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. 2022 Jan;101(1):153-162.
doi: 10.1111/aogs.14285. Epub 2021 Nov 15.

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

Annu-Riikka S Rissanen  1   2 , Mika Gissler  3   4 , Irmeli K Nupponen  5 , Mika E Nuutila  6 , Riina M Jernman  6
Affiliations

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

Annu-Riikka S Rissanen et al. Acta Obstet Gynecol Scand. 2022 Jan.

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.

Keywords: chorionicity; neonatal; perinatal mortality; pregnancy; twins.

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Conflict of interest statement

None.

Figures

FIGURE 1
FIGURE 1
Flow‐chart of the study with included and excluded cases described. DCDA, dichorionic‐diamniotic; MCDA, monochorionic‐diamniotic
FIGURE 2
FIGURE 2
(A) Annual perinatal mortality rate (PNM) of Finnish dichorionic‐diamniotic (DCDA) and monochorionic‐diamniotic (MCDA) twins per 1000 children born, reported for 2006, 2010, 2014 and 2018. (B) Annual early neonatal mortality rate (NNM; death within the first week of life) of Finnish dichorionic‐diamniotic (DCDA) and monochorionic‐diamniotic (MCDA) twins per 1000 children born alive, reported for 2006, 2010, 2014 and 2018. (C) Annual neonatal mortality rate (NNM; death in the neonatal period) of Finnish dichorionic‐diamniotic (DCDA) and monochorionic‐diamniotic (MCDA) twins per 1000 children born alive, reported for 2006, 2010, 2014 and 2018
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