Think of your blood pressure as your penis.
If the pressure is too high, you'll walk around with a permanent erection which eventually will become inconvenient. If you don't believe me, try overdosing on Viagra. (After you've spoken with your AME of course.) Too low a blood pressure has, as its analogy in the context, a retracted penis. A retracted penis often causes embarrassment when you try to stand it up. Faced with either of these options, although the former sounds more amusing, it will soon dawn on one that average is the best place in which to find oneself. Six inches is as you like it and 137/71 should hardly merit a second glance at the Sphygmomanometer even were the physician a woman of good repute. As between each state of penile pronouncement a different Texas Condom is required just as a particular treatment is necessary for either high or low blood pressure. All should be avoided whenever possible for these treatments are a life time affliction just like wearing the jolly old snappy latex.
The next time the doctor places the blood pressure arm band around your upper arm, try not to think of the rise and fall of your penis. Failure to do as suggested will almost inevitably lead to you laughing out loud and a subtle change in BP readings.
There are those on this thread who know less than I, some who know more and others who really do. The suspicion is that you'll be told you're quite normally average. One would suggest that you confine your erectile checks to the six months in between each Class 1 medical and don't go messing around and experimenting in areas of science where a little knowledge is a dangerous thing which can lead to paranoia and mental misery. One could get a headache and think one has a brain tumour.