VP22.20: Comparison of perinatal outcomes in triplet pregnancies: spontaneous versus elective preterm birth

To compare obstetric and perinatal outcomes between spontaneous and elective preterm births in triplet pregnancies. This study comprised a prospective pregnancy cohort of women who had confirmed triplet pregnancies on antenatal ultrasound scans at 7-14 weeks gestation uploaded as fully digitalised medical records at a tertiary academic teaching hospital from 2007 to 2020. Perinatal outcomes (≧ 22 weeks gestation to the first 28 days of life), antenatal characteristics, obstetric outcomes and neonatal morbidity were evaluated after exclusion of major anomalous cases and compared between spontaneous (spontaneous labour onset, SPTB) and elective preterm births (medically indicated or iatrogenic due to maternal burden). Generalised estimating equations were adapted for association of binary outcome data with clustering of triplet pregnancy' outcomes and their effect on neonatal outcomes. Out of 394 triplet pregnancies, the SPTB group (n = 135) had 21 perinatal deaths (21/398, 5.3%), 4 in utero and 17 at neonate, significantly higher than elective group (6/772, 0.8%, P〈0.001). Overall rate of composite neonatal morbidity was 28.6% (110/384) in SPTB vs. 2.9% (22/764) in the elective group (P〈0.001). SPTB was associated with significantly increased risk of composite morbidity compared with elective group (risk ratio [RR] = 11.9, 10.9-13.1). The effect of spontaneous labour on neonatal morbidities in order of magnitude is: intraventricular hemorrhage (RR = 7.1E+10) – independently from mode of delivery, culture-proven sepsis (RR = 50.3) and retinopathy of prematurity (RR = 30.9) (all P〈0.001). Subgroup analysis limited to delivery after 32 weeks of gestation was done (SPTB = 97, elective = 253). SPTB group (6.8%, 30/284) showed a higher rate of composite morbidity than the elective group (21/757, 2.8%, P〈0.001) (RR = 3.7, 2.5-5.6). Spontaneous onset of preterm labour was associated with significantly increased neonatal morbidity in triplet pregnancies and its effects on triplets warrant further research to better understand its clinical consequences.