Placental abnormalities differ between small for gestational age fetuses in dichorionic twin and singleton...

Area of Science:

• Perinatology
• Fetal Medicine
• Pathology

Background:

• Fetal growth restriction (FGR) is a significant concern in singleton pregnancies.
• Twin fetuses often exhibit slower growth in the third trimester compared to singletons.
• The placental factors contributing to FGR in twins are not fully understood.

Purpose of the Study:

• To investigate placental differences between small for gestational age (SGA) twins and SGA singletons.
• To determine if placenta-mediated factors in SGA twins resemble those in SGA singletons.

Main Methods:

• Retrospective cohort study of SGA newborns (birth weight <10th percentile) from singleton and dichorionic twin pregnancies (2002-2015).
• Placental findings were analyzed and classified into categories: maternal vascular malperfusion, fetal vascular malperfusion, hemorrhage, and villitis.
• Comparison of placental characteristics between SGA twins and SGA singletons.

Main Results:

• SGA twins had higher mean placental weight and lower fetal-placental ratio than SGA singletons.
• SGA twins were less likely to exhibit placental pathology, including maternal or fetal vascular malperfusion, compared to SGA singletons.
• SGA twins showed a significantly higher incidence of marginal or velamentous cord insertion.

Conclusions:

• The mechanisms driving reduced fetal growth in dichorionic twins differ from those in singletons.
• Placental findings suggest that FGR in dichorionic twins may be a more benign condition than in singletons.