Some women suffer from low blood pressure during pregnancy. The blood pressure begins to fall during the beginning of the first trimester and is at its lowest during the middle of the second trimester.

It then begins to normalize and the blood pressure returns to normal after the pregnant woman delivers her baby. Sometimes, it may take a few weeks to normalize after delivery.

What does low blood pressure mean in pregnancy?

The average normal blood pressure range in a healthy individual is between 110/70 and 120/80, although this varies a lot during pregnancy.

How much the blood pressure drops varies. However, in most pregnant women, the systolic blood pressure drops by up to 10 mm of Hg and the diastolic drops by up to 15 mm of Hg. This is quite a common phenomenon and is not dangerous.

This is caused by the expansion of the circulatory volume and the dilation of the blood vessels caused by the hormone progesterone.

The pregnant woman may experience symptoms such as dizziness and faints and other symptoms that anyone with low blood pressure experiences.

However, this drop in blood pressure seen in pregnancy is considered normal and you do not see the symptoms of severe hypotension associated with shock, severe blood loss, or sepsis.

Generally, low blood pressure during pregnancy shouldn’t be a cause for concern unless you experience symptoms. However, too much drop in your blood pressure readings can be a sign of a serious, or even life-threatening condition. A drastic fall in blood pressure can lead to falls, organ damage, or shock.

Low blood pressure may also present as a sign of ectopic pregnancy. This occurs when a fertilized egg gets implanted outside the woman’s uterus such as in the fallopian tube.

Causes of low blood pressure in women during pregnancy

It is not uncommon to see low blood pressure levels in women during pregnancy. There is consensus that the blood volume increases significantly during pregnancy and again due to hormonal changes during pregnancy, the blood vessels dilate.

This blood volume expansion and dilation of the blood vessels can cause the blood pressure to drop. This drop in blood pressure starts somewhere during the beginning of the first trimester and is lowest during the middle of the second trimester.

This is a normal phenomenon and the blood pressure returns to normal once the baby is delivered.

Effects of low blood pressure in pregnancy on the baby

Research on the effects of low blood pressure during pregnancy is limited. While some studies indicate that low blood pressure can cause problems such as stillbirth and a low-weight baby, other research shows that some other factors are to blame for these pregnancy complications.

More research, therefore, needs to be carried out to understand the impact of pregnancy low blood pressure on the baby.

Treatment of low blood pressure in pregnancy

No specific treatment is required for low blood pressure during pregnancy, but you should consult your doctor if you experience symptoms.

Doctors don’t recommend medications during pregnancy unless the symptoms are serious or complications set in. Your blood pressure will mostly stabilize on its own during your third trimester of pregnancy.

However, some home remedies are advised which can help.

  • If you feel dizzy, lie down or sit down.
  • Change of posture should be gradual.
  • Always try to lie down on your left side. This will increase blood flow to the heart and subsequently to the brain. This will eliminate the symptom of dizziness and light-headedness.
  • To encourage blood returning to the heart from the lower extremities, you should wear support stockings. These will compress the veins of the legs and force blood upwards towards the heart.
  • Limit caffeinated drinks. The March of Dimes advises women to limit their caffeine intake to less than 200 milligrams per day, which is about one 12-ounce cup of coffee.
  • Avoid standing up for prolonged periods. This can cause blood pressure to drop.
  • Eat several small meals instead of three large ones. This will prevent postprandial hypotension (low blood pressure). Postprandial hypotension is a condition in which the systolic blood pressure drops by 20 mm Hg in a supine/sitting position within 120 minutes after eating a meal.
  • Avoid strenuous physical activity as it can cause blood pressure to drop.
  • Have 4 to 5 low carbohydrate meals per day. The diet should consist of fruits and vegetables. This post on the diet for low blood pressure gives a detailed overview.

Low blood pressure chart during pregnancy

The following chart will give you an idea of where you stand vis-à-vis your blood pressure readings during pregnancy

Severity level                  Systolic                            Diastolic 

Low BP (mild)                     60 mm Hg                           40 mm Hg
Borderline low BP               90 mm Hg                          60 mm Hg
Extremely low BP               50 mm Hg                           33 mm Hg

To summarize:

Many women have low blood pressure during pregnancy and it is usually normal. You should be concerned if its symptoms cause you problems in which case you should consult your doctor.