low diastolic blood pressure

Hey. I'm about 20 weeks pregnant. I have "white coat syndrome" anyothet words I get anxious subconsciously at doctors and my BP elevates, been this way for years. Doctors not concerned. I have a BP arm cuff at home for my own peace of mind and check a few times a week. My BP usually runs low normal but lately my bottom number has been in the 50s. Wonder why? Because I get anxious at docs it wouldn't show that low In their office