Blood Pressure in Pregnancy
The blood pressure normally falls during pregnancy. Rising of blood pressure during pregnancy indicates the risk of pre-eclampsia or eclampsia. That’s the reason doctors and nurses keep measuring the blood pressure during pregnancy.
Normally, pregnancy lasts for 38-42 weeks, in which there are three different stages of development. These three stages are called trimesters. The first trimester is the first 13 weeks of pregnancy, roughly calculated from the time the fetus starts forming. The second trimester starts from 14-27 weeks of pregnancy and the third trimester starts from 28 weeks of pregnancy until birth.
Change of blood pressure in pregnancy:
Normally the blood pressure falls during the second trimester of pregnancy. Then, it generally rises slowly until birth, although the level may still be lower than the level before pregnancy. After birth, the level will slowly increase and regain its usual level.
Why does blood pressure fall in pregnancy?
When a person gets pregnant, she needs more oxygen to develop the baby. Therefore, the body starts making more blood to receive enough oxygen for both the mother and the baby. This increases the total volume of the blood rapidly during the first 11-13 weeks of pregnancy, which causes a rise in blood pressure.
To prevent the rise in blood pressure, the placenta that nourishes the baby in the womb starts releasing hormones. These hormones help make the walls of small arteries and veins more elastic and make room for the increased blood volume without rise in blood pressure. And because of this, the heart doesn’t have to pump very hard, which makes your blood pressure fall during pregnancy.
High blood pressure during pregnancy:
A blood pressure of more than 40/90 mmhg is conventionally considered as high during pregnancy. Again, the effect of this level will depend on whether you had high blood pressure before you got pregnant or whether it increased after you became pregnant.