can I bleach my roots at 13 weeks?

Okay so I asked my obgyn  if I could  bleached my hair during pregnancy , and she said yes , that is it safe , but in a ventilated area, and not too often. Cause there has not been a case where bleaching hair is a cause of concern .. but, honestly that didnt help much .. i was hoping she will or aither say yes its safe or no not at all ... please help  i have like an 1 .5 in of dark roots theys look awful and Im not planning to go dark again  and regret it like last time.