Background Evidence for the impact of COVID-19 during the second and the third trimester of pregnancy is limited to a relatively small series, while data on the first trimester are scant. With this study we evaluated COVID-19 infection MESHD infection as a risk TRANS infection as a risk TRANS as a risk factor for spontaneous abortion MESHD spontaneous abortion HP in first trimester of pregnancy. Methods Between February 22 and May 21, 2020, we conducted a case-control study at S. Anna hospital, Torino, among first trimester pregnant women, paired for last menstruation. The cumulative incidence of COVID-19 was compared between women with spontaneous abortion MESHD spontaneous abortion HP (case group, n=100) and those with ongoing pregnancy (control group, n=125). Current or past infection MESHD was determined by detection of SARS-CoV-2 from nasopharingeal swab and SARS-CoV-2 IgG/IgM antibodies SERO in blood SERO sample. Patient demographics, COVID-19-related symptoms, and the main risk factors for abortion were collected. Findings Twenty-three (10.2%) of the 225 women tested positive for COVID-19 infection MESHD. There was no difference in the cumulative incidence of COVID-19 between the cases (11/100, 11%) and the controls (12/125, 9.6%) (p=0.73). Logistic regression analysis confirmed that COVID-19 was not an independent predictor of abortion (1.28 confidence interval 0.53-3.08). Interpretation COVID-19 infection MESHD during the first trimester of pregnancy does not appear to predispose to abortion; its cumulative incidence did not differ from that of women with ongoing pregnancy.