premature labor


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Premature Labor

 

Definition

Premature labor is the term to describe contractions of the uterus that begin at weeks 20-36 of a pregnancy.

Description

The usual length of a human pregnancy is 38-42 weeks after the first day of the last menstrual period. Labor is a natural series of events that indicate that the birth process is starting. Premature labor is defined as contractions that occur after 20 weeks and before 37 weeks during the term of pregnancy. The baby is more likely to survive and be healthy if it remains in the uterus for the full term of the pregnancy. It is estimated that around 10% of births in the United States occur during the premature period. Premature birth is the greatest cause of newborn illness and death. In the United States, prematurity has a greater impact on African-Americans.

Causes and symptoms

The causes of premature labor cannot always be determined. Some research suggests that infection of the urinary or reproductive tract may stimulate premature labor and premature births. Multiple pregnancies (twins, triplets, etc.) are more likely to result in to premature labor. Smoking, alcohol use, drug abuse, and poor nutrition can increase the risk of premature labor and birth. Adolescent mothers are also at higher risk for premature delivery. Women whose mothers took diethylstilbestrol (DES) when they carried them are more likely to deliver prematurely, as are women who have had previous surgery on the cervix.
The symptoms of premature labor can include contractions of the uterus or tightening of the abdomen, which occurs every ten minutes or more frequently. These contractions usually increase in frequency, duration, and intensity, and may or may not be painful. Other symptoms associated with premature labor can include menstrual-like cramps, abdominal cramping with or without diarrhea, pressure or pain in the pelvic region, low backache, or a change in the color or amount of vaginal discharge. As labor progresses, the cervix or opening of the uterus will open (dilate) and the tissue around it will become thinner (efface). Premature rupture of membranes (when the water breaks) may also occur.
An occasional contraction can occur anytime during the pregnancy and does not necessarily indicate that labor is starting. Premature contractions are sometimes confused with Braxton Hicks contractions, which can occur throughout the pregnancy. Braxton Hicks contractions do not cause the cervix to open or efface, and are considered "false labor."

Diagnosis

The health care provider will conduct a physical examination and ask about the timing and intensity of the contractions. A vaginal examination is the only way to determine if the cervix has started to dilate or efface. Urine and blood samples may be collected to screen for infection. A vaginal culture (a cotton-tipped swab is used to collect some fluid and cells from the vagina) may be done to look for a vaginal infection. A fetal heart monitor may be placed on the mother's abdomen to record the heartbeat of the fetus and to time the contractions. A fetal ultrasound may be performed to determine the age and weight of the fetus, the condition of the placenta, and to see if there is more than one fetus present. Amniocentesis will sometimes be performed. This is a procedure where a needle-like tube is inserted through the mother's abdomen to draw out some of the fluid surrounding the fetus. Analysis of the amniotic fluid can determine if the baby's lungs are mature. A baby with mature lungs is much more likely to survive outside the uterus.

Key terms

Braxton Hicks contractions — Tightening of the uterus or abdomen that can occur throughout pregnancy. These contractions do not cause changes to the cervix and are sometimes called false labor or practice contractions.
Cervix — The opening at the bottom of the uterus, which dilates or opens in order for the fetus to pass into the vagina or birth canal during the delivery process.
Contraction — A tightening of the uterus during pregnancy. Contractions may or may not be painful and may or may not indicate labor.

Treatment

The goal of treatment is to stop the premature labor and prevent the fetus from being delivered before it is full term. A first recommendation may be for the woman with premature contractions to lie down with feet elevated and to drink juice or other fluids. If contractions continue or increase, medical attention should be sought. In addition to bed rest, medical care may include intravenous fluids. Sometimes, this extra fluid is enough to stop contractions. In some cases, oral or injectable drugs like terbutaline sulfate, ritodrine, magnesium sulfate, or nifedipine must be given to stop the contractions. These are generally very effective; however, as with any drug therapy, there are risks of side effects. Some women may need to continue on medication for the duration of the pregnancy. Antibiotics may be prescribed if a vaginal or urinary tract infection is detected. If the membranes have already ruptured, it may be difficult or impossible to stop premature labor. If infection of the membranes that cover the fetus (chorioamnionitis) develops, the baby must be delivered.

Prognosis

If premature labor is managed successfully, the pregnancy may continue normally for the delivery of a healthy infant. Once symptoms of preterm labor occur during the pregnancy, the mother and fetus need to be monitored regularly since it is likely that premature labor will occur again. If the preterm labor cannot be stopped or controlled, the infant will be delivered prematurely. These infants that are born prematurely have an increased risk of health problems including birth defects, lung problems, mental retardation, blindness, deafness, and developmental disabilities. If the infant is born too early, its body systems may not be mature enough for it to survive. Evaluating the infant's lung maturity is one of the keys to determining its chance of survival. Fetuses delivered further into pregnancy and those with more mature lungs are more likely to survive.

Prevention

Smoking, poor nutrition, and drug or alcohol abuse can increase the risk of premature labor and early delivery. Smoking and drug or alcohol use should be stopped. A healthy diet and prenatal vitamin supplements (prescribed by the health care provider) are important for the growth of the fetus and the health of the mother. Pregnant women are advised to see a health care provider early in the pregnancy and receive regular prenatal examinations throughout the pregnancy. The health care provider should be informed of any medications that the mother is receiving and any health conditions that exist before and during the pregnancy.

Resources

Organizations

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Ave., White Plains, NY 10605. (914) 428-7100. resourcecenter@modimes.org. http://www.modimes.org.

Other

"Am I in Labor?" The Virtual Hospital Page. University of Iowa. http://www.vh.org.

labor

 [la´ber]
the physiologic process by which the uterus expels the products of conception (fetus or newborn and placenta), after 20 or more weeks of gestation. It may be divided into three stages: The first stage (dilatation) begins with the onset of regular uterine contractions and ends when the cervical os is completely dilated and flush with the vagina, thus completing the birth canal. The second stage (expulsion) extends from the end of the first stage until the expulsion of the infant is completed. The third stage (placental stage) extends from the expulsion of the child until the placenta and membrane are expelled and contraction of the uterus is completed. Called also accouchement and parturition.

Labor is believed to be triggered by the release of oxytocin and prostaglandins, after a fall in the levels of other hormones. Normally at the end of pregnancy oxytocin, which is stored in the posterior lobe of the pituitary gland, is released and stimulates contraction of the uterine muscles.

The progress and final outcome of labor are influenced by four factors: (1) the “passage” (the soft and bony tissues of the maternal pelvis); (2) the “powers” (the contractions or forces of the uterus); (3) the “passenger” (the fetus); and (4) the “psyche” (mother's emotional state, e.g., anxiety).

The mechanisms of labor (for a vertex presentation) consist of the following sequence of events: engagement (posterior occiput of fetus enters the pelvic outlet); flexion (of fetal head); descent (fetal head descends lower into the midpelvis); internal rotation (fetal head and body rotate so that the occiput is more anterior); extension (fetal head extends once the occiput is beneath the symphysis pubis); and external rotation (fetal head rotates back to position it had at engagement).
First Stage of Labor. The beginning of labor is usually indicated by one or more of the following signs: (1) show (passage from the vagina of small quantities of blood-tinged mucus); (2) breaking the “bag of waters” (normal rupture of membranes, indicated by a gush or slow leakage of amniotic fluid from the vagina); and (3) true labor contractions. The first two of these signs are almost always unmistakable. The contractions, however, can be confusing. braxton-hicks contractions, or “false labor pains,” can be distinguished from true labor contractions by the irregular time intervals between them and by their tendency to disappear when the patient changes position or gets up and walks about. True labor contractions are regularly spaced and usually start in the small of the back, or as a feeling of tightness in the abdomen, or of pressure in the pelvis. The contractions recur at shorter and shorter intervals, every three to five minutes, and become progressively stronger and longer lasting. The increase in the strength of contractions usually is accompanied by an increase in the amount of show because of rupture of capillaries in the dilating cervix.

This first stage of childbirth is known as the dilatation period. The uterus is like a large rubber bottle with a half-inch long neck that is almost closed. As the uterine muscles contract, the cervix becomes thinner (effacement) and more open (dilated) so that the neck of the uterus eventually resembles that of a jar more than that of a bottle.

The length of the first stage of labor varies with each individual patient, with an average of 8 to 12 hours in primiparous and 6 to 8 hours in multiparous women. It is related to the strength and effectiveness of the contractions and is a period when the mother is instructed to relax as much as possible and let the uterus do the work. Pushing or bearing down is not effective during this stage and is harmful in that it may cause a tearing of the cervix and will only serve to exhaust the woman. She is encouraged to rest and possibly to nap between contractions.

The second stage of labor may be heralded by symptoms of nausea, vomiting, irritability, the urge to bear down, or periods of feeling hot and then cold, signs of the period of transition from the first to the second stage.
Second Stage of Labor. This period, called the expulsion stage, usually is characterized by intense contractions that last for about one full minute and occur at 2 to 3 minute intervals. The cervix is fully dilated and the woman is able to help with this process by bearing down with each uterine contraction, using her abdominal muscles to help expel the infant. This stage varies from a few minutes to one to two hours.
Third Stage of Labor. In this stage the placenta detaches itself from the uterine wall and is expelled. The process takes about 15 minutes, and is painless.
Fourth Stage of Labor. This final stage is the stage of recovery and lasts 2 to 4 hours.
Patient Care. Once labor has begun the patient should have someone in constant attendance. She will derive much emotional support from one who is warm, kind, and understanding, and displays a genuine interest in her welfare and that of her infant. It is best to have the same person care for her through the entire labor and birth process.

During labor the strength, frequency, and duration of contractions are noted and recorded. It is expected that the contractions will increase in all three characteristics, but a sudden change in any one should be reported to the health care provider immediately. The rate, regularity, and volume of the fetal heart tones are checked and recorded periodically. Some apprehensive patients may be helped by allowing them to listen to the infant's heartbeat.

Food and fluids are withheld during active labor, but thirst may cause some discomfort and may be lessened by allowing the patient to moisten her lips with a gauze sponge or to suck on ice chips. Intravenous fluids are usually given. Frequent bathing of the face with a cool washcloth often helps relieve the flushed feeling brought about by the actual hard work being done by the mother. Frequent changing of her gown and of the pad protecting the bed linens may be necessary to keep her clean, dry, and comfortable.

If there is a support person with the woman during labor, that person should be instructed in ways he or she can help the patient and at the same time feel that he or she is making some contribution in this very important event. The support person may wish to participate in keeping a record of the contractions, or might appreciate the opportunity to listen to the fetal heart tones occasionally. If the patient feels that sacral support during each contraction helps mitigate the pain, the support person can be shown how to do this. Some supporters have attended classes for expectant parents and are prepared for their role during labor and delivery. Both the patient and the support person should be informed of the progress during labor so they can feel that something is being accomplished by their efforts.

The patient is encouraged to rest and relax between contractions so as to conserve her strength. She should not bear down until the cervix is fully dilated, since this effort will only serve to exhaust her and may cause lacerations of the cervix. After the cervix is fully dilated she can speed the birth process by holding her breath and contracting her abdominal muscles. Controlled breathing exercises learned in classes for expectant parents promote relaxation and aid labor.

Although serious complications rarely develop during labor, they can occur and must be watched for. Observations to report immediately include hyperactivity of the fetus; vaginal bleeding in excess of a heavy show; a rapid and irregular pulse and drop in blood pressure; sudden rise in blood pressure; and headache, visual disturbances, extreme restlessness, or rapidly developing edema. A sudden cessation of contractions or a contraction that does not relax may indicate a serious disturbance in the labor process. The appearance of meconium in the vaginal discharge may indicate fetal distress unless the infant is in a breech position. (See also fetal monitoring.)
Schematic representation of factors believed to have a role in starting labor. From Gorrie et al., 1994.
artificial labor induced labor.
dry labor a lay term indicating that in which the amniotic fluid escapes before contraction of the uterus begins.
false labor false pains.
induced labor that which is brought on by extraneous means, e.g., by the use of drugs that cause uterine contractions; called also artificial labor.
instrumental labor delivery facilitated by the use of instruments, particularly forceps.
missed labor that in which contractions begin and then cease, the fetus being retained for weeks or months.
precipitate labor delivery accomplished with undue speed.
premature labor expulsion of a viable infant before the normal end of gestation; usually applied to interruption of pregnancy between the twenty-eighth and thirty-seventh weeks.
preterm labor labor commencing before the end of 37 completed weeks of gestation; it can be arrested (see tocolysis) and does not necessarily lead to preterm delivery. Preterm labor can be treated by bed rest at home and use of a tokodynamometer with a recording unit that transmits data about uterine activity over the telephone to a monitoring station. Tocolytic drugs, including ritodrine hydrochloride and terbutaline, may be used to relax the uterine muscles.
spontaneous labor delivery occurring without artificial aid.

pre·ma·ture la·bor

onset of labor after 20 weeks' gestation and before the 37th completed week of pregnancy dated from the last normal menstrual period.

premature labor

pre·ma·ture la·bor

(prē'mă-chŭr' lā'bŏr)
Onset of labor before the 37th completed week of pregnancy dated from the last normal menstrual period.

labor

(la'bor) [L., labor, hard work]
Enlarge picture
SEQUENCE OF LABOR AND CHILDBIRTH
In pregnancy, the process that begins with the onset of repetitive and forceful uterine contractions sufficient to cause dilation of the cervix and ends with delivery of the placenta. Synonym: childbirth; parturition See: illustration

Traditionally, labor is divided into three stages. The first stage of labor, progressive cervical dilation and effacement, is completed when the cervix is fully dilated, usually 10 cm. This stage is subdivided into the latent phase and the active phase.

First stage (stage of dilation): This is the period from the onset of regular uterine contractions to full dilation and effacement of the cervix. This stage averages 12 hr in primigravidas and 8 hr in multiparas.

The identification of this stage is particularly important to women having their first baby. Its diagnosis is complicated by the fact that many women experience false labor pains, which may begin as early as 3 to 4 weeks before the onset of true labor. False labor pains are quite irregular, are usually confined to the lower part of the abdomen and groin, and do not extend from the back around the abdomen as in true labor. False labor pains do not increase in frequency and duration with time and are not made more intense by walking. The conclusive distinction is made by determining the effect of the pains on the cervix. False labor pains do not cause effacement and dilation of the cervix as do true labor pains. See: Braxton Hicks contractions

A reliable sign of impending labor is show. The appearance of a slight amount of vaginal blood-tinged mucus is a good indication that labor will begin within the next 24 hours. The loss of more than a few milliliters of blood at this time, however, must be regarded as being due to a pathological process. See: placenta previa

Second stage (stage of expulsion): This period lasts from complete dilatation of the cervix through the birth of the fetus, averaging 50 min in primigravidas and 20 min in multiparas. Labor pains are severe, occur at 2- or 3-min intervals, and last from a little less than 1 min to a little more than 112 min.

Rupture of the membranes (bag of water) usually occurs during the early part of this stage, accompanied by a gush of amniotic fluid from the vagina. The muscles of the abdomen contract involuntarily during this portion of labor. The patient directs all her strength to bearing down during the contractions. She may be quite flushed and perspire. As labor continues the perineum bulges and, in a head presentation, the scalp of the fetus appears through the vulvar opening. With cessation of each contraction, the fetus recedes from its position and then advances a little more when another contraction occurs. This continues until more of the head is visible and the vulvar ring encircles the head like a crown (therefore often called crowning).

At this time the decision is made concerning an incision in the perineum (episiotomy) to facilitate delivery. If done, it is most commonly a midline posterior episiotomy. When the head is completely removed out of the vagina it falls posteriorly; later the head rotates as the shoulders turn to come through the pelvis. There is usually a gush of amniotic fluid as the shoulders are delivered.

Third stage (placental stage): This is the period following the birth of the fetus through expulsion of the placenta and membranes. As soon as the fetus is delivered, the remainder of the amniotic fluid escapes. It will contain a small amount of blood. Uterine contractions return, and usually within 8 to 10 min the placenta and membranes are delivered. After this, there is some bleeding from the uterus. The amount may vary from 100 to 500 ml.

The amount of blood loss will vary with the size of the fetus, but the average is 200 ml. The probability that blood loss will exceed 500 ml is increased with a large fetus or multiple fetuses, as the placental attachment area on the uterine wall is larger and the uterus is more distended, meaning it does not contract as well after delivery of the fetus, placenta, and membranes. The above probability is less than 5% if the fetus weighs 5 lb (2268 g) or less. Other factors such as episiotomy or perineal laceration will also affect the amount of blood loss. See: birthing chair; Credé method for assisting with the expulsion of the placenta

Patient care

Often pregnant women and their partners or a labor coach who will be with them attend prenatal classes taught by obstetrical nurses to prepare the patient and family for labor, delivery, and care of the newborn. Such classes include exercises; breathing techniques; supportive care measures for labor, delivery, and the postpartum period; and neonatal care and feeding techniques. Expectant couples (or the pregnant woman and a support person) should attend classes together. The goals of expectant parent education are the birth of a healthy infant and a positive experience for the woman/couple. Labor and delivery may take place in a hospital, birthing center, or at home. Hospitals offer care in traditional labor and delivery rooms and, increasingly, in birthing rooms that simulate a homelike environment. Prenatal records are made available in order to review medical, surgical, and gynecological history; blood type and Rh; and esp. any prenatal problems in the pregnancy. If the mother is Rh negative and if the Rh status of the fetus is unknown or positive, the nurse will administer Rh immune globulin to the mother within 72 hr after delivery.

As part of the admission workup of the laboring woman, the nurse assesses vital signs, height and weight, fetal heart tone and activity, and labor status, i.e., condition of membranes, show, onset time of regular contractions, contraction frequency and duration, and patient anxiety, pain, or discomfort). Initial laboratory studies are carried out according to protocol. The obstetrician, resident physician or other house staff, nurse-midwife, lay midwife, or obstetrical nurse examines the patient, depending on the site and policy. The abdomen is palpated to determine fetal position and presentation (Leopold maneuvers), and a sterile vaginal examination determines cervical dilatation and effacement, fetal station, and position of the presenting part. The attending nurse or midwife monitors and assesses fetal heart rate and the frequency and duration of contractions, using palpation and a fetoscope or electronic monitoring. The frequency of assessment and repetition of vaginal examination are determined by the patient's labor stage and activity and by fetal response. In the past, admission to a labor suite usually included a perineal shave and enema in preparation for delivery, but these procedures have been largely discontinued and are currently done only if prescribed for a particular patient. The patient should urinate and have a bowel movement, if possible. Bladder distention is to be avoided, but catheterization is carried out only if all other efforts to encourage voiding in a patient with a distended bladder fail. The perineum is cleansed (protecting the vaginal introitus from entry of cleansing solutions) and kept as clean as possible during labor. Special cleansing is performed before vaginal examination and delivery, as well as after expulsion of urine or feces.

First stage: The patient may be alert and ambulating, depending on membrane status, fetal position, and labor activity. Electrolyte-rich oral liquids may be prescribed, or intravenous therapy initiated. The nurse supports the patient and her partner or other support person and monitors the progress of the labor and the response of the fetus, notifying the obstetrician or midwife of any abnormal findings. When membranes rupture spontaneously or are ruptured artificially by the midwife or obstetrician, the color and volume of the fluid and the presence of meconium staining or unusual odor are noted. To distinguish it from a sudden spurt of urine having a slightly acid pH, the fluid may be tested for alkaline pH using nitrazine paper. The fetal heart rate, an indicator of fetal response to the membrane's rupture, is noted. Noninvasive pain relief measures are provided, prescribed analgesia is administered as required by the individual patient, and regional anesthetic use is monitored. Patient-controlled epidural anesthesia (PCEA) or continuous epidural anesthesia is frequently employed, based on patient satisfaction regarding its timeliness and effectiveness, and the patient's preference for having pain management under her control.

Second stage: The patient may deliver in any agreed-on position, including lithotomy or modified lithotomy, sitting, or side lying, in a birthing chair, in a birthing bed, or on a delivery table. The nurse, midwife, or physician continues to monitor the patient and fetus; prepares the patient for delivery (cleansing and draping); sets up delivery equipment; and supports the father or support person (positioned near the patient's head), positioning the mirror or TV monitor to permit viewing of delivery by the couple. The nurse also notes and documents the time of delivery, determines the infant’s Apgar score, and provides initial infant care after delivery, including further suctioning of the nasopharynx and oropharynx as necessary (initial suctioning is done by the deliverer before delivering the infant's shoulders), drying and warming the infant (head covering, blanket wrap, or thermal warmer), application of cord clamp (after the deliverer double-clamps the cord and cuts between the clamps), and positive identification (footprints of infant and thumb prints or fingerprints of mother, and application of numbered ankle and wrist band to the infant and wrist band to the mother). Eye prophylaxis for gonorrhea and Chlamydia may be delayed up to 2 hr to facilitate eye contact and to enhance maternal-infant bonding, or may be refused by the parents, on signing of an informed consent. An Apgar score of the infant's overall condition is obtained at 1 min and 5 min after the birth. The infant in good condition is placed on the mother's chest or abdomen for skin to skin contact. This position enhances bonding and maintains infant warmth. Alternately, the infant is put to the breast, and the woman/couple is encouraged to inspect and interact with the infant. An infant in distress is hurried to the nursery, usually with the father or support person attending, so that specialized care can be provided by nursery and neonatal-nurse specialists, and a pediatrician. If the infant is critically ill, its birth may be attended by a chaplain, and photographs may be taken to assist the parents in dealing with the life, critical time, and possible death of the infant.

Third stage: The nurse continues to monitor the status of the patient and the fundus through delivery of the placenta and membranes (documenting the time), examination of the vagina and uterus for trauma or retained products, and repair of any laceration or surgical episiotomy. The placenta is examined to ascertain that no fragments remain in the uterus. The perineal area is cleansed and the mother is assisted to a comfortable position and covered with a warm blanket.

Fourth stage: The nurse continues to observe the patient closely and is alert for hemorrhage or other complications through frequent assessment, including monitoring vital signs, palpating the fundus for firmness and position in relation to the umbilicus at intervals (determined by agency policy or patient condition), and massaging the fundus gently or administering prescribed oxytocic drugs to maintain or assist uterine contraction and to limit bleeding. The character (including presence, size, and number of clots) and volume of vaginal discharge or lochia are assessed periodically; the perineum is inspected and ice applied as prescribed, and the bladder is inspected, palpated, and percussed for distention. The patient is encouraged to void, and catheterization is performed only if absolutely necessary. The nurse notifies the obstetrician or midwife if any problems occur or persist. This period also is used for parent-infant bonding, because the infant is usually awake for the first hour or so after delivery. The mother can breast-feed if she wants to, and the immediate family couple can inspect the infant. The nurse supports the family's responses to the newborn, as well as to the labor and delivery experience. The infant is then taken to the nursery for initial infant care.

Early postpartum period: Once the infant's temperature has stabilized, measurements have been taken (length, head and chest circumference, weight), and other prescribed care carried out, the infant may be returned to the mother's side (in its crib carrier). The nurse continues to assess the mother's physical and psychological status after delivery, checking the fundus, vulva, and perineum according to policy; inspects the mother's breasts and assists her with feeding (whether by breast or bottle) and with measures to prevent lactation as desired; helps the mother to deal with other responsibilities of motherhood; and carries out the mandated maternal teaching program, including providing written information for later review by the patient. In hospitals or birthing centers, the nurse prepares the mother for early discharge to the home setting and arranges for follow-up care as needed and available. In many settings, the nurse makes follow-up calls or visits to the mother during the early postpartum period or encourages her to call in with concerns, or she may receive follow-up visits by a caregiver from her health maintenance organization. The mother may also be referred to support groups, such as the La Leche League, Nursing Mothers' Club, and others as available in the particular community.

active labor

Regular uterine contractions that result in increasing cervical dilation and descent of the presenting part. This encompasses the active phase of stage 1, as well as stages 2 and 3 of labor.

arrested labor

Failure of labor to proceed through the normal stages. This may be due to uterine inertia, obstruction of the pelvis, or systemic disease.

artificial labor

Induction of labor.

augmented labor

Induction of labor.

back labor

Labor involving malposition of the fetal head with the occiput opposing the mother's sacrum. The laboring woman experiences severe back pain.
See: persistent occiput posterior

complicated labor

Labor occurring with an accompanying abnormal condition such as hemorrhage or inertia.

dry labor

A colloquial, imprecise term for labor associated with extensive loss of amniotic fluid related to premature rupture of membranes.

dysfunctional labor

Abnormal progress of dilation and/or descent of the presenting part.

false labor

Uterine contractions that occur before the onset of labor. The contractions do not result in dilation of the cervix. They may resolve spontaneously or continue until effective contractions occur and labor begins. Synonym: missed labor (1) See: Braxton Hicks contractions

hypertonic labor

A condition in which frequent, painful, but poor-quality contractions fail to accomplish effective cervical effacement and dilation. Hypertonicity usually occurs in the latent phase of labor and most often is related to fetal malpresentation and cephalopelvic disproportion.

hypotonic labor

A condition during the active phase of labor in which contractions are inadequate in frequency, intensity, and duration and are ineffective in causing cervical dilation, effacement, or fetal descent. Hypotonicity usually occurs after the woman has entered the active phase of labor and most often is related to uterine overdistention, fetal macrosomia, multiple pregnancy, or grand multiparity.

instrumental labor

Labor completed by mechanical means, e.g., the use of forceps or vacuum assist.

missed labor

1. False labor.
2. Labor in which true labor pains begin but subside. This may be a sign of a dead fetus or extrauterine pregnancy.

normal labor

Progressive dilation and effacement of the cervix with descent of the presenting part.

obstructed labor

Interference with fetal descent related to malposition, malpresentation, and cephalopelvic disproportion.

precipitate labor

Labor marked by sudden onset, rapid cervical effacement and dilation, and delivery within 3 hr of onset.

premature labor

Preterm labor

preterm labor

Labor that begins before completion of 37 weeks from the last menstrual period. The condition affects 7% to 10% of all live births and is one of the most important risk factors for preterm birth, the primary cause of perinatal and neonatal mortality. Although associated risk factors do exist, in most cases the cause is unknown. Synonym: premature laborpremature rupture of membranes; prematurity;

Note: Treatment for active premature labor is best managed in a regional perinatal intensive care center, where staff members are prepared to handle the required care and treatment, and so that the neonate can remain in the same setting as the mother, rather than being transferred alone for neonatal intensive care after delivery.

Patient care

In-hospital management: The patient is prepared for the use of cardiac, uterine, and fetal monitors along with intravenous therapy. Maternal vital signs and fetal heart rate (FHR) are monitored. If prescribed a tocolytic agent (beta-adrenergic drug) is administered intravenously; the infusion rate is increased every 10 to 30 min, depending on uterine response, but never exceeds a rate of 125 ml/hr. Uterine activity is monitored continuously; vital signs and FHR are checked every 15 min. Maternal pulse should not exceed 140/min; FHR should not exceed 180 bpm. When counting respiratory rate, breath sounds are noted, and the lungs are auscultated at least every 8 hr. The patient is assessed for desired response and adverse effects to treatment and is taught about symptoms she may expect and should report. If signs of drug toxicity occur, the medication is stopped. The intravenous line is kept open with a maintenance solution, and the prescribed beta-blocker as an antidote is prepared and administered. The patient is placed in high Fowler's position, and oxygen is administered. Cardiac rate and rhythm, blood pressure, respiratory rate, auscultatory sounds, and FHRs are closely monitored to evaluate the patient's response to the antidote. If no complications are present, absolute bed rest is maintained throughout the infusion, with the patient in a left-lateral position or supine with a wedge under the right hip to prevent hypotension. Antiembolism stockings are applied, and passive leg exercises are performed. A daily fluid intake of 2 to 3 L is encouraged to maintain adequate hydration, and fluid intake and output are measured. The patient is weighed daily to assess for overhydration. The patient is instructed in methods to deal with stress. Health care providers should respond to parental concern for the fetus with empathy, but never with false reassurance. Fetal fibronectin enzyme immunoassay may be carried out on a sample of vaginal secretions taken from the posterior vaginal fornix; the patient should understand that this test can help assess the risk of preterm delivery within 7 days from the sampling date. As prescribed, a glucocorticoid is administered to stimulate fetal pulmonary surfactant production.

Patients who undergo in-house therapy often receive magnesium sulfate, which helps restore the patient's beta-2 receptor sensitivity (thus improving the effectiveness of terbutaline) and decrease uterine contractions. The patient may be discharged on oral or subcutaneous tocolytic therapy. Intravenous therapy may be employed using a portable micropump that can deliver a basal rate or programmed intermittent bolus doses at predetermined times when the patient's circadian rhythms are known to increase uterine activity.

Home management: The plan for at-home care must target individuals whom the woman can call upon to help with home management. A social service referral can help the family access available community and financial assistance. Home health care nurses assist the patient to carry out the plan, provide ongoing emotional support, and evaluate fetal and patient response to therapy.

The treatment regimen is reviewed with the family, and written instructions are provided to help those involved to cooperate. The patient is maintained on bed rest (left-side, supine, with head on small pillow, feet flat or elevated) to increase uterine perfusion and to keep fetal pressure off the cervix. The patient usually is allowed out of bed only to go to the bathroom. The women's physical and psychological rest are the highest priority, as anxiety is known to compromise uterine blood flow. Paid or voluntary helpers must care for other children and all household chores. The patient's tocolytic therapy (most frequently using terbutaline) is scheduled around the clock (with food if desired), and the patient is taught about its action and adverse effects. The patient must be able to count her pulse, and is instructed to report a rate above 120/min. The patient also is taught about symptoms to report (palpations, tremors, agitation, nervousness) and how to palpate for contractions twice each day. Home uterine activity monitoring may be employed, with the patient or home health care provider recording uterine activity for an hour twice daily. The perinatal nurse analyzes the results. If contractions exceed a predetermined threshold, the patient is advised to drink 8 to 12 ounces of water, rest, then empty her bladder and monitor uterine activity for another hour. The process can reduce unnecessary visits to the medical setting, and increase the patient's peace of mind. The patient is encouraged to drink water throughout the day to prevent dehydration and reduce related uterine irritability. She also is warned not to take over the counter drugs without her obstetrician's approval. The patient is taught how to use sedation, if prescribed. Avoidance of activities that could stimulate labor is emphasized; these include sexual and nipple stimulation. Personal hygiene is reviewed, and the patient is made aware of signs of infection to report. A nonstress test may be performed weekly at home or in a medical setting, depending on the acuity of the situation and on maternal health factors (diabetes, pregnancy-induced hypertension [PIH]). The patient usually is provided with a 24-hr phone link to perinatal nurses in the health care system, who may contact her twice daily to discuss her situation. She is taught what to do in an emergency (bright red bleeding, membrane rupture, persisting contractions, decreased or absent fetal activity). If an incompetent cervix has been diagnosed based on the patient’s history, insertion of a purse-string suture (cerclage) as reinforcement at 14 to 18 weeks gestation may prevent premature labor. If labor is inevitable, it is carried out as for a low-birth-weight, readily compromised fetus. During the postpartum period, care focuses on helping the family to understand their infant's special needs, and to participate as fully as possible in care, or, in a worst-case scenario, to come to terms with the baby's death. In such a case, the family is assisted in their grieving, with encouragement to hold the swaddled infant, and look at pictures of the child if they are able. Psychological counseling may be required.

primary dysfunctional labor

protracted labor.

prodromal labor

The initial changes that precede actual labor, usually occurring 24 to 48 hr before the onset of labor. Some women report a surge of energy. Findings include lightening, excessive mucoid vaginal discharge, softening and beginning effacement of the ripe cervix, scant bloody show associated with expulsion of the mucus plug, and diarrhea.

prolonged labor

Abnormally slow progress of labor, lasting more than 20 hr.
See: dystocia

prolonged latent phase labor

Abnormally slow progress of the latent phase, lasting more than 20 hr in a nullipara or 14 hr in a multipara.
See: dystocia

protracted labor

Abnormally slow dilation of the cervix in the active phase of labor; defined as less than 1.2 cm/hr in a nullipara and 1.5 cm/hr in a multipara.. .
Synonym: protraction disorderprimary dysfunctional labor See: arrested labor; precipitate labor

spontaneous labor

Labor that begins and progresses without pharmacological, mechanical, or operative intervention.

stage I labor

labor;

stage II labor

labor;

trial of labor

Permitting labor to continue long enough to determine if normal vaginal birth appears to be possible, e.g., in vaginal birth after cesarean delivery.
References in periodicals archive ?
Identify and understand important and diverse types of therapeutics under development for Premature Labor (Tocolysis)
Terbutaline Sulfate, used to prevent premature labor contractions, can on rare occasions produce acute muscular weakness.
On the street, people say cocaine causes uterine contractions and premature labor.
A snapshot of the global therapeutic scenario for Premature Labor (Tocolysis).
In this study, 45 women who experienced premature labor (before 37 weeks gestation) were randomly divided into treatment and observation groups.
Doctors currently prescribe indomethacin to prevent premature labor.
There are reasons to hope that the COX2 inhibitors may stop premature labor, have anti-cancer effects, and prevent the progression of Alzheimer's disease.
Job strain has been found to raise blood pressure and to increase the chance of smoking, both of which can contribute to premature labor.
Medication is given until premature labor is successfully suppressed or until the baby is delivered.
The panel recommends that two corticosteroid injections be given to women who are in weeks 24 to 34 of pregnancy, and who arrive at a hospital experiencing premature labor or are at risk of doing so.
Global Markets Direct's, 'Premature Labor (Tocolysis) - Pipeline Review, H1 2012', provides an overview of the Premature Labor (Tocolysis) therapeutic pipeline.
When there is an infection in the uterus, the onset of premature labor appears to have survival value," Romero said.