When evaluating a patient with acute altered mental status or psychosis, the primary goal is to differentiate between an encephalopathy and a psychiatric disorder; such as schizophrenia or bipolar disorder. 
It is very unlikely for a first psychotic episode of a psychiatric disorder to occur during pregnancy.[ 3] A new-onset of psychosis in a pregnant woman should stimulate a thorough workup for an underlying medical or pharmacologic etiology, particularly when it is accompanied by clear disorientation, visual or tactile hallucinations, fluctuations in the level of consciousness, or evident neurologic symptoms. 
Whereas psychotic episodes of psychiatric disorders present with delusions, hallucinations, thought disorganization, and agitation. 
There is limited data on the incidence of new-onset psychotic episodes during pregnancy. According to Paffenbarger et al., the overall rate of mental illness during pregnancy was 5 per 10.000 live births. 
However, psychotic episodes of underlying psychiatric disease may relapse or reactivate during pregnancy. [2, 3]
Psychosis can be the presenting symptom of many medical illnesses and neurologic conditions, such as delirium, endocrine disorders (thyroid and adrenal dysfunction), hepatic and uremic encephalopathy, infectious disease, inflammatory and demyelinating disorders, metabolic disorders, neurological and neurodegenerative diseases, and vitamin deficiency.
Our patient had no history of endocrine, renal, or hepatic disease and her liver, and renal function tests were normal at the current presentation. She had no history of alcohol abuse and she had no diagnosed psychiatric disease.
However, she had a history of HSV encephalitis six weeks earlier and was treated with acyclovir until complete resolution. Based upon her current symptoms and history, it was presumed that she was either undergoing a recurrence of the viral encephalitis or an autoimmune encephalitis following the viral disease.
Her CSF sample analysis confirmed the latter and HSV-induced anti-NMDAr encephalitis was diagnosed.
To our knowledge, this is the first reported case in Syria of anti-NMDAr encephalitis following HSV infection in a pregnant patient.
Anti-NMDAr encephalitis is rarely reported in pregnancy and when it occurs, it is difficult to delineate it from other neuropsychiatric disorders.
Rare disorders as such can only be diagnosed when thought of; therefore we highlight the importance of taking a detailed patient history when evaluating psychosis in a pregnant woman.
The clinical presentation of anti-NMDAr encephalitis comprises a viral-like illness that later progresses to a constellation of symptoms including, but not limited to, psychiatric manifestations, seizures, decreased consciousness level, dyskinesias, language defect, and autonomic dysfunction.
Anti-NMDAr is associated with the presence of underlying tumors, namely ovarian teratomas containing nervous tissue.  In a cohort study conducted by Titulaer et al. it was found that 50% of anti-NMDAr female patients had ovarian teratomas.  However, in patients older than 45 years, anti-NMDAr encephalitis is rarely accompanied by tumors, and in those cases, carcinomas are more commonly detected leading to a less favourable outcome. 
Anti-NMDAr encephalitis is also associated with preceding herpes simplex encephalitis. Studies have shown that 20–30% of patients with prior HSV encephalitis who present with a relapse of symptoms not related to HSV relapse do have anti-NMDAr antibodies detected in their CSF. 
Treatment options for anti-NMDAr encephalitis include tumor resection and immunosuppressive therapy. Intravenous methylprednisolone, intravenous immunoglobulin G, and plasma exchange represent the first line treatment options. If no clinical improvement is observed, rituximab and cyclophosphamide are suggested as the second line therapies.
Anti-NMDAr IgG antibodies can cross the placenta and have been reported to be detectable in the serum of babies born to affected mothers during pregnancy. However, it is still unclear whether these autoantibodies have noxious effects on the fetal outcome.
We report the case of an acute psychotic episode during pregnancy due to a rare etiology. In rare cases like ours, when you hear hoofbeats, think zebras, not horses.