Understanding miscarriage

Miscarriage is a relatively common experience — but that doesn't make it any easier. Ending a pregnancy without a baby to hold in your arms is heartbreaking. Take a step toward emotional healing by understanding what can cause a miscarriage, what increases the risk and what medical care might be needed.

What causes miscarriage?

Most miscarriages occur because the fetus isn't developing normally. Problems with the baby's genes or chromosomes are typically the result of errors that occur by chance as the embryo divides and grows — not problems inherited from the parents.

In a few cases, a mother's health condition — such as uncontrolled diabetes, thyroid disease, infections, blood-clotting problems, or problems with the uterus or cervix — may lead to miscarriage.

Routine activities — such as exercising, having sex, working or lifting heavy objects — can't provoke a miscarriage. Nausea and vomiting in early pregnancy, even if it's severe, won't cause a miscarriage. And a fall or other injury is unlikely to cause a miscarriage, unless the injury is serious enough to threaten your own life.

What increases the risk of miscarriage?

Various circumstances increase the risk of miscarriage, including:

• Age. Women older than age 35 have a higher risk of miscarriage than do younger women. Paternal age also may play a role. In a 2006 study, women whose partners were age 40 or older had a higher risk of miscarriage than did women whose partners were younger than age 25.
• Previous miscarriages. The risk of miscarriage is higher in women with a history of two or more previous miscarriages. After one miscarriage, your risk of miscarriage is the same as that of a woman who's never had a miscarriage.
• Chronic conditions. Women with certain chronic conditions, such as diabetes or thyroid disease, have a higher risk of miscarriage.
• Uterine or cervical problems. Certain uterine abnormalities or a weak or unusually short cervix may increase the risk of miscarriage.
• Smoking, alcohol and illicit drugs. Women who smoke or drink alcohol during pregnancy have a greater risk of miscarriage than do nonsmokers and women who avoid alcohol during pregnancy. Illicit drug use also increases the risk of miscarriage.
• Caffeine. The evidence linking caffeine consumption and miscarriage is inconclusive. Because of the unknowns, your doctor may recommend avoiding caffeine during the first trimester and limiting the amount of caffeine you drink to less than 300 milligrams a day during the second and third trimesters.
• Invasive prenatal tests. Some prenatal genetic tests, such as chorionic villus sampling and amniocentesis, carry a slight risk of miscarriage.

How is miscarriage diagnosed?

If you have signs or symptoms of miscarriage — such as vaginal bleeding or pain or cramping in your abdomen or lower back — consult your doctor promptly. He or she may do a pelvic exam to see if your cervix has begun to dilate. The doctor may use ultrasound to check for a fetal heartbeat and determine if the embryo is developing normally. You might need blood or urine tests as well.

If you're bleeding but your cervix hasn't begun to dilate, you're having a threatened miscarriage. Such pregnancies often proceed without any further problems. If you're bleeding, your uterus is contracting and your cervix is dilated, the miscarriage can't be stopped. This is known as an inevitable miscarriage.

When is it safe to try again?

It's possible to become pregnant during the menstrual cycle immediately after a miscarriage. But if you and your partner decide to attempt another pregnancy, make sure you're physically and emotionally ready. Your doctor may recommend waiting at least one menstrual cycle, if not longer.

If you experience multiple miscarriages, consider testing to identify any underlying causes — such as uterine abnormalities, immune system problems or hormone imbalances. If the cause of your miscarriages can't be identified, don't lose hope. Even without treatment, the ACOG reports that about 60 percent to 70 percent of women with repeated miscarriages go on to have successful pregnancies.

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