During the early months of pregnancy, the hormone progesterone dominates the body. One of the things progesterone does is relaxing the veins. Additionally, pregnant women have more blood that needs to be pumped around the body. Because of this, many women experience hypotension or low blood pressure during the first and second trimesters of their pregnancies. If you are feeling weak, dizzy, and have a tingling feeling in your extremities, this could be due to low blood pressure. Though sometimes unpleasant, low blood pressure is mostly harmless, especially when you are pregnant and the cause is clear.
High blood pressure can also develop during pregnancy. If your healthcare provider finds out you have hypertension before you reach 20 weeks, it will most likely be assumed that you already had a high blood pressure before you got pregnant. After 20 weeks, high blood pressure will be classified as pregnancy hypertension. Like with lower blood pressure, this is not normally dangerous. But if you do have high blood pressure while you are expecting, your doctor or midwife might want to keep a closer eye on you. It is suddenly spiking blood pressure that is a worry, because it can indicate pre-eclampsia, a dangerous pregnancy condition that can quickly turn into eclampsia which can, amongst other things, lead to seizures. For more information about this, see pre-eclampsia cause found.