Pregnancy loss occurs when a pregnancy ends prematurely. It's a sad fact that miscarriages are quite common. Although the precise number of pregnancies that end in miscarriage is not known, it is estimated at about 20%.

The highest risk for pregnancy loss is in the first trimester -- often a woman might not have even realized she was pregnant. For others, an early pregnancy loss is devastating. When a woman loses a baby later in the pregnancy, between the 14th and 24th weeks, it's referred to as a second trimester loss or late miscarriage.

The good news is that in most cases, a woman who has lost a pregnancy will later carry a healthy baby to full term.

What Are the Causes of Miscarriage?

Although a doctor or midwife may not be able to provide a conclusive answer, there are several possibilities.

• In many cases an early pregnancy loss occurs because of a chromosomal abnormality.
• Second trimester miscarriages can occur due to a uterine or placental abnormality or infection. In the case of a “weak” cervix, in future pregnancies the cervix can be strengthened with a stitch.
• Some miscarriages are caused by an infection (for example, chlamydia, rubella, or listeria).

What Are Common Miscarriage Symptoms?

The signs of miscarriage include:

• Lower back pain, cramping, and spotting followed by heavier bleeding
• Heavier bleeding with clots or tissue
• Pregnancy symptoms like breast tenderness and morning symptoms fade

The Five Types of Miscarriages

• Missed: In some cases the pregnancy doesn't develop and it isn't until an ultrasound appointment that the woman realizes the pregnancy was lost. A blighted ovum occurs when the sac develops but for some reason the fetus doesn't.
• Inevitable: If a woman's cervix is open (for example, a “weak” or “incompetent” cervix), a pregnancy loss is imminent. Fortunately in the case of weak cervix, the issue can be rectified for a future pregnancy.
• Incomplete: In this case, the pregnancy has ended and bleeding has occurred but there is tissue left in the uterus. In some cases medical intervention (a D&C) is needed to remove the tissue.
• Complete: A complete miscarriage refers to a pregnancy loss that has run its course: the bleeding has stopped, the cervix is closed, and the uterus is empty.
• Threatened: When bleeding occurs, it is not necessarily a bad sign, but pregnancy loss is a possibility. Consult your doctor who will take steps to confirm whether the pregnancy is still viable (an ultrasound to check the heartbeat as well as ensuring that the cervix is closed).

What Treatment Is Available?

For many women, seeking medical attention isn't necessary as bleeding resolves on its own within a few weeks. If you are experiencing pain and continued discomfort, or fear an incomplete miscarriage, your medical professional may provide a prescription for pain relief or to help things proceed. In some cases, surgery may be recommended to remove any remaining tissue.

If you believe you may have had a miscarriage, your doctor can request an ultrasound or run blood tests -- or you can take home pregnancy tests several days apart to compare hormone levels.

Can Pregnancy Loss Be Prevented?

Pregnancy loss can be devastating to women. Although there isn't anything you can do to stop it from occurring, you can take steps to improve your health so you reduce the risk. If you are older than 35, avoid unhealthy habits like excessive caffeine consumption, drinking alcohol, smoking, or drug use. Obesity can also be a risk factor -- another good reason to ensure you're at your healthiest before conceiving, or at least prepared to take steps to improve your health during pregnancy.