House had to lie about Naomi's health because he knew Prather would not approve for the trial if he knew she was pregnant. When House said that she couldn't start for three weeks, Prather was going to turn him down as the cancer would have advanced by then. As such, House agreed to start her in two days even though he knew his planned cesarean section meant she would be ineligible for the trial until she healed. Later, Vogler found out about House's deception and removed Naomi from the trial.