BACKGROUND AND PURPOSE:

• Up to 75% of preterm birth is spontaneous (SPTB) while remainder are indicated (IPTB) deliveries, based on maternal or fetal complications
• Public health policy may suggest focusing resources on the more common SPTB cohort, but there is limited data as to which group has the burden of adverse events
• Tita et al. (American Journal of Perinatology, 2018) compared the risks of adverse maternal and neonatal outcomes associated SPTB vs IPTB

METHODS:

• Retrospective Cohort Study
  • Secondary analysis of multicenter trial including women with SPTB and IPTB
  • Original study: NICHD RCT of vitamin C and E to prevent preeclampsia in low risk nulliparous patients
• Primary exposure: PTB (<37w0d) – SPTB vs IPTB
• Primary maternal outcome: Composite of the following
  • Death |Pulmonary edema |Blood transfusion | ARDS | Cerebrovascular accident | ATN | DIC | Liver rupture
• Primary neonatal outcome: Composite of the following
  • Neonatal death | RDS | Grades III or IV IVH |Sepsis | NEC | ROP

RESULTS:

• 9,867 women were included in the study
  • 1,038 women underwent preterm births
  • 340 IPTBs
  • 698 SPTBs

Maternal Adverse Events

• Composite maternal outcome was more frequent in IPTB (4.4%) vs SPTB (0.9%)
  • adjusted odds ratio [aOR], 4.0 (95% CI, 1.4–11.8)
• Blood transfusion was more common in IPTB (3.4%) vs SPTB (0.9%); P=0.005
  • aOR 3.2 (95% CI, 1.1-9.8)
• Prolonged hospital stay was more frequent in ITPB (8.7%) vs SPTB (1.8%); P<0.001
  • aOR 3.7 (95% CI, 1.8-7.7)

Newborn Adverse Events

• Composite neonatal outcome was less frequent in IPTB (22.6%) vs SPTB (24.1%) but when adjusted for confounders inlcuding demographics and peripartum infections, risk increased
  • aOR, 1.8 (95% CI, 1.1–3.0)
• Other outcomes that were increased in IPTB vs STB group
  • RDS: aOR 1.7 (95% CI, 1.1-2.7)
  • SGA <5th percentile: aOR 7.9 (95% CI, 4.0-15.7)
  • NICU admission: aOR 1.8 (95% CI, 1.3-2.5)
• Crude risk of death higher in SPTB
• Most frequent reason for IPTB was pregnancy-associated hypertension
  • Outcomes for this indication only were similar to the overall group, except that neonatal composite and RDS were no longer statistically different

CONCLUSION:

• IPTB vs SPTB have a fourfold higher incidence of maternal adverse events
• The authors state that based on the results of this study “interventions to prevent the underlying causes of IPTBs such as preeclampsia, to reduce the risk of IPTBs and hence reduce the associated burden of adverse outcomes may deserve as much attention as directed toward SPTBs”

Learn More – Primary Sources:

Adverse Maternal and Neonatal Outcomes in Indicated Compared with Spontaneous Preterm Birth in Healthy Nulliparas: A Secondary Analysis of a Randomized Trial

Related ObG Topics:

Antenatal Corticosteroids – When to Administer?

Are Vitamin D Levels Linked to Preeclampsia and Preterm Birth?

Progesterone or Cerclage in Preterm Prevention in Women with Previous Preterm Birth and Short Cervix?