WHAT IS IT?
Premature (or preterm) labor is labor contractions that occur after twenty weeks but before 36 weeks into the pregnancy. As opposed to the irregular nature of false labor contractions, premature labor contractions occur at least twice every ten minutes for at least 30 minutes. In addition, either cervical dilation or thinning (effacement) of the cervix is present. A complication of five to ten percent of all pregnancies, premature labor is associated with increased infant illness (morbidity) and death (mortality). Premature labor may be associated with elevated blood pressure, nonexistent or poor prenatal care, multiple pregnancies, inadequate or excessive weight gain, pre-existing medical conditions (such as diabetes, heart problems), infection, anemia,
preeclampsia, alcohol or drugs,
cigarette smoking, short interval between pregnancies, previous preterm labor, history of infertility, surgical complications, birth defects (congenital anomalies), Rh-negative mother with an Rh-positive fetus (isoimmunization), and in women who have given birth seven or more times (grand multiparity). The risk of premature labor is greatest in women under fifteen years or older than 35.
HOW IS IT DIAGNOSED?
History: Symptoms of premature labor may include contractions, menstrual-like cramps, backache, pelvic pressure, vaginal bleeding or discharge, or diarrhea. Premature rupture of membranes often occurs with the onset of premature labor.
Physical exam reveals contractions, dilation and/or effacement of the cervix, and vaginal bleeding.
Tests include complete blood count (CBC) with differential and hematologic workup (hematocrit, hemoglobin, serum chemistries, prothrombin time, partial thromboplastin time) in cases associated with hemorrhage. Electrolytes and serum glucose testing are done in cases requiring suppression of contractions (tocolysis). A urine culture and sensitivity may be done to rule out
urinary tract infection. Ultrasound scanning is used to determine fetal size, position and placental location. An amniocentesis to obtain fluid for assessing fetal maturity is performed. A fibronectin test may help predict premature labor during the seven days following the test.
HOW IS IT TREATED?
Treatment will depend on whether or not the labor is allowed to continue. Critical factors in this decision include number of weeks of pregnancy, fetal maturity, and the amount of dilation and effacement of the cervix. Treatment may include bedrest, sedation, and increased fluid intake (hydration). With this regimen, up to 80% of pregnancies can be continued for at least two more weeks. In more urgent situations, labor can often be stopped with drugs (beta-mimetic adrenergic agents, magnesium sulfate, prostaglandin synthetase inhibitors, and calcium channel blockers). If the labor can be stopped, the individual may have the cervix bound (cervical cerclage). Gestational age should be assessed, and drugs (corticosteroids) to mature the fetal lungs may be administered. If the labor cannot be stopped, the individual is transferred to a hospital with a neonatal intensive care unit. Internal fetal monitoring is done to determine the most effective mode of delivery.
WHAT MIGHT COMPLICATE IT?
Complications include infection, increased morbidity and mortality of the premature infant, and hemorrhage.
PREDICTED OUTCOME
Most cases (70%) of premature labor can be successfully stopped with only bedrest. About 25% of cases will require the administration of drugs to stop the labor. If labor cannot be stopped, a premature infant will be delivered.
ALTERNATIVES
This could be "false labor" (Braxton Hicks' contractions).
APPROPRIATE SPECIALISTS
Obstetrician or gynecologist, perinatologist, and pediatrician.
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