Blood pressure can be explained as the force of blood created when it is pushed against the walls of the artery as our heart performs its pumping action. This pressure fluctuates as we feel excited or nervous and it is normal for the pressure to go up and down several times in a day. The readings of blood pressure can reveal important information about our health. Experiencing low blood pressure during pregnancy is quite common especially in mid second trimester and third trimester. However, pregnancy’s effect on blood pressure starts occurring from the first trimester.
When pregnant, the blood pressure reading tells us about the health of both the expecting mother and the baby. It also helps the doctor in determining the presence of a number of other health conditions such as preeclampsia. This is why at every prenatal visit, your gynecologist or doctor will check your blood pressure so as to ensure that it is in its normal ranges. Let’s find out more about why women experience low blood pressure during pregnancy, what are its symptoms, and treatment options. 
What is Low Blood Pressure?
According to current guidelines, reading under 120 mm Hg systolic and over 80 mm Hg diastolic would be normal and if the reading is lower than 90/60 mm Hg then it would be considered low.
Causes of Low Blood Pressure During Pregnancy
Low blood pressure during pregnancy is caused by the changes that happen in a woman’s body while carrying a baby. This is so because pregnancy causes the circulatory system to expand quickly and the blood vessels dilate leading to a drop in the blood pressure. Actually, the rapid expansion in blood volume, which occurs for maintaining sufficient supply of oxygen and nutrients to the baby, dilates the blood vessels and leads to hypotension in pregnancy. 
In fact, low blood pressure is the third most common cause of hypotension among pregnant women while other issues that may cause low BP include the presence of twins/triplets/quadruplets, deficiency of folic acid or vitamin B12. At the time of delivery if an epidural is administered then sudden drop in blood pressure will be recorded.
In the first 24 weeks of pregnancy, it is expected that the blood pressure will drop and it will be at its lowest levels in the middle of the second trimester. 
There are various other reasons that lead to low blood pressure such as conditions like anemia, infections, endocrine disorders, heart-related issues, internal bleeding, dehydration, allergic reaction to something, prolonged bed rest, and nutritional deficiencies. A decrease in blood volume also drops blood pressure, such as if dehydration is severe or a lot of blood has been lost due to internal bleeding.
Furthermore, various over the counter drugs also cause low BP including diuretics that treat hypertension, antidepressants, and other prescription drugs. Alcohol and narcotics’ use also lowers blood pressure in pregnant ladies. 
Symptoms of Low Blood Pressure During Pregnancy
Very often, low blood pressure is an indication of another underlying health issue especially when the drop is sudden and it is followed by other symptoms like dizziness, lightheadedness, syncope (fatigue), nausea, blurred vision, depression, shock, difficulty in concentrating, and lethargy. If the condition persists, the expecting mother will notice other symptoms such as shallow breathing and rapid or weak pulse. 
On the other hand, low blood pressure may not always indicate a problem for the mother-to-be and just be caused by the hormonal changes that occur in the body during pregnancy.
Risks in 3rd Trimester
Low blood pressure during first and second trimester is not a cause of concern for the doctor but during the third trimester, it does become alarming. Especially if the drop is significantly high then this could be life-threatening for the growing baby as well as the mother. Very low blood pressure leads to organ damage, fainting, and shock. Very low blood pressure could be a sign of ectopic pregnancy as well, in which the egg is fertilized but gets implanted outside of the uterus and inside the fallopian tube.
It is believed that low blood pressure during pregnancy is linked with poor perinatal outcomes. However, a study published in the American Journal of Epidemiology using data from the Collaborative Perinatal Project revealed that low blood pressure and poor perinatal outcomes are not directly linked because the latter is caused majorly by other risk factors. Therefore, it is an incorrect notion that low blood pressure increases the risk of poor perinatal outcomes.
Effects on the Baby
As per some studies, low blood pressure during pregnancy can lead to issues like low birth weight and may even cause stillbirth. This can occur if the mother experiences low blood pressure continually during the third trimester. A considerable amount of research has been done on the impact of high blood pressure on the baby, but not much research is conducted on the effect of low blood pressure.
Usually, low BP during pregnancy is not treated with medication but through foods and lifestyle changes. In a majority of the cases, blood pressure begins to increase and remains elevated during the third trimester and becomes completely normal after childbirth. Expecting mothers can also try the following remedies for treating low BP issue:
- Choosing to lie on their left side to regulate and increase blood flow
- Avoiding rapid movements
- Avoiding standing for long duration because it causes miscommunication between brain and heart
- Lying down or sitting still after having a meal
- Avoiding lying on the back, especially after the fifth month of pregnancy because this leads to adding pressure on the uterus, which presses principal blood vessels and results in decreasing blood flow
- Never do strenuous exercises when pregnant
- Your GP may also change your medication if it is believed that a certain medicine is causing a decrease in blood pressure.
What to Eat?
Pregnant ladies need to consume fresh fruits, vegetables, dark green leafy vegetables, lean meat, and complex carbohydrates. Basically, maintaining a healthy and balanced diet is the key. Avoiding alcohol and tobacco also work wonders on our body while whole grain cereals, oatmeal, low-fat milk, and curd are very beneficial. Doctors advise expecting mothers to take small but frequent meals throughout the day, but the meals should be low carbohydrates. Low BP patients also need to avoid spicy, oily, and fried stuff as well as processed foods.