She became pregnant and had a son. Judah named him Er.
Referenced Verses
Gen 46:12 : 12 The sons of Judah: Er, Onan, Shelah, Perez, and Zerah(but Er and Onan died in the land of Canaan). The sons of Perez were Hezron and Hamul.
Num 26:19 : 19 Judah The descendants of Judah were Er and Onan, but Er and Onan died in the land of Canaan.