Perinatal outcomes in TOL and PCS groups
Table 3 lists the incidence of adverse perinatal outcomes as well as the association between perinatal factors for fetuses born in each group. The composite perinatal morbidity was observed in 3.6% of pregnancies (3/84) in at least one fetus in the TOL group, and in 8.3% of pregnancies (5/60) in the PCS group [aOR 1.36 (95% CI 0.24-7.81), p=0.22]. The rate of composite perinatal morbidity was higher in the PCS group for the second twin [5.0% vs. 2.4%, aOR 3.20 (95% CI 0.16-65.88)], yet these differences did not reach statistical significance (p=0.16). None of the eight cases in which breech extraction was performed had a perinatal complication.
Composite perinatal morbidity declined significantly after 32 weeks of gestation, remaining under 20% until 37 weeks (figure 2). Due to the low frequency of the different items included in terms of composite perinatal morbidity, we did not find significant differences between the two groups in any of them. No cases resulted in neonatal death in either group.
In the subgroup analysis, we compared the outcomes regarding the onset of labor when a vaginal delivery was attempted (table 4). The mean gestational age was significantly lower in the spontaneous delivery group, since no labor induction was performed by protocol below 35 weeks (35.4 vs. 36.6 weeks, p=0.001). Within the TOL group, the rate of composite perinatal morbidity was higher in the spontaneous trial of labor subgroup (8.3% vs. 0%, p=0.08), essentially related to an IVH event occurred in both twins born from the same delivery at 34.2 weeks.
Finally, we performed a comparison between the perinatal outcomes of induced onset of labor group vs. PCS group (table 5). We found a higher composite perinatal morbidity in the PCS group, although without significant differences (8.3% vs. 0%, p=0.06). These differences were maintained in the stratification by gestational age and order of birth.