National register data are of value in studies on miscarriage-Validation of the healthcare register data in Finland.

Introduction: Despite the high prevalence of miscarriages, they are not systematically registered and few epidemiological studies have been done. As Finnish health registries are comprehensive and widely used in research, we validated the Finnish register data concerning diagnostics and treatment of miscarriage, and treatment-related adverse events.

Material And Methods: We conducted a validation study regarding miscarriage-related codes of diagnoses and surgical procedures in a Finnish National Hospital Discharge Registry (NHDR) by comparing the information from the NHDR with that of the hospital records.

Trends in the incidence, rate and treatment of miscarriage-nationwide register-study in Finland, 1998-2016.

Study Question: What changes have occurred in the incidence of miscarriage, its treatment options, and the profile of the women having miscarriages in Finland between 1998 and 2016?

Summary Answer: The annual incidence of registry-identified miscarriage has declined significantly between 1998 and 2016, and non-surgical management has become the dominant treatment.

What Is Known Already: Miscarriage occurs in 8-15% of clinically recognized pregnancies and in ~30% of all pregnancies. Increasing maternal age is associated with an increasing risk of miscarriage.