Believe it or not, low blood pressure is an extremely important adaptation to a healthy pregnancy. The way your body works under ideal circumstances is to make your blood container larger to accommodate more blood. Pregnancy hormones cause your vascular system to enlarge in preparation for increased blood volume which is necessary for a healthy pregnancy but it takes your body three months to produce hemoglobin. This lag in producing the additional hemoglobin to fill the expanded capacity of your body’s blood container lowers your blood pressure. That’s why blood pressure must be lower for pregnancy in order to manage to accommodate the additional blood needed for your baby, placenta, and uterus.
Sometimes very healthy young women will start pregnancy with a blood pressure between 100 over 60 to 65. Their blood pressure may even decrease down to 90 over 50. But as long as you can get up and move around without fainting or falling, your blood pressure is high enough. There are very few natural pregnancy complications that would cause blood pressure to be too low. Anemia could be one cause. Your hemoglobin should be 11, 12, or 13.
Occasionally some emergency room doctors may try to raise a pregnant women’s low blood pressure with IV fluids, not understanding that pregnant women have low blood pressure at times during a pregnancy. Giving IV fluids for normal low blood pressure in pregnant women can have catastrophic outcomes.
The development of low blood pressure during pregnancy sometimes has annoying manifestations, including feeling faint in the shower. Women in the first or early second trimester may feel faint or dizzy when they shower. I think this is a combination of low blood sugar, motion sickness, and low blood pressure. That’s the reason I recommend showering after you eat. You will be less likely to feel faint in the shower.
Sometimes you might feel lightheaded when you stand up. When you stand up, just take some time before you start walking. A word of caution; if you feel dizzy or weak, get out of the shower, or sit down, but DO NOT FALL. As long as you are conscious and you can stand and walk, your pressure is high enough.
In pregnancy low blood pressure can be considered normal unless it is associated with blood loss from, for example, bleeding after a car crash. High blood pressure, on the other hand, is considered harmful because it is associated with difficult pregnancy outcomes such as preeclampsia. Occasionally there are women who do not enlarge their intravascular volume and therefore develop high blood pressure during pregnancy. Without an expanded blood volume, they become intolerant of carrying a pregnancy to term, so may develop preeclampsia.
There are no foods that I know of that will make blood pressure low or high. In pregnancy, you should always have at least three large meals a day and three or four small meals daily. It is best if you eat like a diabetic and that you have a well-rounded diet including about 100 to 120 grams of protein balanced with carbs and fat. This is not the time to try out a low or high carb diet.
It is normal for your blood pressure to be low in pregnancy, especially in the late first trimester and early second trimester. Once your blood volume increases, which should happen in the second trimester, your pressure should go up to your pre-pregnant level. Then you should have less trouble feeling faint.
As long as you can walk and stand, your blood pressure is not too low.