Miscarriage treatment-related adverse events: A nationwide registry study from Finland.

Introduction: The treatment of miscarriage has transformed substantially from surgical to non-surgical. The aim of this study was to evaluate the rates of adverse events related to the treatment of miscarriage and their risk factors.

Material and methods: This nationwide retrospective cohort study included 69 593 fertile-aged (15-49 years) women who experienced their first miscarriage during 1998-2016 and received a diagnostic code of missed abortion or blighted ovum in a public hospital. We used data from the Finnish National Hospital Discharge Registry (NHDR). Miscarriage type, treatment modalities, and treatment-related adverse events (secondary surgery for any reason, infection and severe adverse events) were identified using diagnostic and surgical procedure codes.

Results: Since 2004, non-surgical management has been the dominant treatment of miscarriage in Finland. Between 1998 and 2016, a total of 11 397 women (16.4%) experienced at least one miscarriage treatment-related adverse event. The need for secondary surgery was the most common adverse event and more common after primary non-surgical treatment (22.0% vs. 3.8%). However, the annual rate of secondary surgery after non-surgical treatment declined from 34.8% in 1998 to 15.9% in 2016. The total number of women undergoing surgical treatment (primary or secondary) declined from 3918 (84.6%) to 651 (23.1%). Age was associated with an increased risk of secondary surgery (age ≥ 25; Adjusted odds ratio [AdjOR] 1.15, 95% CI 1.07-1.24) and with a decreased overall risk of infection (age 40-49 years; AdjOR 0.51 [0.40-0.63]). Parity was associated with lower risk of secondary surgery (one delivery, AdjOR 0.82 [0.78-0.95], and ≥2 deliveries, AdjOR 0.75, [0.71-0.84]) and infection (one delivery, AdjOR 0.85, [0.77-0.95]; ≥2 deliveries, AdjOR 0.74 [0.66-0.84]). Severe adverse events were rare (0.2%-0.4%) and did not differ between the two treatment options for either type of miscarriage.

Conclusions: Despite significant changes in miscarriage treatment practices, no substantial or alarming increase in treatment-associated adverse events was detected. Both treatment options proved safe for the two types of miscarriage studied. These findings are important regarding the provision of individualized counseling and for the allocation of healthcare resources.