Preterm Labor and Birth Notes

Preterm Labor & Birth

Objectives

• Identify risk factors for preterm birth and premature rupture of membranes.

• Discuss nursing management in preterm labor.

• Describe the role and responsibility of the nurse in emergency childbirth situations.

Preterm Labor and Birth

• Preterm labor: Cervical changes and uterine contractions occurring between 20 and before 37 weeks of pregnancy.

• Preterm birth: Any birth that occurs between 20 and before completion of 37 weeks of pregnancy.

• Approximately 12% of all live births are preterm.

Preterm Labor

• Regular contractions along with a change in cervical effacement or dilation, or presentation with regular uterine contractions and cervical dilation of at least 2 cm.

• Preterm birth: any birth that occurs between 20 0/7 and 36 6/7 weeks of gestation.

• Decreasing rates of preterm birth in the last decade due to:

  • Improved fertility practices that reduce the risk for higher-order multiple gestations.

  • Quality improvement programs that limit scheduled late preterm and near-term births to only those with valid indications.

  • Increased use of strategies to prevent recurrent preterm birth.

Sub-Categories of Preterm Birth

• Very preterm: Less than 32 weeks of gestation.

• Moderately preterm: 32 to 34 weeks of gestation.

• Late preterm: 34 0/7 to 36 6/7 weeks of gestation.

Preterm Birth Versus Low Birth Weight

• Preterm birth or prematurity: Length of gestation regardless of birth weight.

  • More dangerous than birth weight alone because less time in the uterus correlates with immaturity of body systems.

• Low birth weight: Less than or equal to 2500 grams at birth.

  • Many potential causes, including preterm birth and intrauterine growth restriction (IUGR).

Spontaneous Versus Indicated Preterm Birth

• Spontaneous: 75% of preterm births.

• Indicated: 25% of preterm births.

Causes of Spontaneous Preterm Labor and Birth

• Multifactorial, involving multiple pathologic processes.

• Infection is the only definitive factor.

• Congenital structural abnormalities of the uterus.

• Placental causes.

• Maternal and fetal stress.

• Uterine overdistention.

• Allergic reaction.

• Decrease in progesterone.

Predicting Spontaneous Preterm Labor and Birth

• Known risk factors.

• Biochemical markers:

  • Fetal fibronectin (“biologic glue”).

  • Salivary estriol.

  • Cost of determining biochemical markers is high.

• Endocervical length (ultrasound).

Preterm Labor: Nursing Assessment #1

• Risk factors.

• Subtle signs.

• Contraction pattern: Four contractions every 20 minutes or eight contractions in 1 hour.

• Laboratory and diagnostic testing:

  • Complete blood count.

  • Urinalysis.

  • Amniotic fluid analysis.

  • Fetal fibronectin.

  • Cervical length via transvaginal ultrasound.

  • Salivary estriol.

  • Home uterine activity monitoring.

Risk Factors for Preterm Birth

• Small stature.

• Multi-fetal pregnancy.

• Hydramnios.

• Bleeding.

• Placental problems.

• Infections, including urinary tract infections (UTIs).

• Premature Rupture of Membranes (PROM).

• Fetal anomalies.

• Maternal anemia.

• Domestic violence.

• Medical diseases (diabetes mellitus, hypertension, anemia).

Amniotic Fluid

• Alterations in amniotic fluid volume can be associated with problems in the fetus.

• Oligohydramnios: Too little amniotic fluid (<500 mL at term).

  • Associated with uteroplacental insufficiency and fetal renal abnormalities.

  • Higher risk of surgical births and low-birth-weight infants.

• Hydramnios: Too much amniotic fluid (>2,000 mL at term).

  • Associated with maternal diabetes, neural tube defects, chromosomal deviations, and malformations of the central nervous system and/or gastrointestinal tract.

  • These malformations prevent normal swallowing of amniotic fluid by the fetus.

Fetal Fibronectin

• Fetal Fibronectin: A glycoprotein produced by the chorion.

• A negative fetal fibronectin test is extremely helpful.

• From weeks 24 to 34, there should be very little FbN detectable in vaginal secretions.

• In studies, less than 10% of women with a negative result delivered before 35 weeks of pregnancy.

• A positive result is not helpful. Seven out of 10 women with a positive fetal fibronectin will stay pregnant past 35 weeks.

Predicting Spontaneous Preterm Labor and Birth

• Risk factors.

• Cervical length:

  • Cervical length >30 mm in the 2nd and 3rd trimester is unlikely to result in premature birth.

• Fetal Fibronectin (fFN) Test:

  • fFN is a glycoprotein “glue” found in plasma and produced during fetal life.

  • The test is used to predict who will not go into preterm labor, because its negative predictive value is high.

  • Women with a negative test have less than a 1% chance of giving birth within two weeks.

Salivary Estriol

• Estriol is a form of estrogen produced by the placenta.

• 3 to 5 weeks before labor begins (even when the labor is preterm), the amount of estriol in the placenta increases dramatically.

• Less reliable than the fetal fibronectin test.

• Women who received an abnormal result on the test never developed preterm labor.

Cervical Length Measuring

• Performed using a transvaginal ultrasound to measure the cervix.

• Measure cervical length and width.

• Best obtained between 16- and 24-weeks gestation.

• Cervical length varies during pregnancy but measured fairly reliably after 16 weeks.

• Cervical length of 3cm or more indicates that delivery within 14 days is unlikely.

Care Management: Prevention

• Preventive strategies to address risk factors.

• Education about early symptoms of preterm labor.

• Teach what to do if symptoms occur.

• Women may ignore symptoms because of:

  • Ignorance regarding significance.

  • Belief that symptoms are expected during pregnancy.

Incompetent Cervix

• Cervical Cerclage: Shirodkar cerclage, McDonald cerclage, Transabdominal cerclage.

• Normal Cervix: >30 mm. Narrowed cervical canal. No preterm labor. Negative fetal fibronectin.

• Incompetent Cervix: Uterine contractions are present.

  • Cervical length is 20-30 mm: Positive fetal fibronectin and Preterm labor.

  • Cervical length is <20 mm: Positive fetal fibronectin and Preterm labor.

Care Management – cont’d

• Early recognition and diagnosis:

  • Gestational age between 20 and 37 weeks.

  • Uterine activity (contractions).

  • Progressive cervical change.

  • Effacement of 80%.

  • Cervical dilation of 2 cm or greater.

Care Management – cont’d: Therapeutic Management

• Risk prediction.

• Tocolytic drugs:

  • There are no clear first-line drugs to manage preterm labor.

  • May prolong pregnancy for 2 to 7 days while steroids can be given for fetal lung maturity.

• Antibiotic prophylaxis for women with group B streptococcus.

Subtle Symptoms of Pre-Term Labor

• Change in vaginal discharge with mucous or blood.

• Pelvic pressure (pushing down sensation).

• Low, dull backache.

• Menstrual-like cramps.

• UTI symptoms.

• GI upset, nausea, vomiting, diarrhea.

• Heaviness or aching thighs.

• Uterine contractions with or without pain.

• More than 6 contractions/hr.

Teaching to Prevent Preterm Labor

• Avoid traveling for long distances in cars, trains, planes, or buses.

• Avoid lifting heavy objects, such as laundry, groceries, or a young child.

• Avoid performing hard, physical work, such as yard work, moving furniture, or construction.

• Mild to moderate levels of exercise are permitted such as walking daily.

• Achieve an appropriate pre-pregnancy weight.

• Achieve adequate iron stores through balanced nutrition.

• Wait at least 18 months between pregnancies.

• Visit a dentist in early pregnancy to evaluate and treat any periodontal disease.

• Enroll in a smoking cessation program if you are unable to quit on your own.

• Curtail sexual activity until after 37 weeks if experiencing preterm labor symptoms.

• Consume a well-balanced nutritional diet to gain appropriate weight.

• Avoid the use of substances such as marijuana, cocaine, and heroin.

• Identify factors and areas of stress in your life, and use stress management techniques to reduce them.

• If you are experiencing intimate partner violence, seek resources to modify the situation.

• Recognize the signs and symptoms of preterm labor and notify your birth attendant if any occur:

  • Uterine contractions, cramping, or low back pain.

  • Feeling of pelvic pressure or fullness.

  • Increase in vaginal discharge.

  • Nausea, vomiting, and diarrhea.

  • Leaking of fluid from the vagina.

• If you are experiencing any of these signs or symptoms, do the following:

  • Stop what you are doing and rest for 1 hour.

  • Empty your bladder.

  • Lie down on your side.

  • Drink two to three glasses of water.

  • Feel your abdomen and make note of the hardness of the contraction. Call your health care provider and describe the contraction as:

    • Mild if it feels like the tip of the nose

    • Moderate if it feels like the tip of the chin

    • Strong if it feels like your forehead

Care Management – cont’d: Lifestyle Modifications

• Activity restrictions

• Bed rest

• Limited work

• Restriction of sexual activity

• Home care

• Environmental modification

• Home uterine monitoring

Care Management – cont’d: Suppression of Uterine Activity

• Tocolytics – goal is to delay birth long enough to institute interventions that delay neonatal morbidity and mortality.

• Magnesium sulfate is most commonly used.

• Beta adrenergics.

• Nifedipine.

• Indomethacin.

Tocolytics

• Research has demonstrated that a gain of 48 hours to several days is the best outcome that can be expected with the use of tocolytics.

• The best reason to use tocolytic therapy is to achieve sufficient time to administer Steroids (glucocorticoids) in an effort to accelerate fetal lung maturity and reduce the severity of respiratory complications in preterm infants.

Medications with Tocolytic Properties

• Magnesium sulfate.

• Nifedipine.

• Indomethacin.

Medications Used with Preterm Labor

• Magnesium sulfate:

  • Action/Indication: Relaxes uterine muscles to stop irritability and contractions, to arrest uterine contractions for preterm labor (off-label use). Has been used in seizure prophylaxis and treatment of seizures in preeclamptic and eclamptic clients for almost 100 years.

  • Nursing Implications:

    • Administer IV with a loading dose of 4-6 g over 15-30 minutes initially, and then maintain infusion at 1-4 g/hr.

    • Assess vital signs and deep tendon reflexes (DTRs) hourly; report any hypotension or depressed or absent DTRs.

    • Monitor level of consciousness; report any headache, blurred vision, dizziness, or altered level of consciousness.

    • Perform continuous electronic fetal monitoring; report any decreased FHR variability, hypotonia, or respiratory depression.

    • Monitor intake and output hourly; report any decrease in output (<30 mL/hr).

    • Assess respiratory rate; report respiratory rate <12 breaths/min; auscultate lung sounds for evidence of pulmonary edema.

    • Monitor for common maternal side effects, including flushing, nausea and vomiting, dry mouth, lethargy, blurred vision, and headache.

    • Assess for nausea, vomiting, transient hypotension, and lethargy.

    • Assess for signs and symptoms of magnesium toxicity, such as decreased level of consciousness, depressed respirations and DTRs, slurred speech, weakness, and respiratory and/or cardiac arrest.

    • Have calcium gluconate readily available at the bedside to reverse magnesium toxicity.

• Indomethacin (Indocin):

  • Action/Indication: Inhibits prostaglandins, which stimulate contractions; inhibits uterine activity to arrest preterm labor.

  • Nursing Implications:

    • Continuously assess vital signs, uterine activity, and FHR.

    • Administer oral form with food to reduce gastrointestinal irritation.

    • Do not give to women with peptic ulcer disease.

    • Schedule ultrasound to assess amniotic fluid volume and function of ductus arteriosus before initiating therapy; monitor for signs of maternal hemorrhage.

    • Be alert for maternal adverse effects such as nausea and vomiting, heartburn, rash, prolonged bleeding time, oligohydramnios, and hypertension.

    • Monitor for neonatal adverse effects, including constriction of ductus arteriosus, premature ductus closure, necrotizing enterocolitis, oligohydramnios, and pulmonary hypertension.

    • Contraindicated in >32 weeks' gestations, fetal growth restriction, history of asthma, urticaria, or allergic-type reactions to aspirin or nonsteroidal antiinflammatory drugs.

• Nifedipine (Procardia):

  • Action/Indication: Blocks calcium movement into muscle cells, inhibits uterine activity to arrest preterm labor.

  • Nursing Implications:

    • Use caution if giving this drug with magnesium sulfate because of increased risk for hypotension.

    • Monitor blood pressure hourly if giving with magnesium sulfate; report a pulse rate >110 bpm.

    • Monitor for fetal effects such as decreased uteroplacental blood flow manifested by fetal bradycardia, which can lead to fetal hypoxia.

    • Monitor for adverse effects, such as flushing of the skin, headache, transient tachycardia, palpitations, postural hypertension, peripheral edema, and transient fetal tachycardia.

    • Contraindicated in women with cardiovascular disease or hemodynamic instability.

• Betamethasone (Celestone):

  • Action/Indication: Promotes fetal lung maturity by stimulating surfactant production; prevents or reduces risk of respiratory distress syndrome and intraventricular hemorrhage in the preterm neonate less than 34 weeks' gestation.

  • Nursing Implications:

    • Administer two doses intramuscularly 24 hours apart.

    • Monitor for maternal infection or pulmonary edema.

    • Educate parents about potential benefits of drug to preterm infant.

    • Assess maternal lung sounds and monitor for signs of infection.

Tocolytics Contraindications

• Mnemonic: CCLAPP

  • C: Chorioamnionitis

  • C: Congenital anomaly

  • L: Late pregnancy (>34 weeks)

  • A: Advanced labor

  • P: Placenta abruption

  • P: Pre-eclampsia

Preterm Labor Summary

• What is it? Uterine contractions WITH cervical changes between 20-37 weeks gestation.

• Signs & Symptoms: Vaginal discharge, cervical dilation, regular contractions.

• Risk Factors: Infection, multifetal pregnancy, hydramnios, smoking, substance abuse, diabetes, hypertension, placenta previa, premature rupture of membranes.

• Diagnosis: Test vaginal secretions for the presence of fetal fibronectin.

• Nifedipine: Calcium channel blocker, suppresses contractions. Watch for orthostatic hypotension.

• Magnesium sulfate: relaxes the smooth muscle in the uterus.

  • Watch for magnesium toxicity: decreased deep tendon reflexes. urine output <30 ml/hr, respiratory depression).

  • Administer calcium gluconate for toxicity

• Indomethacin: NSAID that blocks prostaglandin synthesis, therefore suppressing labor.

• Betamethasone: Glucocorticoid that promotes fetal lung maturity (given 24-48 hrs prior to birth).

Care Management – cont’d: Promotion of Fetal Lung Maturity

• Antenatal glucocorticoids

• Recommended by NIH to all women at risk for preterm labor

• Reduces the incidence of:

  • Respiratory Distress Syndrome

  • Necrotizing enterocolitis

  • Intraventricular hemorrhage

  • Death

Fetal Lung Maturity: Steroids

• The most common steroid, betamethasone (Celestone), is given IM 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.

• Multiple studies have shown that prenatal corticosteroids are very safe for mothers and babies (Roberts and Dalziel, 2010).

Care Management – cont’d: Management of Inevitable Preterm Birth

• Labor progressed to cervical dilation of 4 cm is likely to lead to inevitable preterm birth.

• May rapidly progress through labor.

• A very small fetus can deliver through a cervix not fully dilated.

• Nurses must be able to handle emergency deliveries.

Question 1

• A woman in preterm labor at 33 weeks of gestation receives two 12-mg doses of betamethasone intramuscularly. The purpose of this pharmacologic treatment is to:

  • None of the above

Question 2

• A woman with premature labor is receiving magnesium sulfate. What is an indication that the therapy is working?

  • Absence of regular contractions

Question 3

• A woman with preterm labor is receiving magnesium sulfate. Which finding would require the nurse to intervene immediately?

  • None of the above