Yoselyn Ortega appeared in Manhattan state Supreme Court on Friday. She has pleaded not guilty to murder.
Police say they found Ortega last October in the bathroom of her employer's apartment on the city's Upper West Side. The bodies of 6-year-old Lucia Krim and her 2-year-old brother, Leo, were nearby in a pool of blood.
Ortega was hospitalized with stab wounds that police say were self-inflicted.
The family had just moved to New York from San Francisco's Noe Valley. The children's father worked at Bloomberg and Yahoo.
Her sister has said Ortega loved the children and is a peaceful woman.
Ortega's lawyer is challenging the results of her mental exam.
Her next court date is May 6.
(The Associated Press contributed to this report)