What are the options for inducing labour in a second gravida (second pregnancy) at 39 weeks of gestation?

Induction of Labour in a Second Gravida: Available Options

For a second gravida (multiparous woman) at 39 weeks, the available induction options include cervical ripening methods (single-balloon Foley catheter 60-80mL for 12 hours, oral misoprostol 25-50μg, or combination therapy) followed by oxytocin infusion, though it's important to note that the evidence supporting elective induction at 39 weeks specifically applies to nulliparous women and cannot be directly extrapolated to multiparous patients. 1

Critical Evidence Gap for Multiparous Women

The ARRIVE trial and subsequent SMFM guidelines explicitly state that it is unknown whether the findings can be extrapolated to multiparous women 1. All the high-quality evidence supporting elective induction at 39 weeks was conducted exclusively in low-risk nulliparous women 1. This represents a significant limitation when counseling your second gravida patient.

Available Induction Methods

Cervical Ripening Options

For cervical ripening, the recommended approach combines a 60-80mL single-balloon Foley catheter for 12 hours with either oral misoprostol or oxytocin infusion 2:

• Oral misoprostol: 25μg initially, then 25μg every 2-4 hours, OR 50μg every 4-6 hours (only if no more than 3 contractions per 10 minutes and no previous uterine surgery) 2
• Oxytocin infusion: Can be used in combination with Foley catheter 2
• Membrane stripping: Should be considered at the beginning of induction 2

Cervical Assessment

Assess cervical favorability using the modified Bishop score before selecting an induction method 3, 4:

• Bishop score ≥8: Favorable cervix - proceed with oxytocin and/or artificial rupture of membranes 4
• Bishop score <5: Unfavorable cervix - use cervical ripening agents first 3
• The Bishop score evaluates: cervical dilation (cm), effacement (%), consistency, position, and fetal station 4

Oxytocin Protocol

For oxytocin administration, start with 1-2 mU/min and gradually increase by 1-2 mU/min increments until adequate contraction pattern is established 5:

• Prepare solution: 10 units oxytocin in 1000mL non-hydrating diluent (10 mU/mL) 5
• Use infusion pump for accurate control 5
• Monitor fetal heart rate, uterine tone, and contraction frequency continuously 5
• Once 5-6 cm cervical dilation is achieved, consider discontinuing oxytocin if adequate contractions are present 2

Timing Considerations

At 39 Weeks (Your Patient)

• Elective induction at 39 weeks is reasonable for low-risk nulliparous women but lacks evidence for multiparous women 1, 6
• Both elective induction and expectant management are acceptable options when evidence exists 1
• Reliable dating with early ultrasonography (<21 weeks for certain LMP, first trimester for uncertain LMP) is imperative to avoid iatrogenic preterm delivery 1

At 41 Weeks

• Induction is recommended at 41 weeks or later regardless of parity 3, 7
• Risk of stillbirth at 41 weeks is 2-3 per 1000 deliveries 7

Important Caveats and Pitfalls

Avoid These Common Errors

• Never perform elective induction before 39 weeks 0 days - associated with adverse neonatal outcomes including respiratory morbidity 1
• Avoid misoprostol if any prior uterine surgery 3, 2
• Do not perform cesarean delivery before 15 hours of oxytocin infusion and amniotomy (if feasible), ideally wait 18-24 hours 2
• Allow at least 12 hours after cervical ripening before considering cesarean for "failed induction" 3

Contraindications to Consider

• Previous uterine surgery is a contraindication to misoprostol 3, 2
• Medical or obstetric conditions requiring earlier delivery should follow condition-specific guidelines 1

Shared Decision-Making Approach

Counsel your second gravida patient that while induction options are available, the evidence supporting benefits (reduced cesarean delivery, reduced hypertensive disorders) comes from nulliparous women only 1:

• In nulliparous women, elective induction at 39 weeks reduces cesarean delivery (18.6% vs 22.2%) 1, 6, 8
• In nulliparous women, it reduces hypertensive disorders (9.1% vs 14.1%) 1, 6
• Number needed to treat to prevent one cesarean in nulliparous women is 28 1, 6

For multiparous women, expectant management until spontaneous labor or medical indication may be more appropriate given the lack of specific evidence 1.

Resource Considerations

• Facility capacity and staffing (nurses, anesthesiologists) must be adequate 1
• Women with medical/obstetric indications take priority for induction slots 1
• Outpatient Foley ripening can be considered for low-risk women 2