Will an obstetrician (OB) schedule induction of labor if a patient is not in labor at 40 weeks of gestation?

Labor Induction at 40 Weeks Gestation

Yes, obstetricians will typically offer induction of labor when a pregnancy reaches 40-42 weeks of gestation, with many recommending induction by 41 weeks to reduce risks of perinatal mortality and morbidity. 1

Evidence-Based Rationale for Induction at 40-42 Weeks

The Society for Maternal-Fetal Medicine (SMFM) guidelines provide clear direction on induction timing based on the ARRIVE trial and other evidence:

• Expectant management beyond 40 weeks increases risks of:

  • Perinatal death (0.4 versus 3 deaths per 1000) 1
  • Stillbirth 1, 2
  • Meconium aspiration 2
  • Macrosomia (large baby) 2
  • Hypertensive disorders of pregnancy 1

• In the ARRIVE trial, women in the expectant management group were scheduled for induction by 40 weeks 5 days if no spontaneous labor, and all women were to be delivered by 42 weeks 2 days of gestation 1

Clinical Algorithm for Induction Timing

1. At 39-40 weeks:

   • Discussion of options with patient
   • Elective induction may be offered to low-risk nulliparous women as early as 39 weeks 1

2. At 40-41 weeks:

   • Induction typically offered/recommended
   • Benefits include reduced risk of cesarean delivery (18.6% vs 22.2%) 1
   • Reduced risk of hypertensive disorders (9.1% vs 14.1%) 1

3. By 42 weeks:

   • Induction strongly recommended due to significantly increased risks 2, 3
   • FDA labeling for oxytocin supports induction when "delivery is in the best interest of mother and fetus" 4

Important Considerations

• Cervical readiness: Even with an unfavorable cervix (Bishop score <5), induction at 39+ weeks has been shown to be safe and effective 1

• Medical indications: Induction is clearly indicated for conditions such as:

  • Rh problems
  • Maternal diabetes
  • Pre-eclampsia
  • Premature rupture of membranes 4

• Patient discomfort: Some induction methods like membrane sweeping can cause significant discomfort, with 70% of women reporting discomfort and 1/3 reporting significant pain 5

Key Points to Remember

• The ARRIVE trial showed that elective induction at 39 weeks in low-risk nulliparous women resulted in lower rates of cesarean delivery compared to expectant management 1

• High-quality evidence shows reduced perinatal mortality with induction at or beyond 41 weeks compared to expectant management 2, 3

• Oxytocin is indicated for "initiation of labor in patients with a medical indication" including when delivery is in the best interest of mother and fetus 4

• Recent evidence challenges the historical belief that induction increases cesarean delivery risk; when compared to expectant management (rather than spontaneous labor), induction does not increase adverse outcomes 6