What is preterm labor?

Preterm birth can result in problems of the lungs, heart, brain, and other body systems of a newborn baby. Recent advances in the study of preterm labor have identified effective drugs that may delay delivery. The longer a baby can develop in the womb, the less likely they will have problems associated with preterm birth.

If you’re having signs of premature labor, call a doctor immediately. Symptoms of preterm labor include:

  • frequent or consistent contractions (tightening in the belly)
  • low back pain that is dull and constant
  • pressure in the pelvis or lower abdominal area
  • mild cramps in the abdomen
  • water breaking (watery vaginal discharge in a trickle or a gush)
  • a change in vaginal discharge
  • spotting or bleeding from the vagina
  • diarrhea

If you’re less than 37 weeks pregnant when you experience these symptoms, your doctor may try to prevent delivery by offering certain medications. In addition to giving tocolytic medicines to prevent contractions, your doctor may prescribe steroids to improve the baby’s lung function. If your water has broken, you may also be given antibiotics to prevent infection and help you stay pregnant longer.

Benefits and risks of corticosteroids

Some women go into labor very early. If you deliver before 34 weeks, receiving corticosteroid injections can improve your baby’s chances of doing well. These help the baby’s lungs to function.

Steroids are usually injected into one of the mother’s large muscles (arms, legs, or buttocks). The injections are given two to four times over a two-day period, depending on which steroid is used. The most common steroid, betamethasone (Celestone), is given in two doses, 12 mg each, 12 or 24 hours apart. The medications are most effective from two to seven days after the first dose.

Corticosteroids aren’t the same as the bodybuilding steroids used by athletes. Multiple studies have shown that prenatal corticosteroids are safe for mothers and babies.

What are the benefits of steroids?

Steroid treatment reduces the risk of lung problems for babies who are born early, particularly for those born between 29 and 34 weeks of pregnancy. Babies born more than 48 hours, but less than seven days, from the first dose of steroids appear to receive the greatest benefit.

This steroid treatment cuts the risk of lung disease in half and reduces a premature baby’s risk of dying by up to 40 percent. All babies born at less than 28 weeks had lung problems, but the problems were milder for those who got steroids before birth.

Steroids may also reduce other complications in babies. Studies have shown that some babies have fewer problems with their intestines and with bleeding in the brain when their mothers received a course of betamethasone prior to birth.

If you’re admitted to a hospital in preterm labor or you have a medical problem that your doctors worry will require an early delivery, you’ll probably be offered a course of steroids. Staying pregnant for those first two days after a corticosteroid shot is the first major milestone for you and your baby (or babies).

What are the risks of taking steroids?

Animal studies have shown that giving steroids to a pregnant female can affect the immune system, neurological development, and growth of her offspring. However, these effects have shown up only in studies where steroids were given in very high doses or early in the pregnancy. In the treatment of preterm labor, steroids are given later in pregnancy.

Human studies have not shown any significant risks associated with a single course of steroids. Older studies followed infants whose mothers were given steroids during pregnancy until the children were 12 years old. These studies showed no adverse effects from the steroids on the child’s physical growth or development. Still, more studies need to be done.

In the past, women at risk for preterm delivery received steroids once a week until they delivered. Data from infants and animal studies showed that multiple courses of steroids were linked to babies with lower birth weights and smaller heads. Currently, repeated courses aren’t recommended, unless you’re participating in a research study.

Who should take steroids?

In 1994, the National Institutes of Health (NIH) published guidelines on the administration of steroids to women with preterm labor. According to these guidelines, doctors should consider giving steroids to all women who:

  • are at risk for preterm delivery between 24 and 34 weeks of pregnancy
  • receive medications to help stop labor (tocolytic medications)

Who shouldn’t take steroids?

Steroids may make diabetes (both long-standing and pregnancy-related) more difficult to control. When given in combination with a beta-mimetic drug (terbutaline, brand name Brethine), they can be even more problematic. Women with diabetes will require careful blood sugar monitoring for three to four days after receiving steroids.

In addition, women with active or suspected infection in the womb (chorioamnionitis) shouldn’t receive steroids.

Benefits and risks of progesterone hormones: 17-OHPC

Some women are more likely than others to go into labor early. Women at high risk of a preterm delivery include those who:

  • have already given birth to a preterm baby
  • are carrying more than one baby (twins, triplets, etc.)
  • got pregnant shortly after a previous pregnancy
  • use tobacco, alcohol, or illicit drugs
  • conceived through in vitro fertilization
  • have had more than one miscarriage or abortion
  • have other health problems (such as an infection, weight concerns, anatomical abnormalities in the uterus or cervix, or certain chronic conditions)
  • have nutritional deficiencies
  • experience a very stressful or traumatic event during pregnancy (physical or emotional)
  • are African-American

Despite these known risks, many women who experience symptoms of preterm labor have no clear risk factors.

If you’ve had a preterm birth in the past, your obstetrician may recommend you get a progesterone shot or pessary (vaginal suppository). The most common form of progesterone hormone administered to prevent preterm birth is the 17-OHPC shot, or 17-alphahydroxyprogesterone caproate.

The 17-OHPC shot is a synthetic progesterone that is often administered prior to the 21st week of gestation. It’s intended to prolong pregnancy. The hormone works by keeping the uterus from contracting. The shot is typically given into the muscles of the woman receiving treatment on a weekly basis.

If progesterone is given as a pessary, it’s inserted into the woman’s vagina.

A prescription is required for this hormone treatment, and both the shots and the suppositories should be administered by a doctor.

What are the benefits of progesterone shots?

A review of clinical studies of 17-OHPC has demonstrated its ability to prolong pregnancy. Women who are at risk of delivering a baby before 37 weeks may be able to stay pregnant longer if they receive 17-OHPC prior to the completion of 21 weeks of pregnancy.

Other studies have demonstrated that if preterm birth does occur, babies who survive have fewer complications if their mothers received 17-OHPC before the birth.

What are the risks of progesterone shots?

As with any shot and hormone administration, 17-OHPC shots may cause some side effects. The most common include:

  • pain or swelling in the skin at the injection site
  • a skin reaction at the injection site
  • nausea
  • vomiting

Some experience other side effects such as:

  • mood swings
  • headaches
  • abdominal pain or bloating
  • diarrhea
  • constipation
  • changes in sexual drive or comfort
  • dizziness
  • allergy
  • flu-like symptoms

Women who receive the pessary are more likely to have unpleasant discharge or irritation in their vagina.

There is no indication that 17-OHPC shots have any negative effect on miscarriage, stillbirth, preterm birth, or birth defect risk. There isn’t enough known about the long-term effects on mothers or babies to recommend shots for women with other predisposing factors for preterm birth.

Although 17-OHPC shots may reduce the risk of preterm birth and some of its complications, it doesn’t appear to reduce the risk of infant death.

Who should get 17-OHPC shots?

Women who’ve previously experienced preterm labor are often offered a hormone shot called 17-OHPC. The American College of Obstetricians and Gynecologists (ACOG) recommends that only women with a history of labor prior to 37 weeks’ gestation receive a 17-OHPC shot. Women who have a history of premature delivery should take this drug.

Who shouldn’t get 17-OHPC shots?

Women without a prior preterm birth shouldn’t receive 17-OHPC shots until more research confirms their safety and effectiveness for other risk factors. In addition, women with allergies or serious reactions to the shot may wish to discontinue their use.

As well, there are some situations in which a longer pregnancy may be harmful to the mother or the fetus. Preeclampsia, amnionitis, and lethal fetal anomalies (or imminent fetal death) may make a prolonged pregnancy dangerous or fruitless. Always consult carefully with a health professional before deciding to receive 17-OHPC shots or suppositories.

Benefits and risks of tocolytics

Tocolytic medications are used to delay delivery. A variety of drugs have similar effects for delaying delivery 48 hours or more when a woman is experiencing preterm labor. Tocolytic drugs include the following medications:

  • terbutaline (although it’s no longer considered safe for injection)
  • ritodrine (Yutopar)
  • magnesium sulfate
  • calcium channel blockers
  • indomethacin (Indocin)

Tocolytics are prescription drugs that should only be administered between weeks 20 and 37 of pregnancy if symptoms of preterm labor exist. They shouldn’t be combined except under the close supervision of a doctor. Combining tocolytics can cause problems for both the mother and the baby.

In general, tocolytic drugs only delay delivery. They don’t prevent complications of preterm birth, fetal death, or maternal problems associated with preterm labor. They’re often given with prenatal corticosteroids.

What are the benefits of tocolytics?

All tocolytics, but prostaglandin inhibitors in particular, are effective at delaying delivery between 48 hours and seven days. This allows corticosteroids time to speed fetal development.

Tocolytics themselves don’t decrease the chances of death or illness for the newborn. Instead, they merely give extra time for the baby to develop or for other drugs to work.

Tocolytics may also delay delivery long enough for a woman to be transported to a facility with a neonatal intensive care unit if preterm birth or complications are likely.

What are the risks of tocolytics?

Tocolytics have a variety of side effects that range from very mild to very serious.

Common side effects include:

  • dizziness
  • headaches
  • lethargy
  • flushing
  • nausea
  • weakness

More serious side effects can include:

Because certain tocolytic drugs carry different risks, the specific drug chosen should depend on the woman’s health and personal risks.

There is some controversy over whether tocolytics themselves can cause problems at birth, such as breathing problems for the baby or infection in the mother.

Who should get tocolytics?

Women experiencing the symptoms of preterm labor, particularly before 32 weeks’ gestation, should receive tocolytic drugs.

Who shouldn’t get tocolytics?

According to ACOG, women shouldn’t get tocolytic drugs if they’ve experienced any of the following:

  • severe preeclampsia
  • placental abruption
  • infection of the uterus
  • lethal fetal abnormalities
  • signs of imminent fetal death or delivery

In addition, each type of tocolytic drug has risks for women with certain conditions. For example, women with diabetes or thyroid problems shouldn’t receive ritodrine, and women with serious liver or kidney problems shouldn’t receive prostaglandin synthetase inhibitors.

A doctor should have a thorough understanding of the woman’s particular health problems before prescribing a specific tocolytic drug.

Benefits and risks of antibiotics

Antibiotics are routinely given to women in preterm labor when the bag of water surrounding the fetus has broken. This is because ruptured membranes put a woman and her baby at greater risk for infection.

In addition, antibiotics are frequently used to treat infections such as chorioamnionitis and group B streptococcus (GBS) during preterm labor. Antibiotics require a prescription and are available in pill form or intravenous solution.

What are the benefits of antibiotics?

Many large, well-designed studies have shown that antibiotics reduce risks to mothers and babies and prolong pregnancy after a woman’s water breaks early. Some studies have shown that antibiotics may reduce problems in the newborn.

It’s possible that antibiotics may delay or prevent preterm birth by treating conditions (such as infections) that can cause preterm birth. On the other hand, it’s unclear whether antibiotics can delay delivery for women who are in preterm labor but haven’t broken their water. For now, using antibiotics to help treat all preterm labor remains controversial.

There is also data showing that antibiotics are helpful during preterm labor for women who carry the GBS bacteria. About one in five women will carry GBS, and babies who get infected during labor and delivery can become very sick. Antibiotics can treat GBS and reduce complications of a subsequent infection in the newborn, but carry risks for the mother.

Most healthcare providers test women for the bacteria about a month before their due date. The test involves taking swab samples from the lower vagina and rectum. Because it can take two or three days for test results to be returned, the general practice is to begin treating a woman for GBS before confirmation of infection if a woman is in preterm labor. Most doctors think that this practice is justified because as many as one in four women test positive for GBS.

Ampicillin and penicillin are the antibiotics most commonly used for treatment.

What are the risks of antibiotics?

The primary risk of antibiotics during preterm labor is an allergic reaction from the mother. In addition, some babies may be born with an infection that has resistance to antibiotics, making treatment of postpartum infections in those babies more difficult.

Who should get antibiotics?

According to ACOG, only women with signs of infection or a ruptured membrane (early water break) should receive antibiotics during premature labor. It isn’t currently recommended for routine use in women without either of these problems.

Who shouldn’t get antibiotics?

Women without signs of infection and with intact membranes should likely not receive antibiotics during preterm labor.

In addition, some women may have allergic reactions to particular antibiotics. A woman with known allergies to antibiotics should receive alternative antibiotics or none at all, following the recommendations of health professionals familiar with the mother’s risks.