ResumoOBJETIVO: avaliar os aspectos morfológicos e vasculares do corpo lúteo (CL) por parâmetros ultrassonográficos durante a gestação inicial e sua associação com o abortamento. MÉTODOS: estudo de coorte, prospectivo com 90 gestantes entre 6 e 8 semanas mais 6 dias de gestação. Foram incluídas gestantes de baixo risco, sem doença sistêmica aguda ou crônica, e com concepção espontânea. Abstract PURPOSE: the purpose of this research was to evaluate the morphological aspects and vasculature of the corpus luteum (CL) based on ultrasound parameters during early pregnancy and to assess their relationship with early pregnancy loss. METHODS: this was a prospective cohort study of 90 pregnant patients between 6 and 8 weeks plus 6 days weeks of gestation. We included women at low risk, without acute or chronic systemic disease and with spontaneous conception. Exclusion criteria: use of drugs or smoking, drugs inducing ovulation, history of more than one abortion, no heartbeat visible in the embryo and impossibility of visualization of the corpus luteum. The size, volume, morphological aspects, resistive index, and peak systolic velocity of the corpus luteum were measured by transvaginal sonography. RESULTS: ninety patients were included in the study. Maternal age ranged from 15 to 41 years (mean 28.6±5.8 years). The corpus luteum could be visualized in 87 patients (96.7%), 79 patients had normal pregnancies (90.1%), whereas spontaneous losses occurred in 8 cases (9.9%). In a comparison of the survivors and losses, there was no difference in mean CL diameter (21.8 versus 20.0 mm; p=0.108, Mann-Whitney test), mean CL volume (4.2 versus 3.0 cm 3 ; p=0.076, Mann-Whitney test), mean resistive index (0.55 versus 0,58; p=0.220, Mann-Whitney test), peak systolic velocity (15 versus 15 cm/s; p=0.757, Mann-Whitney test). There was a positive relation between maternal age and resistive index. CONCLUSIONS: no apparent correlation was found between the morphological and vascular aspects of the corpus luteum in early normal pregnancies and first-trimester pregnancy losses.