Low Pressure in Pregnancy

Premise

Low blood pressure is a condition in which blood pressure values ​​at rest are lower than normal.

In numerical terms, if the normal arterial pressure falls within a range of values ​​ranging from 90/60 mmHg to 129/84 mmHg, hypotension sufferers have a resting arterial pressure lower than 90/60 mmHg (NB: the first value it is the so-called systolic or maximum pressure, while the second value is the so-called diastolic or minimum pressure ).

NB: low blood pressure is also known by the medical term " hypotension ".

What is low blood pressure during pregnancy?

Low blood pressure in pregnancy is a very common phenomenon, which is strictly dependent on the characteristic hormonal changes of this particular period of a woman's life.

What is the real maker of low blood pressure in pregnancy?

The low blood pressure in pregnancy is determined by peripheral vasodilation, deriving from the natural production of the hormone progesterone and having the task of guaranteeing the fetus the blood supply necessary for its correct development. In essence, therefore, low blood pressure during pregnancy is the result of an absolutely physiological mechanism, without which adequate fetal development could not take place.

To learn more about the functions of progesterone during pregnancy, read: Hormones and pregnancy

Readers are reminded that among the factors affecting blood pressure are also the so-called peripheral resistances, ie the resistances opposed to blood circulation from the state of constriction of small arterial vessels. Faced with a decline in these resistances - a decrease that can occur following a peripheral vasodilation - the arterial pressure decreases.

When does it start and how serious is the phenomenon of low blood pressure during pregnancy?

In pregnant women, blood pressure tends to progressively fall from the earliest weeks of pregnancy.

At the 24th week of gestation, the magnitude of the blood pressure drop is, according to statistical averages, about 5-10 points, for systolic blood pressure, and just over 10 points, for diastolic blood pressure. In essence, therefore, it is almost always a reduction in the arterial pressure of a mild degree .

How long does low blood pressure last during pregnancy?

In pregnant women, low blood pressure is a condition that is generally maintained until the end of the second trimester of pregnancy . After that, in fact, a gradual rise in blood pressure values ​​and their return, near the birth, to pre-pregnancy levels (ie before pregnancy) are realized.

Risk factors for low blood pressure in pregnancy

The drop in blood pressure during pregnancy is already a highly probable phenomenon.

However, there are circumstances that make it even more concrete and that a woman and her gynecologist must consider at the time of a possible gestation.

Among the aforementioned circumstances, the main ones are:

• The presence of a constitutional hypotension, that is the tendency to always have a low pressure of a mild degree;
• The presence of hormonal diseases, such as Addison's disease or diabetes ;
• The presence of cardiac disorders, such as bradycardia or slight arrhythmias ;
• The tendency to suffer from anemia ;
• The low intake of folate and vitamin B12 through the diet.

Consequences

If for chronically hypertensive women low blood pressure in pregnancy can be valuable, for many Normotese women and for most women with symptoms of hypotension even before the happy event, the drop in blood pressure associated with gestation can be a source of problems.

Among these problems, the most common are: weakness, dizziness, dizziness, fainting, blurred vision, nausea, headache and fatigue.

A peculiarity of the symptoms ranging from weakness to blurred vision is that of revealing oneself especially during the passage from the sitting / lying position to the standing position.

Curiosity: during pregnancy what other phenomenon typically accompanies peripheral vasodilation?

In pregnancy, peripheral vasodilation induced by progesterone is associated with increased frequency and cardiac output.

Together, these three events are intended to satisfy fetal blood needs.

What behaviors can aggravate symptoms of low blood pressure during pregnancy?

A series of incorrect behavioral habits can aggravate the symptoms of low blood pressure during pregnancy.

Among these behavioral habits, we note in detail:

• Get up too quickly from a sitting or lying position .

  The sudden passage from the sitting / lying position to the erect one involves, due to the force of gravity, a sudden recall of blood to the lower limbs (therefore to the legs).

  If, as happens in the presence of hypotension, the venous system of the legs is unable to immediately return all the seized blood and thus oppose the blood stagnation at the level of the lower limbs, there is an inevitable reduction in the blood return to the heart and the consequent appearance of weakness, dizziness, blurred vision and sense of fainting.

• Lie down on your back (back) .

  Especially in the last two trimesters of pregnancy, the increase in uterine volume may result in the occlusion of the inferior vena cava and pelvic veins.

  This problem is particularly evident when the pregnant woman assumes or is in a supine position, so that about 1/3 of pregnant women develop a condition known as "supine hypotensive syndrome"; the hypotensive syndrome from a supine position includes a wide range of symptoms - including tachycardia, hypotension, anxiety, feeling of nausea and dizziness - all of which can be traced back to taking the lying up belly position.

• Do not provide the right intake of liquids and / or foods .

  Hypoglycemia and dehydration are two triggers and aggravating the condition of hypotension, as they involve a lowering of the total volume of blood circulating in the body (hypovolemia).

  Readers are reminded that among the circumstances affecting blood pressure is volume, that is the aforementioned total volume of blood circulating in the body.

• Eat too large meals .

  After meals, the arterial pressure undergoes a physiological reduction, thanks to the greater flow of blood to the digestive tract and the lower blood perfusion to the other organs of the body.

  Eating too large meals accentuates the aforementioned reduction, particularly in people prone to low blood pressure, such as pregnant women.

• Take alcoholic beverages .

  Besides having deleterious effects on the psycho-physical development of the fetus, alcohol contributes to aggravate the hypotension and the disorders deriving from it, due to its known vasodilator effect.

• Keep the erect position for a long time, especially if static .

  The static maintenance of the standing position for long periods of time involves, due to gravity, the stagnation of blood in the lower limbs. All this, in a person suffering from low blood pressure, has the effect of aggravating the symptoms of hypotension, as there is no adequate blood return to the heart.

Other circumstances that can aggravate low blood pressure during pregnancy

In addition to the behaviors described above, to further aggravate low blood pressure in pregnancy can contribute:

• The presence of iron deficiency anemia, ie the pathological decrease of hemoglobin in the blood (anemia) due to an iron deficiency (iron deficiency).

  In addition to being already a fairly common condition in the female population, iron deficiency anemia is an even more concrete possibility for pregnant women, as pregnancy leads to an increase in iron requirements.

• The high temperature .

  Heat promotes peripheral vasodilation and the sequestration of blood in the lower limbs, two factors which, as we have seen in other circumstances, contribute to the drop in blood pressure, especially in people already prone to the problem (eg: pregnant women).

Complications

If the drop in blood pressure during pregnancy is of a higher than mild degree - a very rare situation indeed - the risk of damage to key organs increases significantly in the expectant mother.

Furthermore, scientific studies have shown that, in such situations, there is also a greater inclination to ectopic pregnancy .

Is low blood pressure in pregnancy harmful to the fetus?

So far, no doctor, researcher, etc. has conducted adequate research on the precise effects on the fetus of low blood pressure during pregnancy.

In the past, however, some experts had advanced the hypothesis, never demonstrated satisfactorily, that the drop in blood pressure of the pregnant woman could lead to the future unborn child: a greater risk of low birth weight, learning difficulties and even death fetal.

When should I see a doctor immediately?

The low pressure during pregnancy obliges the pregnant woman concerned to contact the treating doctor immediately or to go to the nearest hospital, when it causes:

• Repeated faults;
• Strong headaches;
• Prolonged vomiting;
• Dyspnoea;
• Extremely rapid pulse;
• Chest pain;
• Numbness in some part of the body.

Remedies

In most cases, low blood pressure during pregnancy does not require specific treatments and treatments (so no drugs), but requires only a few precautions, useful for controlling the symptomatology of hypotension and preventing it from excessively disturbing the pregnant woman's quality of life.

The measures in question include countermeasures to behavioral habits and circumstances described in the previous chapter, and other remedies.

In detail, here is what these countermeasures and remedies consist of:

• Switch from a sitting / lying position to a standing position gradually, rather than suddenly;
• Lie on your left side instead of your back. In this way, blood flow to the heart is encouraged even in a lying position. To make the position more comfortable, you can place a pillow under your thighs or along your back.

  It is particularly important to follow this countermeasure starting from the 16th week of gestation;

• Eat small, frequent meals and take generous amounts of liquids ;
• Avoid the consumption of alcoholic beverages ;
• When the upright position is maintained for long periods of time, stimulate blood circulation along the lower limbs, through periodic movement of the leg muscles . It is useful, for example, to get up from time to time on the toes, as this movement involves an alternation of contractions and relaxations which acts as a "pump effect" against the blood;
• Avoid staying in excessively hot and humid environments ;
• Integrate the intake of iron from the diet through specific supplements, as prescribed by the doctor;
• Avoid coffee consumption, especially in the evening or at bedtime. Coffee has hypotensive effects;
• Avoid intense physical activity . After carrying out vigorous physical activity, blood pressure tends to fall;
• Wear compression stockings . This type of stockings favors the return of venous blood from the lower limbs to the heart and is an excellent remedy against low blood pressure during pregnancy and beyond.

Curiosity: how to prepare for low blood pressure during pregnancy

A pregnant woman can reduce the impact with low blood pressure by using some strategies, including: providing adequate hydration, sticking to a balanced diet, taking vitamin and folate supplements and adding a pinch of extra salt into the diet.