No, it is not usual or common to have a brown vaginal discharge in week 3 of pregnancy. At this time, the woman may have more abundant whitish discharge, but it is rare to have brown discharge.
Read the full article on: 3 weeks pregnant – the start of the development of the embryo ( 36).
Read the full article on: Increased vaginal discharge during pregnancy ( 73).

Marta Barranquero Gómez
B.Sc., M.Sc.
Graduated in Biochemistry and Biomedical Sciences by the University of Valencia (UV) and specialized in Assisted Reproduction by the University of Alcalá de Henares (UAH) in collaboration with Ginefiv and in Clinical Genetics by the University of Alcalá de Henares (UAH).
License: 3316-CV