Why monitor your blood pressure during pregnancy?
Blood pressure during pregnancy should be monitored because hypertension can affect the health of the mother and newborn infant. The main purpose of this monitoring is to prevent a complication in pregnancy known as pre-eclampsia. In its most serious form this condition can put the the life of the fetus and the mother at risk.
Is hypertension during pregnancy common?
Hypertension during pregnancy is not exceptional. It is estimated that it occurs in one in ten pregnancies (10% of cases) for first pregnancies, and less frequently (2-5% of cases) for women who have already had children. Most often (two-thirds) hypertension occurs in women who are already hypertensive. Other risk factors for preeclampsia are a first pregnancy (primiparity), twins (twin pregnancies), a personal or family history of preeclampsia, diabetes and obesity.
What is pre-eclampsia?
During pregnancy, the vascular system creates a new balance between the blood circulation of the mother and the fetus: to ensure nourishment of the fetus, the cardiac rate of the mother increases and blood pressure drops (physiological change) from early pregnancy. When this balance is disturbed, blood pressure abnormalities can lead to serious conditions, notably pre-eclampsia (formerly known as toxemia of pregnancy) which includes:
• confirmed blood pressure above 140/90 mmHg,
• protein in the urine (proteinuria) greater than 0.3g / 24h
• and in its severe forms, other abnormalities such as coagulation or liver function disorders.
What are the warning signs for pre-eclampsia? What constitutes an emergency?
Most often, pre-eclampsia is benign, but you should be able to recognize the warning signs that signal you must contact a doctor or midwife immediately. This is the case when:
• blood pressure exceeds 160/110 mm Hg.
• proteinuria exceeds 2 grams per 24 hours, sometimes accompanied by generalized edema (face, hands, lower limbs …).
• severe headaches or disturbances in vision or hearing are experienced
• epigastric pain (located at the epigastrium or right hypochondrium) is experienced
These cases require rapid specialist advice with hospital supervision.
Much more rarely, and asking for necessitating the intervention of mobile emergency services, pre-eclampsia causes:
• convulsions (their presence indicates a very serious condition, the life of the mother is at risk)
• sudden shortness of breath (which may indicate pulmonary edema)
What if I have edema?
The presence of edema (swelling of the legs, feet or hands) is common in the third trimester of pregnancy, so the presence of edema is no longer part of the definition of pre-eclampsia. In cases of edema, it is recommended not to take diuretic drugs and not to follow a salt free diet because they are likely to harm the fetus. The aggravation of oedemas, especially in the area of the face can be a sign of pre-eclampsia.
If my blood pressure rises during pregnancy what different situations can I find myself in?
Increased blood pressure during pregnancy covers widely varied situations of differing gravity and underlying mechanisms. There are four situations that should not be confused:
• 1- a preexisting condition of chronic hypertension
• 2- Added pre-eclampsia; the appearance of marked proteinuria in a previously hypertensive woman
• 3- gestational hypertension. This is unidentified hypertension which is discovered only after 20 weeks of amenorrhea (when menstruation stops).
• 4- pre-eclampsia; it is a specific disease of pregnancy that combines hypertension and proteinuria;
What blood pressure threshold defines hypertension during pregnancy?
Hypertension in pregnancy is defined by the repeated finding of a blood pressure reading above 140/90 mm Hg, when the arterial pressure is measured by the doctor, the nurse or the midwife, during consultations, in a quiet setting, away from any conversation and/or gynecological examination. As the « white coat » effect (blood pressure increased by the stress of a doctor’s presence) is often accentuated in the pregnant woman it is useful to use self-measurement or to record blood pressure readings over a 24hour period (known as MAPA)
What constitutes appropriate monitoring during a pregnancy with hypertension?
During a pregnancy with high blood pressure (present before pregnancy or discovered during it), it is necessary to:
• measure blood pressure regularly
• look for proteinuria regularly
• Perform a blood test to evaluate the impact on the liver and kidneys of hypertension, at regular intervals.
In most cases, no hospitalization is necessary, especially when proteinuria remains below 0.3 grams per day, and the woman does not experience symptoms such as unusual headaches or visual disturbances, pain or edema.
As long as the systolic pressure remains below 150 mm Hg and the diastolic below 110 mm Hg and there is no proteinuria, antihypertensive drugs are not generally given. To avoid unnecessary prescribing, the first recommended line of treatment is rest (stopping work) for hypertensive pregnant women.
Of course women who already have heart disease or kidney disease should be monitored in hospital or receive specific treatments.
I was already hypertensive before my pregnancy, can I continue my treatment during my pregnancy ?
The treatment of hypertension during pregnancy must avoid two opposing errors:
– On the one hand, excessive and inappropriate treatment: even in women who are already receiving an antihypertensive drug before pregnancy, treatment is sometimes reduced, and resumed a little later in pregnancy. An abrupt drop in, or excessively low, blood pressure can affect the fetus while overly intense treatment may be responsible for a low birth weight.
– on the other hand, withholding treatment that would prevent complications.
Previous antihypertensive medications should therefore be adapted early in pregnancy in terms of class and dosage:
– class of drugs: some antihypertensives are contraindicated during pregnancy because known to have consequences for the fetus. In particular, ACE inhibitors and sartans (angiotensin II antagonists) should be avoided. It is even recommended to avoid this type of medication in young hypertensive women who want a child to avoid having to change treatment when the pregnancy occurs. Diuretics are also not recommended for the risk of imbalance they cause the fetus. These medicines should be stopped on the advice of your doctor and if necessary an antihypertensive drug compatible with pregnancy will be prescribed.
– dosage (dosage): when the systolic blood pressure is between 150 and 160 mmHg (and diastolic remains below 110 mmHg) both options (give a drug or not) exist, it depends on the judgment of the doctor according to the person concerned (his antecedents, the presence or not of other diseases, (co-morbidities) the conditions of monitoring etc.).
When is treatment offered during pregnancy in a woman without a previous history of treatment?
Medication is used when the systolic pressure exceeds 160 mmHg and the diastolic is around 100 or 110 mmHg. This threshold exceeded, the blood pressure of the mother will be lowered gently so as not to deregulate that of the fetus.
What antihypertensive drug to avoid during pregnancy?
The choice of medicines to offer to pregnant women is precise: it is imperative to avoid those that are likely to cause malformations in the fetus (scientifically one speaks about « teratogenic risk ») or spontaneous abortions. Among them, inhibitors of the conversion enzyme (IEC) and angiotensin II antagonists are to be avoided. Diuretics are also not recommended for the risk of imbalance they cause the fetus. It would be a mistake to use them, as sometimes happens when the prescriber mistakenly thinks he can correct edema with this type of medicine.
What antihypertensive drug to use during pregnancy?
To treat hypertension during pregnancy, central antihypertensives (methydopa for example), alpha and beta-blockers and calcium channel blockers are primarily used. Follow-up continues after delivery and the treatment is adapted according to the evolution of the tension. In cases of hypertension occurring only during pregnancy, also called gestational hypertension, it is sometimes possible to stop the treatment under monitoring
When will the delivery take place?
As long as the health of the mother and the fetus is not compromised, the pregnancy can be continued until term. Delivery can be done vaginally or by caesarean section, depending on the individual context. In the most serious cases, it may be necessary to decide on early, even premature, delivery. In other words, it may be necessary to terminate the pregnancy and the use of caesarean section is the only way to interrupt the circulatory imbalance that threatens the mother’s vital prognosis.
How to monitor your blood pressure ?
The doctor and / or midwife decides how to monitor blood pressure during pregnancy. Self-measurement is a useful method that allows self-monitoring and early detection of any abnormalities. To learn how to self-measure home blood pressure, please see videos and explanations on www.hy-result.com
February 2019 – Nicolas Postel-Vinay (MD) Guillaume Bobrie (MD) Hypertension unit, Hôpital européen Georges Pompidou-Paris (France)