The rates of spontaneous abortion declined: a retrospective cohort study from an industrialized area in Italy, 1996-2010

Background: Spontaneous abortions (SA) were analyzed in an industrialized Italian region over a 15-year period to evaluatetime trends. Retrospective cohort study. Methods: Since 1991, in Lombardy a standard form has been used to register all discharges from public or private hospitals. This study analyzed the Lombardy Region registry of hospital admissions in 1996\u20132010. Using the hospital discharge register, SA-related crude admission rates per 100 pregnancies in women aged 15 to 50 years, residing in Lombardy, were computed;age- and nationality-adjusted rates were also calculated. SA cases were identified searching the database for the ICD-9 codes for SA. SA rates/100 pregnancies (livebirths+SAs+induced abortions/2) in strata of age and calendar year were computed. Poissonregression analysis was used to test trends over time. Results: The crude SA rate was 10.72/100 pregnancies in 1996 and 10.45 in 2010. The corresponding age-standardized rate was 9.21. SA frequency was 4-5 times higher in women aged 40 years in comparison to women aged < 20 years. Age-adjusted SA rates decreased, over time, in non native Italian women. Conclusions: In this population, living in an industrialized area, SA frequency/100 pregnancies has slightly declined during the last 15 years