Anti-NMDA-R encephalitis has been described as a cause of acute psychosis in young females. It is rare during pregnancy. We describe a primigravida 32-year-old woman with acute onset psychosis during the first trimester. Eight weeks after becoming pregnant, the patient became psychotic with associated catatonia and autonomic disturbance. Serum anti-NMDA-R antibodies were found. She responded to plasma exchange. At caesarean section, a healthy baby boy was born and a benign mature cystic teratoma was removed from the left ovary. Catatonia associated with psychosis may occur in pregnancy secondary to anti-NMDA-R encephalitis. Prompt and aggressive treatment can lead to a good outcome for both baby and mother.