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What Is Premature Labor?
If labor occurs before a pregnancy reaches its 37th completed week (full term is normally 40 weeks), it’s called premature labor, or preterm labor.
The World Health Organization defines preterm labor as the onset of contractions of the uterus before the 37th completed week of pregnancy that are:
- Palpable (that can be felt by a health professional)
If there is also progressive effacement (shortening) and dilation (opening) of the
Just as normal labor differs in intensity from one woman to another, so do the contractions of premature labor. Some women do not have painful contractions, but describe being “uncomfortable” or merely feeling “as if something isn’t right.” If you think you might be in preterm labor, trust your instincts and contact your health care provider for a complete exam.
The uterus is a muscle. During labor, it contracts, causing the cervix to shorten and open so that the baby can be born.
- As labor progresses, the contractions become more frequent, stronger, and more regular.
- Eventually the cervix opens fully, allowing delivery to take place.
- When contractions cause the cervix to begin to open prior to the 37th week of pregnancy, this is premature labor.
Nice To Know:
Facts About Premature Labor
Symptoms Of Premature Labor
The following signs of premature labor can also be a very normal part of pregnancy. Therefore, if you feel you are experiencing a symptom, try to determine whether this represents a change in the pattern of your pregnancy or whether it has been a normal occurrence for you.
- Uterine contractions – regular contractions, four or more per hour
- Cramps – often similar to menstrual cramps, sometimes rhythmic, either painful or painless
- Backache – low, dull back pain
- Pelvic Pressure – could be either rhythmic or persistent
- Intestinal cramps – like gas pains, with or without diarrhea
- Increase or change in vaginal secretions – increase in the amount of mucous, change in color to pink or brown, or a large amount of fluid.
If You Think You Are Experiencing Signs Of Premature Labor
It is a good idea to check for uterine contractions once a day during your pregnancy. To monitor contractions, do the following:
- Lie down on your left side (or relax in a comfortable position).
- Use your fingertips to press on your abdomen just below and to the sides of your belly button.
- Normally, your fingers will indent the uterine wall.
- If your uterus becomes tight and hard and cannot be indented with gentle fingertip pressure, you are having a contraction.
- Check the time, and determine how many minutes your uterus remains tight. This is the ‘length’ of the contraction.
- If another contraction occurs, determine how many minutes elapsed between the beginning of the first and the beginning of the second contraction (how ‘far apart’ they are).
- It is normal for the uterus to contract 0-3 times per hour.
Need To Know:
If you experience four or more contractions in an hour, contact your health care provider or go to the labor and delivery unit of your hospital for a check-up.
What Causes Premature Labor?
The mechanism that causes normal term labor to begin is not completely understood, so the actual cause of premature labor is also unknown. However, there are some factors that may increase a woman’s risk for premature labor.
Risk factors in a woman’s medical history that can lead to premature labor include:
- Infection in the
- A previous premature delivery
- Multiple pregnancy – twins, triplets, etc.
- Poor socio-economic status
- Previous miscarriages or terminations of pregnancies (especially if these were repeated and late)
- Premature rupture of membranes
- Previous surgery on the cervix (line conization)
- Exposure to diethylstilbestrol (DES), a synthetic estrogen commonly given to pregnant women between 1938 and 1971. DES is no longer used because of a link to birth defects.
Nice To Know:
While twins account for 1 in 80 of all pregnancies, they account for 1 in 10 preterm births. 50 percent of twin pregnancies deliver prematurely.
While it is normally desirable for a pregnancy to reach its full term, there are circumstances in which obstetricians must induce preterm delivery for the safety of the mother, the child, or both. One of the following may necessitate the induction of
- Severe hypertension or
eclampsia, or a seizure or coma in a woman with pre-eclampsia; a condition occurring during the second half of pregnancy characterized by high blood pressure, swelling, and large amounts of protein in the urine.
- If the amniotic sac ruptures prior to the 37th week of pregnancy, this is a condition known as preterm premature rupture of the membranes (PPROM). The decision to induce preterm labor will depend on the gestational age of the fetus and the presence of an infection.
- Fetal stress, where evidence of poor growth and lack of oxygen is discovered.
Normally, every effort is made to assure that a baby is as mature as possible prior to delivery. In some cases, however, even a very premature baby is better served by Neonatal Intensive Care Unit (NICU) facilities than by continued dependency on a less-than-healthy uterine environment.
In many cases, premature labor occurs without any known risk factors, making it very difficult to predict which women will deliver preterm.
Because of the difficulty in predicting premature labor risk, all pregnant women should be familiar with the signs and symptoms of preterm labor.
- Many measures designed to prevent premature labor have not been proven to work in well-designed scientific studies. These include complete bed rest, oral medications to stop contractions, machine monitoring of contractions at home and pump subcutaneous injections of
tocolyticmedications to stop contractions.
- In women with an abnormal or deformed cervix that opens prematurely (incompetent cervix), putting a stitch (cerclage) around the cervix to prevent it from opening is often done to prevent premature labor.
How Is Premature Labor Diagnosed?
Since it is difficult to predict or prevent premature labor, health care providers often have to cope with managing the condition as it arises.
Contractions alone aren’t enough to accurately diagnose premature labor. Diagnosis depends on detecting changes in the cervix by vaginal examination.
Final diagnosis depends on answering two questions:
- Is it really labor?
- Is it really premature?
When a woman feels that her uterus is contracting and she suspects that she is in
If labor has in fact begun and the doctor decides to attempt to halt the process, it is most easily accomplished before the situation has progressed too far. Therefore, a woman who suspects she is in labor should not ignore the symptoms.
Only your health care provider can accurately diagnose preterm labor. There are several ways to assess your condition:
- A vaginal exam to determine whether the cervix has begun to shorten (efface) and open (dilate) will be necessary to determine whether the contractions are causing labor.
- Measuring cervical length by
transvaginal ultrasoundearly in pregnancy is a good indicator of the possibility of preterm delivery.
- A swab of cervicovaginal secretions can be tested for the presence of
fetal fibronectin(a protein found in fetal membranes and amniotic fluid), which is associated with preterm delivery. A new rapid test has recently become available. If this test is negative, there is a very low risk of delivery in the next two weeks.
- The fact that babies cease having chest movements (fetal breathing) during labor has been employed to try to improve diagnosis. While not infallible, it is true, in general, that if fetal breathing can be seen on ultrasound scan, the woman is unlikely to progress to delivery; whereas if fetal breathing is absent, it is more likely that she is experiencing preterm labor.
Once your medical care provider has established that you are in labor, he or she must determine if the baby is actually premature before deciding to halt the process. If the date of your conception is well-established by accurate menstrual dates and/or early ultrasound examinations, this is an easy task.
However, if you are seeking medical care for the first time while having contractions, and the actual date of the last menstrual period is not known, you could actually be in normal full term labor with a very small baby. Tests of amniotic fluid contents obtained by amniocentesis will predict the maturity of the fetus.
Premature Labor – What To Expect
After diagnosis of premature labor has been made, careful consideration must be given as to whether or not labor should be stopped. This will depend on a number of factors:
- The mother’s condition will be assessed by checking her vital signs and possibly doing blood tests.
- The baby’s status will be determined by monitoring the heartbeat and possibly by ultrasound analysis to estimate size and function of various organs.
Labor might be allowed to continue for the following reasons:
- Most doctors will not try to stop labor if the mother is at 37 weeks gestation or beyond.
- If the membranes are ruptured and the pregnancy has reached 34 weeks gestation, many obstetricians will be reluctant to try to stop labor.
- If the mother or fetus demonstrates serious disease, this may be a reason not to attempt to stop labor.
If the decision is made to try to stop labor, several different methods can be used:
- Depending on the condition of you and your baby, and how far labor has progressed (how much the
cervixhas effaced and dilated), intravenous tocolyticdrug treatment for premature labor may be administered in the hospital.
- Often, labor can be stopped in the hospital using intravenous medications, and then you can return home with instructions for reduced activity.
You will be instructed as to the safest activity level for your situation. This might be total bed rest in the hospital, complete bed rest at home with bathroom privileges, or partial bed rest – essentially, staying off your feet as much as possible.
You will also be instructed to keep yourself well hydrated.
When the decision has been made that premature labor should be stopped, a number of medications can be used in an effort to stop contractions and to assure the infant will be as mature as possible at birth.
Tocolytics are medications that decrease uterine contractions. Tocolytic treatment is not uniformly successful and may cause serious side effects, so careful monitoring is necessary. Scientific studies show the ability of these drugs to prolong labor only by 48 hours.
- The most commonly used tocolytic is
magnesium sulfate, which is administered in the hospital through an intravenous drip.
Need To Know:
Women with known or suspected heart conditions should notify their physicians before administration of tocolytics.
Another group of tocolytics (ritodrine and terbutaline) can be used for
Other drugs, such as prostaglandin blockers (Indometacin) and calcium channel blockers (nifedipine) are also used.
The most important and successful medications to treat preterm labor patients are glucocorticoid steroids (Betametasane and Decadron). These are given over a 24-hour time period by injection, and they increase the maturity and function of immature fetal lungs. These steroids have been proven to reduce premature neonate problems of respiratory diseases, ventilator use, and brain hemorrhage.
Steroid injections are best given within a certain gestational age range, usually 24 to 34 weeks. In the past, multiple injections were given, but recent research indicates that more than one injection may not be beneficial and may even be harmful to the baby.
How Can I Prepare For A Preterm Delivery?
The birth of a fetus prior to 20 weeks is known as a miscarriage or spontaneous abortion, as survival is impossible at this point.
- Labor beginning between 20 and 37 weeks is “
- A baby born at 24 weeks gestation has about a 50 percent chance of survival.
- A baby born at 26 weeks gestation has about an 80 percent chance of survival.
- A baby born at 28 weeks gestation has about a 91 percent chance of survival.
- For a baby born after 28 weeks and weighing more than 3 pounds, the chances of survival are even further increased.
- After 32 weeks gestation, a baby has a 96 percent chance of survival and a significant decrease in the chances of suffering significant health problems. Babies born between the 34th and 36th week of pregnancy are likely to have minor developmental delays, but are not likely to experience any long-term effects.
In general terms, the earlier a baby is born and the lower the birth weight, the lower the chance of survival and the higher the chance of handicap. Preterm babies suffer from a host of problems associated with immaturity of some or all of their organs and systems.
- The natural mechanisms that combat infection are poorly developed, so preterm infants are particularly prone to developing infections.
- Their skin is very thin and underdeveloped, with very little subcutaneous fat (the fat under the skin), so they quickly lose heat and are difficult to keep warm.
- The lungs lack a substance called surfactant, which helps them expand. This causes difficulty in picking up sufficient oxygen from the atmosphere and removing carbon dioxide from the blood – a condition called respiratory distress syndrome.
- The stomach may not be sufficiently developed to accept milk immediately.
- The sucking reflex may not be present at birth.
- The liver is immature, so jaundice is common and may be dangerous if severe.
- Blood vessels supplying the brain may be particularly fragile and sensitive to damage, resulting in bleeding inside the skull. Depending on the degree of bleeding involved, this can have potentially serious long-term consequences, such as physical and mental handicaps and cerebral palsy.
Ideally, babies who are born preterm should be delivered in hospitals prepared to care for their special needs with neonatal intensive care nurseries. Obstetricians and pediatricians are often able to predict, before birth, whether a baby is likely to need intensive care facilities, and, if so, the mother can be transported to that facility before delivery.
Parents who are at risk for delivering a premature baby might benefit from a visit to the NICU and a discussion with the
Ideally, all normal preterm babies who are positioned with their heads down should be delivered vaginally by an experienced physician.
- There is no indication for the routine use of forceps, though an
episiotomy(an incision in the perineum, the area between the vagina and anus) may help to reduce the pressure on the delicate head of the preterm infant.
- If complications develop, it may be necessary to deliver immediately by Cesarean section to minimize harm to the baby.
- Most physicians deliver breech (bottom first) babies by Cesarean section.
Premature Labor: Frequently Asked Questions
Here are some frequently asked questions related to premature labor:
Q: I am feeling what might be contractions, but I hate to bother my doctor – what should I do?
A: Experiencing two or three contractions during an hour is normal for a healthy pregnancy. Contractions can be brought on by sexual intercourse, the baby changing position, a doctor’s exam, or dehydration. Try drinking a glass of water and resting for a while, then monitor yourself for contractions. If you still suspect premature labor, call your health care provider immediately.
Q: My vaginal discharge is different than it was a few days ago. Is this normal?
A: An increase in vaginal discharge might be a warning sign of
Q: I woke up with wet underpants, but it does not smell like urine. What is it?
A: You could be leaking amniotic fluid. Call your health care provider immediately.
Q: My doctor told me not to lie on my back while on bed rest. Why is that?
A: Lying flat on your back may cause the large blood vessels supplying blood and oxygen to you and your baby to be compressed.
Q: My doctor put me on bed rest last week and I am already going crazy. How will I survive the next two months? What can I do?
A: You are doing your first big job as a parent by trying to keep your baby inside your uterus until he is mature enough to breathe and eat on his own. Enlist support from friends and family, and talk to someone who has been on bed rest and who can remind you of the enormous gift you are giving your baby.
Premature Labor: Putting It All Together
Here is a summary of the important facts and information related to premature labor:
- Premature labor, or
preterm labor, is defined as the onset of labor before the 37th full week of pregnancy.
- If your baby is born early, but after 28 weeks of gestation, it is likely that he will be mature enough to survive. However, the longer your baby stays inside your uterus, the more prepared he will be to breathe and eat on his own.
- Early and accurate detection and diagnosis of premature labor is critical, because premature labor is easier to control when labor has not progressed too far.
- If you experience any of the symptoms of premature labor, consult your health care provider immediately. Only he or she help you determine for sure whether you are in labor.
- Avoid an emergency home, car, or ambulance delivery by familiarizing yourself with the signs of premature labor and contacting your health care provider immediately with any questions you might have.
- Because premature labor risk is difficult to predict, ALL pregnant women should be familiar with its signs and symptoms.
Premature Labor: Glossary
Here are definitions of medical terms related to premature labor:
Braxton Hicks Contractions: Normal contractions of the uterus, usually painless, in which it tightens and becomes hard.
Cesarean Section: A surgical method of delivering a baby through an abdominal incision in the uterus.
Cerclage: A stitch put around the cervix to help prevent preterm delivery.
Cervix: The lower part of the uterus, often referred to as the neck of the uterus.
Diethylstilbestrol (DES): A synthetic estrogen given to millions of pregnant women between 1938 and 1971 because it was thought to prevent miscarriages. It is no longer used for that purpose.
Eclampsia: A severe form of pre-eclampsia, resulting in coma or seizures.
Episiotomy: A surgical incision in the perineum (the muscular areas between the vagina and anus) used to facilitate delivery.
Fetal Fibronectin: A protein found in fetal membranes and amniotic fluid.
Intrauterine Growth Retardation: A condition in which the fetus weighs less than 10 percent of what it should for its gestational age.
Neonatal intensive care unit (NICU): A specialized unit of the hospital equipped to treat preterm infants.
Neonatologist: A specialist trained in treating and caring for preterm infants.
Pre-eclampsia: Also called toxemia; an illness that occurs during late pregnancy characterized by high blood pressure, swelling of the hands, feet and face, and large amounts of protein in the urine.
Premature labor: Also preterm labor; labor occurring before 37 full weeks of pregnancy.
Preterm Labor: Also premature labor; labor occurring before 37 full weeks of pregnancy.
Preterm Premature Rupture of the Membranes (PPROM): When the amniotic sac ruptures prior to the 37th week of pregnancy.
Protaglandin: A hormone-like substance that causes uterine contractions.
Terbutaline: Also known as Breathine; a tocolytic medication that can be used to relax the uterus and reduce contractions.
Tocolytic: Medication that relaxes the uterus to reduce contractions.
Magnesium sulfate: A tocolytic medication used to relax the uterus and reduce contractions.
Transvaginal ultrasound: A method of imaging the pelvic region in which an ultrasound probe is inserted into the vagina.
Premature Labor: Additional Sources Of Information
Here are some reliable sources that can provide more information on premature labor:
Sidelines National Support Network
Resources for Parents of Preemies
Twinslist.org (Resources for parents of multiples)
American College of Obstetricians and Gynecologists
Cord Blood Banking Information
Provides information on public and private umbilical cord blood collection and storage.