Perinatal outcome of dichorionic and monochorionic‐diamniotic Finnish twins: a historical cohort study

Abstract

Introduction Although the perinatal mortality of monochorionic twins has been reported to be higher, the role of chorionicity is debated and data from Finland are still lacking. To examine the effect of chorionicity on the main outcome measures, perinatal and neonatal mortality and neonatal morbidity of Finnish twins, a comprehensive population‐based historical cohort study was performed at Helsinki University Hospitals. Material and methods All 1034 dichorionic and monochorionic‐diamniotic twin pregnancies managed at Helsinki University Hospital area during 2006, 2010, 2014 and 2018 were collected from patient databases. Information on chorionicity was retrieved from ultrasound reports and all relevant clinical information from patient records. Differences in perinatal and neonatal mortality and neonatal morbidity were analyzed by performing group comparisons between the twins and chorionicity. The role of chorionicity was also assessed in logistic regression analyses. Results There were 1034 dichorionic‐diamniotic (DCDA, n = 789, 76.3%, 95% confidence interval [CI] 73.6–78.9) and monochorionic‐diamniotic (MCDA, n = 245, 23.7%, 95% CI 21.4–26.0) twin pregnancies during the studied years. Most (n = 580, 56.1%, 95% CI 52.8–59.2) twins were born at term, but 151 (61.6%, 95% CI 55.8–67.3) of MCDA twins were preterm and had lower birthweight and Apgar scores and higher risk of death of one twin. Perinatal and neonatal mortality did not differ between twins A and B, but the immediate outcome of twin B was worse, with lower arterial pH and Apgar scores and increased need of neonatal intensive care unit treatment. Conclusions Chorionicity contributes to the perinatal and neonatal outcome in favor of dichorionic twins. This disadvantage of MCDA twinning is likely explained by earlier gestational age at birth and inequal placental sharing. Irrespective of chorionicity, twin B faces more complications.

Mode of delivery of Finnish dichorionic and monochorionic‐diamniotic twins: A retrospective observational study including a risk score for intrapartum cesarean birth

“…Yet, the perinatal mortality of twins is low in Finland. 17 , 31 With twin A in breech, careful consideration is, however, required as CD is commonly recommended. 25 , 26 Even though the numbers are small, our results for breech presenting twin A add to the little existing data.…”

“…These results implicate satisfactory patient selection for twin VD, even if the first twin is breech, but selection bias is also a limitation of the study as 65.8% of breech‐presenting twins A were preterm and 71.1% of these parturients were multiparous. Yet, the perinatal mortality of twins is low in Finland 17,31 . With twin A in breech, careful consideration is, however, required as CD is commonly recommended 25,26 .…”

“… 15 , 16 Although spontaneous prematurity is common, induction of labor is also often needed before term and depending on chorionicity. 2 , 4 , 17 , 18 Overall, the magnitude of the risk of intrapartum CD after induction of labor among twins is debated. 19 , 20 , 21 …”

“…15,16 Although spontaneous prematurity is common, induction of labor is also often needed before term and depending on chorionicity. 2,4,17,18 Overall, the magnitude of the risk of intrapartum CD after induction of labor among twins is debated. [19][20][21] At the time of delivery over half of both twins are in cephalic presentation, yet up to 12% of vertex second twin experience intrapartum presentation change.…”

“…Nulliparity and noncephalic second twin have been identified as potential risk factors for intrapartum CD, but the role of maternal age or ART is less clear 15,16 . Although spontaneous prematurity is common, induction of labor is also often needed before term and depending on chorionicity 2,4,17,18 . Overall, the magnitude of the risk of intrapartum CD after induction of labor among twins is debated 19–21 …”