Trends of Spontaneous Abortions in Italy 1990–1995

To the Editor: Rates of spontaneous abortion increased in Italy from 6.3/100 pregnancies in 1980 to 7.6 in 1991. The increase was generally constant during the period and was similar across subsequent age strata, with the exception of teenagers and of women age 50 or more. 1 We have now updated trends in rates of spontaneous abortion to 1995, using data published annually by the Italian National Institute of Statistics (ISTAT). 2,3 In Italy, spontaneous abortion is defined by law as a termination of pregnancy 180 days or less after the last menstrual period. The spontaneous abortion rate has been calculated using the number of spontaneous abortions (SA) as numerator and the total number of pregnancies (ie, the simple sum of spontaneous and induced abortions (IA) plus births (LB)) as denominator. Rates according to maternal age have been also analyzed using direct standardization for maternal age, taking the Italian population of 1982 as reference. 4 Because spontaneous abortion and induced abortion are competing risks, we have also analyzed the data using the statistic: SA/(SA+LB+IA/2). 5 Overall, age-adjusted rates of spontaneous abortion increased from 7.3 in 1992 to 8.3/100 pregnancies in 1995 with 95% confidence intervals of 7.2–7.5 and 8.2–8.4, respectively (Table 1).Similar trends also emerged after considering the competitive role of induced abortion. The increase in the rate of spontaneous abortion was larger in very young (<15 year, from 21.2 to 31.1/100 pregnancies, in 1992 and 1995, respectively) and older (≥50 years from 36.8 to 40.4/100 pregnancies) women, but we also found some increased risk in the intermediate age groups (Table 2).These trends in spontaneous abortions can be explained by improved diagnosis, following a wider availability of transvaginal ultrasounds, but this explanation cannot account for the different trends in various strata of age. It is also likely that the criteria for definition at certification of spontaneous abortion have changed in clinical practice over the last few years. We have not considered ectopic pregnancies, but this omission should not have introduced any marked bias. Table 1: Trends of Crude and Standardized for Age Rate of Spontaneous Abortion in Italy, 1982, 1990–1995Table 2: Trends of Spontaneous Abortion (Rates per 100 Pregnancies) According to Maternal Age (Italy, Selected Years)An increased frequency of abortion has been observed in pregnancies after assisted reproduction 6 and also after amniocentesis performed in the first trimester of pregnancy. 7 These effects could explain the increased rates of spontaneous abortion in women 35 years of age or older, but not in younger women. Whereas the rate of pregnancy (ie, the number of SA plus IA and births on number of women) for very young girls (<15 years) remained stable from 1981 to 1995, spontaneous and induced abortions had an inverse trend. 8 This pattern could be explained by a greater attention on sex education of teenagers in the 1990s, with a rise of wanted pregnancies and a simultaneous diminution of IA. These trends could have affected the rate of SA, resulting in an increase of the proportion of IA that could potentially end in SA. Cristina Rozzi Luigi Benassi Fabio Parazzini Liliane Chatenoud Carlo La Vecchia Guido Benzi