Preterm labor and delivery can happen to any pregnant woman. But they happen more often to some women than to others. Researchers continue to study preterm labor and birth. They have identified some risk factors, but still cannot predict which women will give birth too early. Having a risk factor does not mean a woman will have preterm labor or preterm birth.

Three groups of women are at greatest risk of preterm labor and birth:

• Women who are pregnant with twins, triplets or more
• Women who have had a previous preterm birth
• Women with certain uterine or cervical abnormalities

If you have any of these three risk factors, it's especially important for you to know the signs and symptoms of preterm labor and what to do if they occur.

Researchers also have identified other risk factors. For instance, African-American women and women younger than 17 or older than 35 are at greater risk than other women. Experts do not fully understand why and how these factors increase the risk that a woman will have preterm labor or birth.

Lifestyle Risks for Preterm Labor
Some studies have found that certain lifestyle factors may put a woman at greater risk of preterm labor. These factors include:

• Late or no prenatal care
• Smoking
• Drinking alcohol
• Using illegal drugs
• Domestic violence, including physical, sexual or emotional abuse
• Lack of social support
• High levels of stress
• Long working hours with long periods of standing
• Low income

Medical Risk Factors for Preterm Labor
Certain medical conditions during pregnancy may increase the likelihood that a woman will have preterm labor. These conditions include:

• Premature rupture of the membranes (the sac inside the uterus that holds the baby breaks too soon)
• Urinary tract infections, vaginal infections, sexually transmitted infections and possibly other infections
• High blood pressure
• Diabetes
• Clotting disorders thrombophilia)
• Being underweight before pregnancy
• Obesity
• Short time period between pregnancies (less than 6-9 months between birth and the beginning of the next pregnancy)
• Certain birth defects in the baby
• Bleeding from the vagina

What Can Women Do for Preterm Labor?
Remember, though, even if you have one of these risk factors, it does not mean you will have preterm labor. It just means that you are at greater risk than a woman who does not have a risk factor. Still, knowing you're at risk is scary. That's why it's so important that you:

• Know the signs and symptoms of preterm labor
• Know what to do if you have any of them
• Take very good care of yourself and your baby while you're pregnant

This is the best way to protect yourself and your baby against preterm labor.

Content courtesy of March of Dimes.