I Am 39 Weeks Pregnant And My Blood Pressure Is 140 Over 90, Is This A Dangerous Reading?

There are 3 possibilities about your blood pressure.  

1. Are you having this blood pressure before pregnancy or before 20 weeks of pregnancy?
   
2. Are you having this blood pressure since last few days or weeks?
3. Did you develop this blood pressure after 20 weeks of pregnancy.

Condition number 1 can affect your baby's health. Condition number two can not harm your baby but in future can harm you. Condition number three is not good both for you and your baby. So, you should get advice from your doctor.