Grand Rounds

Vaginal Delivery of Twin A and Cesarean Delivery for Twin B: Risk Factors and Outcomes

BACKGROUND AND PURPOSE:

Aviram et al. (AJOG, 2019) determined the incidence, risk factors, and outcomes for combined twin deliveries (Twin A: vaginal | Twin B: Cesarean)

Secondary analysis of a prospective, randomized, controlled trial
- Data derived from the Twin Birth Study (TBS) RCT that compared planned vaginal delivery to planned combined delivery in twin pregnancies
Participants
- Twin gestation
- Between 32w0d and 38w6d
- First twin vertex
Groups
- Planned cesarean delivery
- Planned vaginal delivery
Study design and data analysis
- Comparison of women with combined vs vaginal delivery of both twins
Primary outcome
- Risk factors for combined twin deliveries
Secondary outcomes
- Rate of perinatal mortality and morbidity

842 women delivered twin A vaginally
- Combined delivery: 7%
Women in the combined delivery group had
- A lower rate of nulliparity (P = 0.047)
  - 22.0% vs 34.7%
- Twin B: Higher rates of noncephalic presentation at delivery (P < 0.001)
  - 61.0% vs 27.3%
- Twin B: Higher rates of spontaneous change in presentation from the time of randomization to the time of delivery (P < 0.0001)
  - 72.9% vs 44.3%
Transverse/oblique lie of twin B following delivery of twin A was associated with risk of combined delivery
- Adjusted odds ratio (OR) 47.7 (95% CI, 15.4 to 124.5)
Comparing the combined delivery group to the group where both twins delivered vaginally, the frequency of adverse events in Twin B was significantly increased
- Fetal/neonatal death or serious neonatal morbidity
  - 13.6% vs 2.3% (P<0.001)
- 5-minute Apgar score <7
  - 20.7% vs 2.1% (P<0.001)
- NICU admission ≥48 hours
  - 12.07% vs 5.27% (P<0.001)
- Abnormal level of consciousness (coma)
  - Coma 1.72% vs 0% (P =0.02)
- Assisted ventilation ≥24 hours
  - 5.17% vs 0.90% (P<0.001)

This study confirmed increased risk for combined delivery for twin B (e.g. mortality, morbidity, NICU admission, etc.)
The only risk factor for combined delivery following adjustment for confounding was transverse/oblique lie (not breech) of twin B following vaginal delivery of twin A
There was no association between adverse outcome in twin B and initial presentation of twin B or with inter-twin delivery interval
The authors suggest these results may have clinical implications including a discussion regarding “the policy of routine ‘double set-up’ for twin deliveries in the operating room, as a way to decrease the decision-to-incision interval”
Authors acknowledge limitations including the fact that the original TBS study was not powered for this study’s subanalysis

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