PRETERM LABOR


Regular uterine contractions + concurrent cervical change at < 37 weeks gestation

Hx / PE

  • Patients may have Menstrual-like cramps or Contractions, onset of Low back pain, Pelvic pressure, and New Vaginal DSischarge or Bleeding.

DIFFERENTIAL DIAGNOSIS
The differential should include premature labor, preterm rupture of membranes, preterm contractions (contractions prior to 37 wk gestation that do not result in cervical change), and abdominal pain or cramping secondary to other medical conditions. There are many conditions that may cause preterm contractions or premature labor. These include:

  • Infection
    • Chorioamnionitis
    • Genital tract infections, including bacterial vaginosis, gonorrhea, chlamydia
    • Urinary tract infections, including pyelonephritis, cystitis, or asymptomatic bacteruria
    • Gastroenteritis
  • Trauma
  • Placental abruption
  • Illicit drug use
  • Preterm premature rupture of membranes
  • Appendicitis
  • Nephrolithiasis
  • Pancreatitis
  • Cholelithiasis

Dx

  • Requires regular uterine contractions (≥ 3 contractions of 30 seconds each over a 30-minute period) and concurrent cervical change at < 37 weeks’ gestation.
  • Assess for contraindications to tocolysis (e.g., infection, nonreassuring fetal testing, placental abruption).

Workup

  • History and physical exam to rule out trauma, abuse, other causes of abdominal pain, and infection.
  • Fetal heart rate monitoring and tocometry to determine fetal status and contraction frequency.
  • Speculum exam to visually assess the cervix and assess for PROM, bleeding, infection, or advanced cervical dilation.
    • If the patient is , < 35 wk gestation, a Fetal Fibronectin (FFN) test should be collected prior to performing a digital exam or transvaginal ultrasound.
    • A FFN test can help predict preterm delivery if the patient has a cervical length on transvaginal ultrasound of < 30 mm.
  • Digital exam to determine cervical dilation and effacement, and fetal station.
  • LABS: CBC, Urine analysis and culture, Urine toxicology screen, Collect tests for GBS, gonorrhea, and Chlamydia, Perform a wet prep for yeast, bacterial vaginosis, and trichomonas, Fetal fibronectin, Consider PT, PTT, INR, CMP, amylase, and lipase, Amniocentesis may be performed if an intraamniotic infection is suspected.
  • IMAGING : A formal Ultrasound is indicated to determine estimated fetal weight, fetal presentation, amniotic fluid volume, placental location and appearance, and cervical length.

Treatment

  • Hydration and bed rest, Smoking cessation.
  • Deliver promptly if:  (+) Premature labor, (+) intraamniotic infection suspected or when they have cervical dilation > 5 cm, a persistently nonreassuring fetal heart rate tracing, intrauterine growth restriction, or vaginal bleeding concerning for placental abruption.
  • Unless contraindicated, begin Tocolytic therapy between 24 wk and 33 6/7 wk (β-mimetics, MgSO4, Ca2+ channel blockers, PGIs) and give Steroids to accelerate fetal lung maturation.
  • Give penicillin or ampicillin for GBS prophylaxis if preterm delivery is likely.
  • CHRONIC Rx
    • Patients with a history of prior spontaneous preterm birth may be candidates for prophylactic use of 17 alpha-hydroxyprogesterone caproate between 16 wk and 36 wk gestation.
    • Patients with a history of preterm birth and short cervix may also be candidates for prophylactic or rescue cerclage.
    • There is no evidence supporting the use of maintenance tocolytic therapy
  • REFERRAL
    • Women who present in preterm labor should be referred to an obstetrician and transferred to a facility with a neonatal intensive care unit.
    • For women who present for prenatal care with a history of preterm delivery, early referral to an obstetrician is also recommended.

Complications

  • RDS, intraventricular hemorrhage, PDA, necrotizing enterocolitis, retinopathy of prematurity, bronchopulmonary dysplasia, death.

Risk Factors

Risk factors for preterm labor
  • PIMS
  • Placental abruption/Polyhydramnios
  • Infection/Inadequate cervix
  • Multiple gestation/Multiple years (advanced maternal age)
  • Single, Sad, or Stressed/Substance abuse


Risk Category Risk Factors
Socioeconomic Single, anxiety/depression, emotional stress, poor nutrition, maternal age > 40 or < 18, substance abuse, tobacco, African-American, extreme physical exertion.
Uterine/placental Multiple gestation, polyhydramnios, uterine anomalies (especially those → uterine overdistention), cervical incompetence, placental abruption or placenta previa.
Infectious Bacteriuria/pyelonephritis, STIs, bacterial vaginosis, periodontal disease.
Fetal Congenital anomalies, growth restriction

PTL