BACKGROUND AND PURPOSE: 

• Previous RCTs indicate that nonmedically indicated induction ≥39 weeks gestation compared with expectant management  
  • Does not negatively impact outcomes and may even provide benefit, including reduced cesarean section rates  
  • Has generated positive guidance regarding acceptability of this practice in very defined circumstances (see ‘Related ObG Topics’ below)

• Unclear if results applicable to the broader US pregnant population 
• Souter et al. (AJOG, 2019) compared induction at ≥39 weeks gestation vs non-electively induced pregnancies

METHODS: 

• Retrospective cohort study 
  • Chart extraction: 21 US Hospitals
  • Singleton | Cephalic | Hospital birth at 39w0d – 42w6d  

• Exclusion criteria  
  • Previous cesarean birth |Missing key delivery data | Stillbirth |Cesarean birth without trial of labor | Fetal anomaly | Maternal complications including GDM, prepregnancy diabetes and hypertension

• Primary outcome: Cesarean birth 
  • Compared rate of cesarean birth for elective inductions at 39 weeks and 40 weeks vs on-going pregnancies in the same gestational week 

• Secondary maternal outcomes included  
  • Operative vaginal birth | Shoulder dystocia | 3rd- or 4th-degree perineal laceration | Pregnancy-related hypertension | PPH  

• Secondary newborn outcomes included  
  • Macrosomia | 5-minute Apgar <7 | Resuscitation at delivery | Intubation | Respiratory complications | NICU admission 

• Length of hospital stay also assessed  
• Statistical Analysis 
  • Logistic regression – adjusted for maternal age and body mass index, parity, gestational age  

RESULTS: 

• 55,694 births 
  • Elective inductions (≥39+0 weeks): 4,002  
  • Not electively induced (39 – 42 weeks):  51,692  

Nulliparous women undergoing elective induction at 39 weeks  

• Decreased cesarean birth rate  
  • Induction: 14.7%  
  • Expectant management: 23.2%  
  • Adjusted odds ratio (OR) 0.61 (95% CI, 0.41-0.89)

• Increased rate of operative vaginal birth 
  • Induction: 18.5%  
  • Expectant management: 10.8%  
  • aOR 1.8 (95% CI, 1.28–2.54) 

• Decreased risk of pregnancy-related hypertension  
  • Induction: 2.2%  
  • Expectant management: 7.3% 
  • aOR 0.28 (95% CI, 0.11–0.68) 

Multiparous women undergoing elective induction at 39 weeks 

• Decreased risk of pregnancy-related hypertension  
  • Induction: 0.9%  
  • Expectant management: 3.5% 
  • aOR 0.24 (95% CI, 0.15–0.38) 

Newborn outcomes 

• No significant increase with induction  

Length of hospital stay for women undergoing elective induction at 39 weeks  

• Increased time from admission to delivery for both nulliparous (1.3 hours) and multiparous women (3.4 hours) 

CONCLUSION: 

• Elective induction of labor at 39 weeks was associated with reduced cesarean rates in nulliparous women and decreased risk of pregnancy related hypertension in both nulliparous and multiparous women without increasing risk of adverse newborn outcomes  

• The authors state 

Additional assessment of the impact and outcomes of this intervention in a range of settings and the economic impact are imperative before elective induction of labor becomes offered routinely. 

Learn more – Primary Sources: 

Maternal and newborn outcomes with elective induction of labor at term 

Related ObG Topics: