Are there features of SCH associated with an increased risk of miscarriage?

Subchorionic haematomas (SCH) are defined as a collection of blood between the chorion and endometrium1.  They are common (reported incidence between 0.46 and 39.5% of pregnancies) and are associated with an increased rate of miscarriage2. There has also been some debate around the link betweenSCH and adverse pregnancyoutcomes such as abruption and preterm labour3.