COVID-19 and first trimester spontaneous abortion: a case-control study of 225 pregnant patients

Cosma, S.; Carosso, A.; Cusato, J.; Borella, F.; Carosso, M.; Bovetti, M.; Filippini, C.; D'Avolio, A.; Ghisetti, V.; Di Perri, G.; Benedetto, C.

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 as a risk factor for spontaneous abortion 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 (case group, n=100) and those with ongoing pregnancy (control group, n=125). Current or past infection was determined by detection of SARS-CoV-2 from nasopharingeal swab and SARS-CoV-2 IgG/IgM antibodies in blood 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. 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 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.