Preterm Labor

UpToDate:

- Diagnosis: persistent uterine contractions (4 every 20 minutes or 8 every 60 minutes) with documented cervical change or cervical effacement ≥80 percent or cervical dilation >2 cm.

- After an observation period of four to six hours, women without progressive cervical dilation and effacement are discharged to home, as long as fetal well-being is confirmed (eg, reactive nonstress test) and obstetrical complications associated with preterm labor, such as abruptio placenta, chorioamnionitis, and preterm rupture of membranes, have been excluded. We arrange follow-up in one to two weeks and give the patient instructions to call if she experiences additional signs or symptoms of preterm labor, or has other pregnancy concerns (eg, bleeding, rupture of membranes, decreased fetal activity).

- <34 weeks with uterine contractions, cervical dilation ≥3 cm supports the diagnosis of preterm labor; further diagnostic evaluation with sonographic measurement of cervical length or laboratory assessment of fetal fibronectin does not enhance diagnostic accuracy. Treatment of preterm labor is initiated.

ACOG PB 127:

Level A:

- A single course of corticosteroids is recommended for pregnant women between 24 weeks of gestation and 34 weeks (now up to 37 weeks) of gestation who are at risk of preterm delivery within 7 days.

- two 12-mg doses of betamethasone given intramuscularly 24 hours apart or four 6-mg doses of dexamethasone every 12 hours administered intramuscularly.

- Accumulated available evidence suggests that magnesium sulfate reduces the severity and risk of cerebral palsy in surviving infants if administered when birth is anticipated before 32 weeks of gestation.

- The evidence supports the use of first-line tocolytic treatment with beta-adrenergic agonist therapy, calcium channel blockers, or NSAIDs for short-term prolongation of pregnancy (up to 48 hours) to allow for the administration of antenatal steroids.

- Maintenance therapy with tocolytics is ineffective for preventing preterm birth and improving neonatal outcomes and is not recommended for this purpose.

- Antibiotics should not be used to prolong gestation or improve neonatal outcomes in women with preterm labor and intact membranes.

Level B:

- A single course of repeat antenatal corticosteroids should be considered in women whose prior course of antenatal corticosteroids was administered at least 7 days previously and who remain at risk of preterm birth before 34 weeks of gestation.

- Bed rest and hydration have not been shown to be effective for the prevention of preterm birth and should not be routinely recommended.

- The positive predictive value of a positive fetal fibronectin test result (b/t 22 0/7 and 34 6/7)or a short cervix alone is poor and should not be used exclusively to direct management in the setting of acute symptoms.

S/p cerclage with Dr. Lawrence: Sulindac 200mg BID for 7 days.

Cervical Length:

*SMFM and ACOG PB 130 and 142.

Screening

- Recommended: routine TVUS CL screening for women with singleton pregnancy and history of prior spontaneous preterm birth.

- Reasonable but not mandatory: TVUS CL screening in women without history of preterm birth.

*From ACOOG conference: some experts recommend trans-abdominal CL screening in all women at 20 week anatomy scan:

- If less than 35mm, then perform TVUS for CL, and follow recommendations below for treatment options.

Treatment

- Offer progesterone supplementation at 16-24 weeks of gestation to a woman with history of singleton spontaneous preterm birth regardless of TVUS CL.

- Consider vaginal progesterone if TVUS CL is 20mm or less at or before 24 weeks of gestation in a woman without a history of preterm birth.

- Consider cerclage if TVUS CL is less than 25mm before 24 weeks of gestation in a woman with a history of preterm birth before 34 weeks of gestation.