Problems During Labor and Delivery

Preterm Labor Most labors occur within 2 weeks of the due date. Labor occurring prior to the 38th week of pregnancy is preterm labor, although definitions vary depending on the clinical circumstances.  
 

While delivering a little bit early usually poses no particular problem for the mother or the baby, more significant amounts of prematurity pose more significant risks for the infant. Of these, immaturity of the respiratory tree is among the most hazardous, but other organs can also be a problem. 
 

The cause of preterm labor is unknown, but in about half the cases, it is associated with detectable intrauterine infection. Another significant number are associated with placental abruption. 
 

Our instincts are to try to prevent preterm delivery to avoid the morbidity associated with it. This instinct is based on the premise that the problem is primarily one of prematurity. If, however, preterm labor in a particular patient is just a symptom of an underlying problem (infection, fetal stress, etc.), then vigorous attempts to prevent delivery, when successful, may only delay treatment of the underlying problem. Further, the medications commonly used to prevent premature delivery have significant side effects and risks. For these reasons, judgment is used to decide who should be treated for preterm labor and who shooed be allowed to deliver. In many civilian hospitals, no attempt is made to arrest labor after the 34th week. 
 

Threatened preterm labor consists of regular, frequent contractions (every 10 minutes) that do not lead to a change in the cervix. In many civilian hospitals, it is customary to withhold any labor-stopping medication until cervical change is noted. These civilian hospitals also have abundant resources to treat preterm labor and premature infants should labor unexpectedly progress rapidly. In an operational setting, such resources may not be available and earlier treatment may be indicated. 
 

In military settings, it is often helpful to postpone delivery long enough to get the patient to a definitive care setting, even if the patient is more than 34 weeks gestation. It is best to coordinate the use of these medications with the receiving facility. Any of the following treatments may effectively disrupt the labor process for 24-48 hours, and this is usually long enough to move the patient to an area of greater resource.

• Magnesium sulfate, 4 gm loading dose over at least 5 minutes, followed by 2 gm/hour in a steady IV drip. Watch for magnesium toxicity with diminished reflexes and respiratory depression, and treated with calcium.
• Ritodrine (Yutapar) 100 µg/minute IV, increased every 15 minutes by 50 µg to a maximum of 350 µg/min. Titrate dosage to a maternal pulse of not less than 100 BPM and not greater than 120 BPM. Watch for pulmonary edema in the mother.
• Terbutaline 0.25 mg SQ, every 1-4 hours x 24 hours, total dose not to exceed 5 mg in 24 hours. May also be given PO in 2.5 - 7.5 mg doses, every 1.5 - 4 hours. Target maternal pulse rate is > 100 and < 120 BPM
• Indomethacin (Indocin), 50 mg PO (or 100 mg PR), followed by 25 mg PO every 4-6 hours for up to 48 hours. Watch for gastric bleeding, heartburn, nausea and asthma.
• Nifedipine, 10 -20 mg PO every 4-6 hours (Watch for headache, flushing and nausea).

While postponing delivery, many fetuses less than 34 weeks gestation will benefit from administering steroids to the mother. The effect of the steroids on the fetus is to accelerate fetal pulmonary maturity, lessening the risk of respiratory distress syndrome of the newborn. Appropriate doses include:

• Betamethasone 12 mg IM, and repeated in 24 hours.
• Dexamethasone 6 mg IM Q 12 hours x 4 doses.

When transporting the mother to a definitive care setting, have her remain wa