No, hindi naman kailangan ng permission from the OB kasi ang 3D is naman is for aesthetic purposes and hindi naman medical. You can try sa clinic where you’re planning to get the scan done if puwede pa yung 33 weeks although ang sabi ng OB ko hindi na recommended kapag ganyan na ka-late kasi konti nalang daw yung fluid sa loob ng amniotic sack unlike kapag mga late 20 weeks up until around 30 weeks. But it’s still up to you, momsh. 😊