Preterm Labor and Birth

A typical pregnancy lasts about 40 weeks. Preterm labor is labor that starts before 37 weeks of pregnancy. Going into preterm labor does not automatically mean that you will have a preterm birth. But preterm labor needs medical attention right away.

Preterm birth is the birth of a baby before 37 weeks. Preterm babies may be born with serious health problems. Some health problems, like cerebral palsy, can be lifelong. Other problems, such as learning disabilities, may appear later in childhood or even in adulthood.

In some cases, yes. For about 3 in 10 women, preterm labor stops on its own. If it does not stop, treatments may be given to try to delay birth. In some cases, these treatments may reduce the risk of complications if the baby is born.

Preterm labor contractions lead to changes in the cervix. The changes include effacement (thinning of the cervix) and dilation (opening of the cervix). Signs and symptoms include the following:

• Mild abdominal cramps, with or without diarrhea

• A change in type of vaginal discharge—watery, bloody, or with mucus

• An increase in the amount of discharge

• Pelvic or lower abdominal pressure

• Constant, low, dull backache

• Regular or frequent contractions or uterine tightening, often painless

• Ruptured membranes (your water breaks with a gush or a trickle of fluid)

If you have any signs or symptoms of preterm labor, do not wait. Call the office of your obstetrician–gynecologist (ob-gyn) right away or go to the hospital.

Preterm labor can happen to anyone without warning. But there are some factors that can increase the risk of preterm labor, including:

• preterm birth in a past pregnancy

• having a short cervix early in pregnancy

• past gynecologic conditions or surgeries

• current pregnancy complications

• lifestyle factors (read “What are the risk factors for preterm birth” below)

Many women who have preterm births have no known risk factors. Some risk factors include the following:

Medical History

• Past preterm birth

• Short cervix (measured during a transvaginal ultrasound exam)

• Early cervical dilation (measured during a pelvic exam)

• Past procedures on the cervix

• Injury during a past delivery

Pregnancy Complications

• Carrying more than one fetus

• Vaginal bleeding during pregnancy

• Infections during pregnancy

Lifestyle Factors

• Low prepregnancy weight

• Smoking during pregnancy

• Dietary deficiencies

Other Factors

• Younger than 17 or older than 35

Preterm labor is diagnosed when changes in the cervix are found after contractions start. Your ob-gyn may do a pelvic exam to see if your cervix has started to change. You may need to be examined several times over a period of a few hours. Your contractions may also be monitored.

There are several tests that may be ordered:

• An ultrasound exam to estimate gestational age or to check the size of your fetus.

• A transvaginal ultrasound exam to measure the length of the cervix.

• A vaginal swab to test for the presence of fetal fibronectin. This is a protein that acts like a glue, helping the amniotic sac stay connected to the inside of the uterus.

If you have preterm labor, it is difficult for health care professionals to predict whether you will go on to have preterm birth. The goals of monitoring and treatment are to reduce the risk of preterm birth and protect the health of you and your fetus.

Preterm labor should be managed based on what is best for your health and the fetus's health. If the fetus would benefit from a delay in delivery, medications may be given to

• help the organs mature more quickly

• reduce the risk of certain complications

• attempt to delay delivery for a short time

When preterm labor is too far along to be stopped, delivery may be necessary. If your hospital does not have the resources to care for preterm babies, your ob-gyn may recommend transfer to another hospital with these resources.

Medications that help prepare a fetus for preterm birth include corticosteroids, magnesium sulfate, and tocolytics.

Corticosteroids can help speed up development of the fetus’s lungs, brain, and digestive organs.

Corticosteroids may be recommended between 24 and 34 weeks of pregnancy for anyone at risk of delivery within 7 days, including those with ruptured membranes and those carrying more than one fetus.

In some cases, corticosteroids may be offered up to 36 weeks and 6 days of pregnancy. Corticosteroids may also be considered as early as 22 weeks of pregnancy after discussing the risks, benefits, and other possible options.

If you are likely to give birth within 1 week, a single course of corticosteroids is given. It takes 2 days after the first dose is given for the most benefits to occur, but there is some benefit in the first 24 hours.

A repeat course of corticosteroids can be given if a previous course was given more than 14 days ago, and there is risk for delivery within 7 days.

When given before preterm birth, magnesium sulfate may reduce the risk of cerebral palsy and problems with physical movement.

This medication may be given if you are less than 32 weeks pregnant and at risk of delivery within the next 24 hours. Magnesium sulfate may cause minor side effects, including flushing, hot flashes, blurred vision, and weakness.

Tocolytics are medications used to delay delivery, sometimes for up to 48 hours. If delivery is delayed even a few hours, it may allow more time to give corticosteroids or magnesium sulfate. This delay also may allow time for transfer to a hospital with specialized care for preterm babies.

Tocolytics are given when the benefits of the treatment outweigh the risks. Tocolytics typically are not given when

• there are preterm labor symptoms but no changes in the cervix

• it is thought that delivery would be better for you or your baby

• preterm labor has stopped

You may have side effects from tocolytics, some of which can be serious. The side effects differ depending on the medication.

If labor does not stop and you give birth early, a team of health care professionals takes care of the baby. The team may include a neonatologist.

The care a baby needs depends on how early the baby is born. A neonatal intensive care unit (NICU) provides specialized care for preterm babies. Some babies need to stay in the NICU for weeks or even months.

A significant risk factor for preterm birth is a past preterm birth. Women with past preterm birth are 2 to 3 times more likely to deliver preterm in the future. This risk increases with each preterm birth. But some women deliver preterm without any clear risk factors.

If you are at risk of preterm birth, talk with your ob-gyn about treatments that may help prevent it. Treatments may include:

• Vaginal progesterone—This treatment may be given if you have a short cervix diagnosed by ultrasound before 24 weeks of pregnancy. Vaginal progesterone is a gel or suppository that you place in your vagina every day until 37 weeks, unless delivery happens sooner.

• Cerclage—If you have a short cervix and have had a preterm birth before, a procedure called cerclage also may be done. In cerclage, the cervix is closed with one or more stitches.

Progesterone shots are no longer recommended for preventing preterm birth. This is because studies have shown the shots may not be effective for everyone who uses them. Learn more about progesterone shots and preterm birth.

No, bed rest is not recommended if you are at risk of preterm birth. Bed rest can increase the risk of blood clots, bone weakening, and loss of muscle strength.

Cerclage: A procedure in which the cervical opening is closed with stitches to prevent or delay preterm birth.

Cerebral Palsy: A disorder of the nervous system that affects movement, posture, and coordination. This disorder is present at birth.

Cervix: The lower, narrow end of the uterus at the top of the vagina.

Complications: Diseases or conditions that happen as a result of another disease or condition. An example is pneumonia that occurs as a result of the flu. A complication also can occur as a result of a condition, such as pregnancy. An example of a pregnancy complication is preterm labor.

Corticosteroids: Drugs given for arthritis or other medical conditions. These drugs also are given to help fetal lungs mature before birth.

Dilation: Widening the opening of the cervix.

Effacement: Thinning out of the cervix.

Fetal Fibronectin: A protein that is produced by fetal cells. It helps the amniotic sac stay connected to the lining of the uterus.

Fetus: The stage of human development beyond 8 completed weeks after fertilization.

Gestational Age: How far along a woman is in her pregnancy, usually reported in weeks and days.

Hormone: A substance made in the body that controls the function of cells or organs.

Magnesium Sulfate: A drug that may help prevent cerebral palsy when it is given to women in preterm labor who may deliver before 32 weeks of pregnancy.

Neonatal Intensive Care Unit (NICU): A special part of a hospital in which sick newborns receive medical care.

Neonatologist: A doctor who specializes in the diagnosis and treatment of disorders that affect newborn infants.

Obstetrician–Gynecologist (Ob-Gyn): A doctor with special training and education in women’s health.

Pelvic Exam: A physical examination of a woman’s pelvic organs.

Prepregnancy: Before pregnancy.

Preterm: Less than 37 weeks of pregnancy.

Progesterone: A female hormone that is made in the ovaries and prepares the lining of the uterus for pregnancy.

Tocolytics: Drugs used to slow contractions of the uterus.

Transvaginal Ultrasound Exam: A type of ultrasound in which the device is placed in your vagina.

Ultrasound Exam: A test in which sound waves are used to examine inner parts of the body. During pregnancy, ultrasound can be used to check the fetus.

Uterus: A muscular organ in the female pelvis. During pregnancy, this organ holds and nourishes the fetus.