particularly if you're 35 or older or you have certain medical conditions. Others will wait until you've had three consecutive losses. In certain situations, such as if you had a second-trimester miscarriage or an early-third-trimester premature birth from a weakened cervix, you might be referred to a high-risk specialist after a single loss so your pregnancy can be carefully managed.

Conceiving again after a miscarriage

You may have to wait a bit. Whether you miscarry spontaneously, with the help of medication, or have the tissue removed, you'll generally get your period again in four to six weeks.

You can start trying to conceive again after this period, but you may want to wait longer so that you have more time to recover physically and emotionally. (You'll need to use birth control to prevent conception during this time, because you may ovulate as early as two weeks after you miscarry.)

How to cope after a miscarriage

Though you may be physically ready to get pregnant again, you may not feel ready emotionally. Some women cope best by turning their attention toward trying for a new pregnancy as soon as possible. Others find that months or more go by before they're ready to try to conceive again. Take the time to examine your feelings, and do what feels right for you and your partner. For more information see our article on coping with pregnancy loss.

You may find help in a support group (your caregiver can refer you to one) or in our Community's Miscarriage, Stillbirth, and Infant Loss Support group.

If you're feeling overwhelmed by your sadness, call your caregiver. They can put you in touch with a therapist who can help.

If you're wondering how to explain a pregnancy loss to your child, read about how to talk to your preschooler about pregnancy loss.