BACKGROUND AND PURPOSE:

• The current SMFM guideline recommends
  • 250 mg 17-OHPC IM weekly starting at 16-20 weeks of gestation until 36 weeks of gestation or delivery
• Ning et al. (AJOG, 2017) examined the relationship between the gestational age at 17-OHPC initiation in women with prior preterm birth

 METHODS:

• Retrospective cohort study
• Women included were those who had ≥ 1 previous spontaneous preterm birth between 16 and 28 weeks with one of the following:
  • Spontaneous onset of contractions
  • Preterm PROM
  • Painless cervical dilation
• Women were grouped based on quartiles of gestational age of initiation
  • Early-Start: Quartile 1 (140/7 to 161/7) + Quartile 2 (162/7 to 170/7)
  • Late-Start: Quartile 3 (171/7 to 186/7) + Quartile 4 (190/7 to 275/7)
• Primary Outcomes:
  • Recurrent preterm birth <37 weeks’ gestation
• Secondary outcomes:
  • Recurrent preterm birth <34 and <28 weeks’ gestation
  • Composite major neonatal morbidity (diagnosis of grade III or IV intraventricular hemorrhage, periventricular leukomalacia, bronchopulmonary dysplasia, necrotizing enterocolitis stage II or III, or death)

 RESULTS:

• 132 women met inclusion criteria
• 39% delivered < 37 weeks
• 17-OHPC was initiated at a mean 17 weeks 5 days ± 2.5 weeks
• Women with Early-Start trended toward lower rates of recurrent preterm birth <37 weeks compared to Late-Start (41.3% compared to 57.7%, P= 0.65) but not statistically significant
• Women with Early-Start had a later mean delivery gestational age (37.0 ± 3.1 weeks vs 35.0 ± 5.1 weeks for women with late-start 17-OHPC [P = .008])
• In regression models, odds of preterm birth were increased based on
  • Later Initiation Quartile
  • Short cervical length (<25 mm) in the midtrimester
  • Prepregnancy BMI ≥30 kg/m2
• Delivery gestational age was inversely proportional to gestational age at initiation
  • quartile 1, 37 weeks 4 days vs quartile 2, 36 weeks 5 days vs quartile 3, 36 weeks 1 day vs quartile 4, 34 weeks 0 days; P = .007
• Early-Start had lower rates of major neonatal morbidity compared to Late-Start  (1.5% vs 14.3%, P = .005)

 CONCLUSION:

• Rates of recurrent preterm birth among women with a prior spontaneous preterm birth 16-28 weeks are high
• Women beginning 17-OHPC earlier deliver later and have improved neonatal outcomes
• Authors recommend initiation at 16 weeks and to study whether even earlier initiation may be appropriate for higher risk patients

 Learn More – Primary Sources:

Gestational age at initiation of 17-alpha hydroxyprogesterone caproate and recurrent preterm birth

Related ObG Topics:

Preventing Preterm Birth in Twins – What works?

SMFM Statement: Choice of Progestogen for Preterm Birth Prevention